Listen for wifi AP state changes.

We won't necessarily receive a connectivity change event when the wifi AP is enabled.

.idea/runConfigurations/H2_Performance_Test.xml

@@ -0,0 +1,23 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="H2 Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
+    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
+    <module name="bramble-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
+    <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
+    <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.H2DatabasePerformanceTest" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="class" />
+    <option name="VM_PARAMETERS" value="-ea" />
+    <option name="PARAMETERS" value="" />
+    <option name="WORKING_DIRECTORY" value="" />
+    <option name="ENV_VARIABLES" />
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <envs />
+    <patterns />
+    <method />
+  </configuration>
+</component>

.idea/runConfigurations/HyperSQL_Performance_Test.xml

@@ -0,0 +1,23 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="HyperSQL Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
+    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
+    <module name="bramble-core" />
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
+    <option name="ALTERNATIVE_JRE_PATH" />
+    <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
+    <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.HyperSqlDatabasePerformanceTest" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="class" />
+    <option name="VM_PARAMETERS" value="-ea" />
+    <option name="PARAMETERS" value="" />
+    <option name="WORKING_DIRECTORY" value="" />
+    <option name="ENV_VARIABLES" />
+    <option name="PASS_PARENT_ENVS" value="true" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="singleModule" />
+    </option>
+    <envs />
+    <patterns />
+    <method />
+  </configuration>
+</component>

bramble-android/build.gradle

@@ -12,8 +12,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 1621
-		versionName "0.16.21"
+		versionCode 1700
+		versionName "0.17.0"
 		consumerProguardFiles 'proguard-rules.txt'
 	}
 
@@ -43,6 +43,7 @@ dependencyVerification {
 			'com.madgag.spongycastle:core:1.58.0.0:core-1.58.0.0.jar:199617dd5698c5a9312b898c0a4cec7ce9dd8649d07f65d91629f58229d72728',
 			'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
 			'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
+			'net.i2p.crypto:eddsa:0.2.0:eddsa-0.2.0.jar:a7cb1b85c16e2f0730b9204106929a1d9aaae1df728adc7041a8b8b605692140',
 			'org.bitlet:weupnp:0.1.4:weupnp-0.1.4.jar:88df7e6504929d00bdb832863761385c68ab92af945b04f0770b126270a444fb',
 			'org.jacoco:org.jacoco.agent:0.7.4.201502262128:org.jacoco.agent-0.7.4.201502262128-runtime.jar:e357a0f1d573c2f702a273992b1b6cb661734f66311854efb3778a888515c5b5',
 			'org.jacoco:org.jacoco.agent:0.7.4.201502262128:org.jacoco.agent-0.7.4.201502262128.jar:47b4bec6df11a1118da3953da8b9fa1e7079d6fec857faa1a3cf912e53a6fd4e',

bramble-android/proguard-rules.txt

@@ -8,6 +8,10 @@
 -dontwarn dagger.**
 -dontnote dagger.**
 
+-keep class net.i2p.crypto.eddsa.** { *; }
+
+-keep class org.whispersystems.curve25519.** { *; }
+
 -dontwarn sun.misc.Unsafe
 -dontnote com.google.common.**
 

bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java

@@ -48,7 +48,7 @@ public class AndroidPluginModule {
 				appContext, locationUtils, reporter, eventBus,
 				torSocketFactory, backoffFactory);
 		DuplexPluginFactory lan = new AndroidLanTcpPluginFactory(ioExecutor,
-				scheduler, backoffFactory, appContext);
+				backoffFactory, appContext);
 		Collection<DuplexPluginFactory> duplex =
 				Arrays.asList(bluetooth, tor, lan);
 		@NotNullByDefault

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -5,84 +5,43 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
-import android.net.Network;
 import android.net.NetworkInfo;
-import android.net.wifi.WifiInfo;
-import android.net.wifi.WifiManager;
+import android.os.Bundle;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 
-import java.io.IOException;
-import java.net.InetAddress;
-import java.net.Socket;
-import java.net.UnknownHostException;
-import java.util.Collection;
 import java.util.concurrent.Executor;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.net.SocketFactory;
 
 import static android.content.Context.CONNECTIVITY_SERVICE;
-import static android.content.Context.WIFI_SERVICE;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.net.wifi.WifiManager.EXTRA_WIFI_STATE;
-import static android.os.Build.VERSION.SDK_INT;
-import static java.util.Collections.emptyList;
-import static java.util.Collections.singletonList;
-import static java.util.concurrent.TimeUnit.SECONDS;
+import static java.util.logging.Level.INFO;
+import static org.briarproject.bramble.util.AndroidUtils.logNetworkState;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin {
 
-	// See android.net.wifi.WifiManager
-	private static final String WIFI_AP_STATE_CHANGED_ACTION =
+	private static final String WIFI_AP_STATE_ACTION =
 			"android.net.wifi.WIFI_AP_STATE_CHANGED";
-	private static final int WIFI_AP_STATE_ENABLED = 13;
-
-	private static final byte[] WIFI_AP_ADDRESS_BYTES =
-			{(byte) 192, (byte) 168, 43, 1};
-	private static final InetAddress WIFI_AP_ADDRESS;
-
 	private static final Logger LOG =
 			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
 
-	static {
-		try {
-			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
-		} catch (UnknownHostException e) {
-			// Should only be thrown if the address has an illegal length
-			throw new AssertionError(e);
-		}
-	}
-
-	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
-	private final ConnectivityManager connectivityManager;
-	@Nullable
-	private final WifiManager wifiManager;
 
 	@Nullable
 	private volatile BroadcastReceiver networkStateReceiver = null;
-	private volatile SocketFactory socketFactory;
 
-	AndroidLanTcpPlugin(Executor ioExecutor, ScheduledExecutorService scheduler,
-			Backoff backoff, Context appContext, DuplexPluginCallback callback,
-			int maxLatency, int maxIdleTime) {
+	AndroidLanTcpPlugin(Executor ioExecutor, Backoff backoff,
+			Context appContext, DuplexPluginCallback callback, int maxLatency,
+			int maxIdleTime) {
 		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
-		this.scheduler = scheduler;
 		this.appContext = appContext;
-		ConnectivityManager connectivityManager = (ConnectivityManager)
-				appContext.getSystemService(CONNECTIVITY_SERVICE);
-		if (connectivityManager == null) throw new AssertionError();
-		this.connectivityManager = connectivityManager;
-		wifiManager = (WifiManager) appContext.getApplicationContext()
-				.getSystemService(WIFI_SERVICE);
-		socketFactory = SocketFactory.getDefault();
 	}
 
 	@Override
@@ -93,8 +52,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		networkStateReceiver = new NetworkStateReceiver();
 		IntentFilter filter = new IntentFilter();
 		filter.addAction(CONNECTIVITY_ACTION);
-		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
+		filter.addAction(WIFI_AP_STATE_ACTION);
 		appContext.registerReceiver(networkStateReceiver, filter);
+		if (LOG.isLoggable(INFO)) logNetworkState(appContext, LOG);
 	}
 
 	@Override
@@ -105,92 +65,38 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		tryToClose(socket);
 	}
 
-	@Override
-	protected Socket createSocket() throws IOException {
-		return socketFactory.createSocket();
-	}
-
-	@Override
-	protected Collection<InetAddress> getLocalIpAddresses() {
-		// If the device doesn't have wifi, don't open any sockets
-		if (wifiManager == null) return emptyList();
-		// If we're connected to a wifi network, use that network
-		WifiInfo info = wifiManager.getConnectionInfo();
-		if (info != null && info.getIpAddress() != 0)
-			return singletonList(intToInetAddress(info.getIpAddress()));
-		// If we're running an access point, return its address
-		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
-				return singletonList(WIFI_AP_ADDRESS);
-		// No suitable addresses
-		return emptyList();
-	}
-
-	private InetAddress intToInetAddress(int ip) {
-		byte[] ipBytes = new byte[4];
-		ipBytes[0] = (byte) (ip & 0xFF);
-		ipBytes[1] = (byte) ((ip >> 8) & 0xFF);
-		ipBytes[2] = (byte) ((ip >> 16) & 0xFF);
-		ipBytes[3] = (byte) ((ip >> 24) & 0xFF);
-		try {
-			return InetAddress.getByAddress(ipBytes);
-		} catch (UnknownHostException e) {
-			// Should only be thrown if address has illegal length
-			throw new AssertionError(e);
-		}
-	}
-
-	// On API 21 and later, a socket that is not created with the wifi
-	// network's socket factory may try to connect via another network
-	private SocketFactory getSocketFactory() {
-		if (SDK_INT < 21) return SocketFactory.getDefault();
-		for (Network net : connectivityManager.getAllNetworks()) {
-			NetworkInfo info = connectivityManager.getNetworkInfo(net);
-			if (info != null && info.getType() == TYPE_WIFI)
-				return net.getSocketFactory();
-		}
-		LOG.warning("Could not find suitable socket factory");
-		return SocketFactory.getDefault();
-	}
-
 	private class NetworkStateReceiver extends BroadcastReceiver {
 
 		@Override
 		public void onReceive(Context ctx, Intent i) {
 			if (!running) return;
-			if (isApEnabledEvent(i)) {
-				// The state change may be broadcast before the AP address is
-				// visible, so delay handling the event
-				scheduler.schedule(this::handleConnectivityChange, 1, SECONDS);
-			} else {
-				handleConnectivityChange();
+			if (LOG.isLoggable(INFO)) {
+				if (CONNECTIVITY_ACTION.equals(i.getAction())) {
+					LOG.info("Connectivity change");
+					Bundle extras = i.getExtras();
+					if (extras != null) {
+						LOG.info("Extras:");
+						for (String key : extras.keySet())
+							LOG.info("\t" + key + ": " + extras.get(key));
+					}
+				} else if (WIFI_AP_STATE_ACTION.equals(i.getAction())) {
+					int state = i.getIntExtra(EXTRA_WIFI_STATE, 0);
+					if (state == 13) LOG.info("Wifi AP enabled");
+					else LOG.info("Wifi AP state " + state);
+				}
+				logNetworkState(appContext, LOG);
 			}
-		}
-
-		private void handleConnectivityChange() {
-			if (!running) return;
-			Collection<InetAddress> addrs = getLocalIpAddresses();
-			if (addrs.contains(WIFI_AP_ADDRESS)) {
-				LOG.info("Providing wifi hotspot");
-				// There's no corresponding Network object and thus no way
-				// to get a suitable socket factory, so we won't be able to
-				// make outgoing connections on API 21+ if another network
-				// has internet access
-				socketFactory = SocketFactory.getDefault();
+			Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
+			ConnectivityManager cm = (ConnectivityManager) o;
+			NetworkInfo net = cm.getActiveNetworkInfo();
+			if (net != null && net.getType() == TYPE_WIFI
+					&& net.isConnected()) {
+				LOG.info("Connected to Wi-Fi");
 				if (socket == null || socket.isClosed()) bind();
-			} else if (addrs.isEmpty()) {
-				LOG.info("Not connected to wifi");
-				socketFactory = SocketFactory.getDefault();
+			} else {
+				LOG.info("Not connected to Wi-Fi");
 				tryToClose(socket);
-			} else {
-				LOG.info("Connected to wifi");
-				socketFactory = getSocketFactory();
-				if (socket == null || socket.isClosed()) bind();
 			}
 		}
-
-		private boolean isApEnabledEvent(Intent i) {
-			return WIFI_AP_STATE_CHANGED_ACTION.equals(i.getAction()) &&
-					i.getIntExtra(EXTRA_WIFI_STATE, 0) == WIFI_AP_STATE_ENABLED;
-		}
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java

@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
-import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -28,15 +27,12 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
-	private final ScheduledExecutorService scheduler;
 	private final BackoffFactory backoffFactory;
 	private final Context appContext;
 
 	public AndroidLanTcpPluginFactory(Executor ioExecutor,
-			ScheduledExecutorService scheduler, BackoffFactory backoffFactory,
-			Context appContext) {
+			BackoffFactory backoffFactory, Context appContext) {
 		this.ioExecutor = ioExecutor;
-		this.scheduler = scheduler;
 		this.backoffFactory = backoffFactory;
 		this.appContext = appContext;
 	}
@@ -55,7 +51,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new AndroidLanTcpPlugin(ioExecutor, scheduler, backoff,
-				appContext, callback, MAX_LATENCY, MAX_IDLE_TIME);
+		return new AndroidLanTcpPlugin(ioExecutor, backoff, appContext,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -16,7 +16,6 @@ import android.os.PowerManager;
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
-import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -64,6 +63,8 @@ import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
@@ -110,7 +111,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(TorPlugin.class.getName());
 
-	private final Executor ioExecutor, connectionStatusExecutor;
+	private final Executor ioExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final LocationUtils locationUtils;
@@ -124,6 +125,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final File torDirectory, torFile, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final PowerManager.WakeLock wakeLock;
+	private final Lock connectionStatusLock;
 	private final AtomicReference<Future<?>> connectivityCheck =
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -165,9 +167,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		// This tag will prevent Huawei's powermanager from killing us.
 		wakeLock = pm.newWakeLock(PARTIAL_WAKE_LOCK, "LocationManagerService");
 		wakeLock.setReferenceCounted(false);
-		// Don't execute more than one connection status check at a time
-		connectionStatusExecutor = new PoliteExecutor("TorPlugin",
-				ioExecutor, 1);
+		connectionStatusLock = new ReentrantLock();
 	}
 
 	@Override
@@ -697,46 +697,55 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void updateConnectionStatus() {
-		connectionStatusExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			if (!running) return;
-			Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
-			ConnectivityManager cm = (ConnectivityManager) o;
-			NetworkInfo net = cm.getActiveNetworkInfo();
-			boolean online = net != null && net.isConnected();
-			boolean wifi = online && net.getType() == TYPE_WIFI;
-			String country = locationUtils.getCurrentCountry();
-			boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(
-					country);
-			Settings s = callback.getSettings();
-			int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
-
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Online: " + online + ", wifi: " + wifi);
-				if ("".equals(country)) LOG.info("Country code unknown");
-				else LOG.info("Country code: " + country);
-			}
-
 			try {
-				if (!online) {
-					LOG.info("Disabling network, device is offline");
-					enableNetwork(false);
-				} else if (blocked) {
-					LOG.info("Disabling network, country is blocked");
-					enableNetwork(false);
-				} else if (network == PREF_TOR_NETWORK_NEVER
-						|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
-					LOG.info("Disabling network due to data setting");
-					enableNetwork(false);
-				} else {
-					LOG.info("Enabling network");
-					enableNetwork(true);
-				}
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+				connectionStatusLock.lock();
+				updateConnectionStatusLocked();
+			} finally {
+				connectionStatusLock.unlock();
 			}
 		});
 	}
 
+	// Locking: connectionStatusLock
+	private void updateConnectionStatusLocked() {
+		Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
+		ConnectivityManager cm = (ConnectivityManager) o;
+		NetworkInfo net = cm.getActiveNetworkInfo();
+		boolean online = net != null && net.isConnected();
+		boolean wifi = online && net.getType() == TYPE_WIFI;
+		String country = locationUtils.getCurrentCountry();
+		boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(country);
+		Settings s = callback.getSettings();
+		int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
+
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Online: " + online + ", wifi: " + wifi);
+			if ("".equals(country)) LOG.info("Country code unknown");
+			else LOG.info("Country code: " + country);
+		}
+
+		try {
+			if (!online) {
+				LOG.info("Disabling network, device is offline");
+				enableNetwork(false);
+			} else if (blocked) {
+				LOG.info("Disabling network, country is blocked");
+				enableNetwork(false);
+			} else if (network == PREF_TOR_NETWORK_NEVER
+					|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
+				LOG.info("Disabling network due to data setting");
+				enableNetwork(false);
+			} else {
+				LOG.info("Enabling network");
+				enableNetwork(true);
+			}
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
 	private void scheduleConnectionStatusUpdate() {
 		Future<?> newConnectivityCheck =
 				scheduler.schedule(this::updateConnectionStatus, 1, MINUTES);
@@ -778,7 +787,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 		private synchronized void enableNetwork(boolean enable) {
 			networkEnabled = enable;
-			if (!enable) circuitBuilt = false;
+			circuitBuilt = false;
 		}
 
 		private synchronized boolean isConnected() {

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -1,18 +1,41 @@
 package org.briarproject.bramble.util;
 
+import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.Network;
+import android.net.NetworkInfo;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.provider.Settings;
 
 import java.io.File;
+import java.net.InetAddress;
+import java.net.InterfaceAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
+import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
+
+import static android.content.Context.CONNECTIVITY_SERVICE;
 import static android.content.Context.MODE_PRIVATE;
+import static android.content.Context.WIFI_SERVICE;
+import static android.os.Build.VERSION.SDK_INT;
+import static java.net.NetworkInterface.getNetworkInterfaces;
+import static java.util.Collections.list;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.StringUtils.ipToString;
+import static org.briarproject.bramble.util.StringUtils.toHexString;
 
+@SuppressLint("HardwareIds")
 public class AndroidUtils {
 
 	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
@@ -23,7 +46,7 @@ public class AndroidUtils {
 	@SuppressWarnings("deprecation")
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
-		if (Build.VERSION.SDK_INT >= 21) {
+		if (SDK_INT >= 21) {
 			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);
@@ -67,4 +90,123 @@ public class AndroidUtils {
 	public static File getReportDir(Context ctx) {
 		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
 	}
+
+	public static void logNetworkState(Context ctx, Logger logger) {
+		if (!logger.isLoggable(INFO)) return;
+
+		Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
+		if (o == null) throw new AssertionError();
+		ConnectivityManager cm = (ConnectivityManager) o;
+		o = ctx.getApplicationContext().getSystemService(WIFI_SERVICE);
+		if (o == null) throw new AssertionError();
+		WifiManager wm = (WifiManager) o;
+
+		StringBuilder s = new StringBuilder();
+		logWifiInfo(s, wm.getConnectionInfo());
+		logNetworkInfo(s, cm.getActiveNetworkInfo(), true);
+		if (SDK_INT >= 21) {
+			for (Network network : cm.getAllNetworks())
+				logNetworkInfo(s, cm.getNetworkInfo(network), false);
+		} else {
+			for (NetworkInfo info : cm.getAllNetworkInfo())
+				logNetworkInfo(s, info, false);
+		}
+		try {
+			for (NetworkInterface iface : list(getNetworkInterfaces()))
+				logNetworkInterface(s, iface);
+		} catch (SocketException e) {
+			logger.log(WARNING, e.toString(), e);
+		}
+		logger.log(INFO, s.toString());
+	}
+
+	private static void logWifiInfo(StringBuilder s, @Nullable WifiInfo info) {
+		if (info == null) {
+			s.append("Wifi info: null\n");
+			return;
+		}
+		s.append("Wifi info:\n");
+		s.append("\tSSID: ").append(info.getSSID()).append("\n");
+		s.append("\tBSSID: ").append(info.getBSSID()).append("\n");
+		s.append("\tMAC address: ").append(info.getMacAddress()).append("\n");
+		s.append("\tIP address: ")
+				.append(ipToString(info.getIpAddress())).append("\n");
+		s.append("\tSupplicant state: ")
+				.append(info.getSupplicantState()).append("\n");
+		s.append("\tNetwork ID: ").append(info.getNetworkId()).append("\n");
+		s.append("\tLink speed: ").append(info.getLinkSpeed()).append("\n");
+		s.append("\tRSSI: ").append(info.getRssi()).append("\n");
+		if (info.getHiddenSSID()) s.append("\tHidden SSID\n");
+		if (SDK_INT >= 21)
+			s.append("\tFrequency: ").append(info.getFrequency()).append("\n");
+	}
+
+	private static void logNetworkInfo(StringBuilder s,
+			@Nullable NetworkInfo info, boolean active) {
+		if (info == null) {
+			if (active) s.append("Active network info: null\n");
+			else s.append("Network info: null\n");
+			return;
+		}
+		if (active) s.append("Active network info:\n");
+		else s.append("Network info:\n");
+		s.append("\tType: ").append(info.getTypeName())
+				.append(" (").append(info.getType()).append(")\n");
+		s.append("\tSubtype: ").append(info.getSubtypeName())
+				.append(" (").append(info.getSubtype()).append(")\n");
+		s.append("\tState: ").append(info.getState()).append("\n");
+		s.append("\tDetailed state: ")
+				.append(info.getDetailedState()).append("\n");
+		s.append("\tReason: ").append(info.getReason()).append("\n");
+		s.append("\tExtra info: ").append(info.getExtraInfo()).append("\n");
+		if (info.isAvailable()) s.append("\tAvailable\n");
+		if (info.isConnected()) s.append("\tConnected\n");
+		if (info.isConnectedOrConnecting())
+			s.append("\tConnected or connecting\n");
+		if (info.isFailover()) s.append("\tFailover\n");
+		if (info.isRoaming()) s.append("\tRoaming\n");
+	}
+
+	private static void logNetworkInterface(StringBuilder s,
+			NetworkInterface iface) throws SocketException {
+		s.append("Network interface:\n");
+		s.append("\tName: ").append(iface.getName()).append("\n");
+		s.append("\tDisplay name: ")
+				.append(iface.getDisplayName()).append("\n");
+		s.append("\tHardware address: ")
+				.append(hexOrNull(iface.getHardwareAddress())).append("\n");
+		if (iface.isLoopback()) s.append("\tLoopback\n");
+		if (iface.isPointToPoint()) s.append("\tPoint-to-point\n");
+		if (iface.isVirtual()) s.append("\tVirtual\n");
+		if (iface.isUp()) s.append("\tUp\n");
+		if (SDK_INT >= 19)
+			s.append("\tIndex: ").append(iface.getIndex()).append("\n");
+		for (InterfaceAddress addr : iface.getInterfaceAddresses()) {
+			s.append("\tInterface address:\n");
+			logInetAddress(s, addr.getAddress());
+			s.append("\t\tPrefix length: ")
+					.append(addr.getNetworkPrefixLength()).append("\n");
+		}
+	}
+
+	private static void logInetAddress(StringBuilder s, InetAddress addr) {
+		s.append("\t\tAddress: ")
+				.append(hexOrNull(addr.getAddress())).append("\n");
+		s.append("\t\tHost address: ")
+				.append(addr.getHostAddress()).append("\n");
+		if (addr.isLoopbackAddress()) s.append("\t\tLoopback\n");
+		if (addr.isLinkLocalAddress()) s.append("\t\tLink-local\n");
+		if (addr.isSiteLocalAddress()) s.append("\t\tSite-local\n");
+		if (addr.isAnyLocalAddress()) s.append("\t\tAny local (wildcard)\n");
+		if (addr.isMCNodeLocal()) s.append("\t\tMulticast node-local\n");
+		if (addr.isMCLinkLocal()) s.append("\t\tMulticast link-local\n");
+		if (addr.isMCSiteLocal()) s.append("\t\tMulticast site-local\n");
+		if (addr.isMCOrgLocal()) s.append("\t\tMulticast org-local\n");
+		if (addr.isMCGlobal()) s.append("\t\tMulticast global\n");
+	}
+
+	@Nullable
+	private static String hexOrNull(@Nullable byte[] b) {
+		return b == null ? null : toHexString(b);
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/Multiset.java

@@ -0,0 +1,101 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
+import javax.annotation.concurrent.NotThreadSafe;
+
+@NotThreadSafe
+@NotNullByDefault
+public class Multiset<T> {
+
+	private final Map<T, Integer> map = new HashMap<>();
+
+	private int total = 0;
+
+	/**
+	 * Returns how many items the multiset contains in total.
+	 */
+	public int getTotal() {
+		return total;
+	}
+
+	/**
+	 * Returns how many unique items the multiset contains.
+	 */
+	public int getUnique() {
+		return map.size();
+	}
+
+	/**
+	 * Returns how many of the given item the multiset contains.
+	 */
+	public int getCount(T t) {
+		Integer count = map.get(t);
+		return count == null ? 0 : count;
+	}
+
+	/**
+	 * Adds the given item to the multiset and returns how many of the item
+	 * the multiset now contains.
+	 */
+	public int add(T t) {
+		Integer count = map.get(t);
+		if (count == null) count = 0;
+		map.put(t, count + 1);
+		total++;
+		return count + 1;
+	}
+
+	/**
+	 * Removes the given item from the multiset and returns how many of the
+	 * item the multiset now contains.
+	 * @throws NoSuchElementException if the item is not in the multiset.
+	 */
+	public int remove(T t) {
+		Integer count = map.get(t);
+		if (count == null) throw new NoSuchElementException();
+		if (count == 1) map.remove(t);
+		else map.put(t, count - 1);
+		total--;
+		return count - 1;
+	}
+
+	/**
+	 * Removes all occurrences of the given item from the multiset.
+	 */
+	public int removeAll(T t) {
+		Integer count = map.remove(t);
+		if (count == null) return 0;
+		total -= count;
+		return count;
+	}
+
+	/**
+	 * Returns true if the multiset contains any occurrences of the given item.
+	 */
+	public boolean contains(T t) {
+		return map.containsKey(t);
+	}
+
+	/**
+	 * Removes all items from the multiset.
+	 */
+	public void clear() {
+		map.clear();
+		total = 0;
+	}
+
+	/**
+	 * Returns the set of unique items the multiset contains. The returned set
+	 * is unmodifiable.
+	 */
+	public Set<T> keySet() {
+		return Collections.unmodifiableSet(map.keySet());
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/UnsupportedVersionException.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api;
+
+import java.io.IOException;
+
+/**
+ * An exception that indicates an unrecoverable version mismatch.
+ */
+public class UnsupportedVersionException extends IOException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
@@ -93,10 +94,13 @@ public interface ClientHelper {
 
 	BdfList toList(Message m) throws FormatException;
 
+	BdfList toList(Author a);
+
 	byte[] sign(String label, BdfList toSign, byte[] privateKey)
 			throws FormatException, GeneralSecurityException;
 
 	void verifySignature(String label, byte[] sig, byte[] publicKey,
 			BdfList signed) throws FormatException, GeneralSecurityException;
 
+	Author parseAndValidateAuthor(BdfList author) throws FormatException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupFactory.java

@@ -12,18 +12,19 @@ public interface ContactGroupFactory {
 	/**
 	 * Creates a group that is not shared with any contacts.
 	 */
-	Group createLocalGroup(ClientId clientId);
+	Group createLocalGroup(ClientId clientId, int clientVersion);
 
 	/**
 	 * Creates a group for the given client to share with the given contact.
 	 */
-	Group createContactGroup(ClientId clientId, Contact contact);
+	Group createContactGroup(ClientId clientId, int clientVersion,
+			Contact contact);
 
 	/**
 	 * Creates a group for the given client to share between the given authors
 	 * identified by their AuthorIds.
 	 */
-	Group createContactGroup(ClientId clientId, AuthorId authorId1,
-			AuthorId authorId2);
+	Group createContactGroup(ClientId clientId, int clientVersion,
+			AuthorId authorId1, AuthorId authorId2);
 
 }

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeTask.java

@@ -12,6 +12,32 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 @NotNullByDefault
 public interface ContactExchangeTask {
 
+	/**
+	 * The current version of the contact exchange protocol
+	 */
+	int PROTOCOL_VERSION = 0;
+
+	/**
+	 * Label for deriving Alice's header key from the master secret.
+	 */
+	String ALICE_KEY_LABEL =
+			"org.briarproject.bramble.contact/ALICE_HEADER_KEY";
+
+	/**
+	 * Label for deriving Bob's header key from the master secret.
+	 */
+	String BOB_KEY_LABEL = "org.briarproject.bramble.contact/BOB_HEADER_KEY";
+
+	/**
+	 * Label for deriving Alice's key binding nonce from the master secret.
+	 */
+	String ALICE_NONCE_LABEL = "org.briarproject.bramble.contact/ALICE_NONCE";
+
+	/**
+	 * Label for deriving Bob's key binding nonce from the master secret.
+	 */
+	String BOB_NONCE_LABEL = "org.briarproject.bramble.contact/BOB_NONCE";
+
 	/**
 	 * Exchanges contact information with a remote peer.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java

@@ -1,11 +1,13 @@
 package org.briarproject.bramble.api.crypto;
 
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.transport.TransportKeys;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
 import java.security.SecureRandom;
 
+import javax.annotation.Nullable;
+
+@NotNullByDefault
 public interface CryptoComponent {
 
 	SecretKey generateSecretKey();
@@ -23,127 +25,46 @@ public interface CryptoComponent {
 	KeyParser getMessageKeyParser();
 
 	/**
-	 * Derives a stream header key from the given master secret.
-	 * @param alice whether the key is for use by Alice or Bob.
-	 */
-	SecretKey deriveHeaderKey(SecretKey master, boolean alice);
-
-	/**
-	 * Derives a message authentication code key from the given master secret.
-	 * @param alice whether the key is for use by Alice or Bob.
-	 */
-	SecretKey deriveMacKey(SecretKey master, boolean alice);
-
-	/**
-	 * Derives a nonce from the given master secret for one of the parties to
-	 * sign.
-	 * @param alice whether the nonce is for use by Alice or Bob.
-	 */
-	byte[] deriveSignatureNonce(SecretKey master, boolean alice);
-
-	/**
-	 * Derives a commitment to the provided public key.
-	 * <p/>
-	 * Part of BQP.
+	 * Derives another secret key from the given secret key.
 	 *
-	 * @param publicKey the public key
-	 * @return the commitment to the provided public key.
+	 * @param label a namespaced label indicating the purpose of the derived
+	 * key, to prevent it from being repurposed or colliding with a key derived
+	 * for another purpose
 	 */
-	byte[] deriveKeyCommitment(byte[] publicKey);
+	SecretKey deriveKey(String label, SecretKey k, byte[]... inputs);
 
 	/**
 	 * Derives a common shared secret from two public keys and one of the
 	 * corresponding private keys.
-	 * <p/>
-	 * Part of BQP.
 	 *
-	 * @param theirPublicKey the ephemeral public key of the remote party
-	 * @param ourKeyPair our ephemeral keypair
-	 * @param alice true if ourKeyPair belongs to Alice
+	 * @param label a namespaced label indicating the purpose of this shared
+	 * secret, to prevent it from being repurposed or colliding with a shared
+	 * secret derived for another purpose
+	 * @param theirPublicKey the public key of the remote party
+	 * @param ourKeyPair the key pair of the local party
 	 * @return the shared secret
-	 * @throws GeneralSecurityException
 	 */
-	SecretKey deriveSharedSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
-			boolean alice) throws GeneralSecurityException;
+	SecretKey deriveSharedSecret(String label, PublicKey theirPublicKey,
+			KeyPair ourKeyPair, byte[]... inputs)
+			throws GeneralSecurityException;
 
 	/**
-	 * Derives the content of a confirmation record.
-	 * <p/>
-	 * Part of BQP.
+	 * Signs the given byte[] with the given private key.
 	 *
-	 * @param sharedSecret the common shared secret
-	 * @param theirPayload the commit payload from the remote party
-	 * @param ourPayload the commit payload we sent
-	 * @param theirPublicKey the ephemeral public key of the remote party
-	 * @param ourKeyPair our ephemeral keypair
-	 * @param alice true if ourKeyPair belongs to Alice
-	 * @param aliceRecord true if the confirmation record is for use by Alice
-	 * @return the confirmation record
-	 */
-	byte[] deriveConfirmationRecord(SecretKey sharedSecret,
-			byte[] theirPayload, byte[] ourPayload,
-			byte[] theirPublicKey, KeyPair ourKeyPair,
-			boolean alice, boolean aliceRecord);
-
-	/**
-	 * Derives a master secret from the given shared secret.
-	 * <p/>
-	 * Part of BQP.
-	 *
-	 * @param sharedSecret the common shared secret
-	 * @return the master secret
-	 */
-	SecretKey deriveMasterSecret(SecretKey sharedSecret);
-
-	/**
-	 * Derives a master secret from two public keys and one of the corresponding
-	 * private keys.
-	 * <p/>
-	 * This is a helper method that calls
-	 * deriveMasterSecret(deriveSharedSecret(theirPublicKey, ourKeyPair, alice))
-	 *
-	 * @param theirPublicKey the ephemeral public key of the remote party
-	 * @param ourKeyPair our ephemeral keypair
-	 * @param alice true if ourKeyPair belongs to Alice
-	 * @return the shared secret
-	 * @throws GeneralSecurityException
-	 */
-	SecretKey deriveMasterSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
-			boolean alice) throws GeneralSecurityException;
-
-	/**
-	 * Derives initial transport keys for the given transport in the given
-	 * rotation period from the given master secret.
-	 * @param alice whether the keys are for use by Alice or Bob.
-	 */
-	TransportKeys deriveTransportKeys(TransportId t, SecretKey master,
-			long rotationPeriod, boolean alice);
-
-	/**
-	 * Rotates the given transport keys to the given rotation period. If the
-	 * keys are for a future rotation period they are not rotated.
-	 */
-	TransportKeys rotateTransportKeys(TransportKeys k, long rotationPeriod);
-
-	/** Encodes the pseudo-random tag that is used to recognise a stream. */
-	void encodeTag(byte[] tag, SecretKey tagKey, int protocolVersion,
-			long streamNumber);
-
-	/**
-	 * Signs the given byte[] with the given PrivateKey.
-	 *
-	 * @param label A label specific to this signature
-	 *              to ensure that the signature cannot be repurposed
+	 * @param label a namespaced label indicating the purpose of this
+	 * signature, to prevent it from being repurposed or colliding with a
+	 * signature created for another purpose
 	 */
 	byte[] sign(String label, byte[] toSign, byte[] privateKey)
 			throws GeneralSecurityException;
 
 	/**
-	 * Verifies that the given signature is valid for the signedData
-	 * and the given publicKey.
+	 * Verifies that the given signature is valid for the signed data
+	 * and the given public key.
 	 *
-	 * @param label A label that was specific to this signature
-	 *              to ensure that the signature cannot be repurposed
+	 * @param label a namespaced label indicating the purpose of this
+	 * signature, to prevent it from being repurposed or colliding with a
+	 * signature created for another purpose
 	 * @return true if the signature was valid, false otherwise.
 	 */
 	boolean verify(String label, byte[] signedData, byte[] publicKey,
@@ -153,23 +74,22 @@ public interface CryptoComponent {
 	 * Returns the hash of the given inputs. The inputs are unambiguously
 	 * combined by prefixing each input with its length.
 	 *
-	 * @param label A label specific to this hash to ensure that hashes
-	 *              calculated for distinct purposes don't collide.
+	 * @param label a namespaced label indicating the purpose of this hash, to
+	 * prevent it from being repurposed or colliding with a hash created for
+	 * another purpose
 	 */
 	byte[] hash(String label, byte[]... inputs);
 
-	/**
-	 * Returns the length of hashes produced by
-	 * the {@link CryptoComponent#hash(String, byte[]...)} method.
-	 */
-	int getHashLength();
-
 	/**
 	 * Returns a message authentication code with the given key over the
 	 * given inputs. The inputs are unambiguously combined by prefixing each
 	 * input with its length.
+	 *
+	 * @param label a namespaced label indicating the purpose of this MAC, to
+	 * prevent it from being repurposed or colliding with a MAC created for
+	 * another purpose
 	 */
-	byte[] mac(SecretKey macKey, byte[]... inputs);
+	byte[] mac(String label, SecretKey macKey, byte[]... inputs);
 
 	/**
 	 * Encrypts and authenticates the given plaintext so it can be written to
@@ -185,6 +105,7 @@ public interface CryptoComponent {
 	 * given password. Returns null if the ciphertext cannot be decrypted and
 	 * authenticated (for example, if the password is wrong).
 	 */
+	@Nullable
 	byte[] decryptWithPassword(byte[] ciphertext, String password);
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoConstants.java

@@ -0,0 +1,19 @@
+package org.briarproject.bramble.api.crypto;
+
+public interface CryptoConstants {
+
+	/**
+	 * The maximum length of an agreement public key in bytes.
+	 */
+	int MAX_AGREEMENT_PUBLIC_KEY_BYTES = 32;
+
+	/**
+	 * The maximum length of a signature public key in bytes.
+	 */
+	int MAX_SIGNATURE_PUBLIC_KEY_BYTES = 32;
+
+	/**
+	 * The maximum length of a signature in bytes.
+	 */
+	int MAX_SIGNATURE_BYTES = 64;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/KeyAgreementCrypto.java

@@ -0,0 +1,50 @@
+package org.briarproject.bramble.api.crypto;
+
+/**
+ * Crypto operations for the key agreement protocol - see
+ * https://code.briarproject.org/akwizgran/briar-spec/blob/master/protocols/BQP.md
+ */
+public interface KeyAgreementCrypto {
+
+	/**
+	 * Hash label for public key commitment.
+	 */
+	String COMMIT_LABEL = "org.briarproject.bramble.keyagreement/COMMIT";
+
+	/**
+	 * Key derivation label for confirmation record.
+	 */
+	String CONFIRMATION_KEY_LABEL =
+			"org.briarproject.bramble.keyagreement/CONFIRMATION_KEY";
+
+	/**
+	 * MAC label for confirmation record.
+	 */
+	String CONFIRMATION_MAC_LABEL =
+			"org.briarproject.bramble.keyagreement/CONFIRMATION_MAC";
+
+	/**
+	 * Derives a commitment to the provided public key.
+	 *
+	 * @param publicKey the public key
+	 * @return the commitment to the provided public key.
+	 */
+	byte[] deriveKeyCommitment(PublicKey publicKey);
+
+	/**
+	 * Derives the content of a confirmation record.
+	 *
+	 * @param sharedSecret the common shared secret
+	 * @param theirPayload the key exchange payload of the remote party
+	 * @param ourPayload the key exchange payload of the local party
+	 * @param theirPublicKey the ephemeral public key of the remote party
+	 * @param ourKeyPair our ephemeral key pair of the local party
+	 * @param alice true if the local party is Alice
+	 * @param aliceRecord true if the confirmation record is for use by Alice
+	 * @return the confirmation record
+	 */
+	byte[] deriveConfirmationRecord(SecretKey sharedSecret,
+			byte[] theirPayload, byte[] ourPayload,
+			PublicKey theirPublicKey, KeyPair ourKeyPair,
+			boolean alice, boolean aliceRecord);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/TransportCrypto.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.transport.TransportKeys;
+
+/**
+ * Crypto operations for the transport security protocol - see
+ * https://code.briarproject.org/akwizgran/briar-spec/blob/master/protocols/BTP.md
+ */
+public interface TransportCrypto {
+
+	/**
+	 * Derives initial transport keys for the given transport in the given
+	 * rotation period from the given master secret.
+	 *
+	 * @param alice whether the keys are for use by Alice or Bob.
+	 */
+	TransportKeys deriveTransportKeys(TransportId t, SecretKey master,
+			long rotationPeriod, boolean alice);
+
+	/**
+	 * Rotates the given transport keys to the given rotation period. If the
+	 * keys are for the given period or any later period they are not rotated.
+	 */
+	TransportKeys rotateTransportKeys(TransportKeys k, long rotationPeriod);
+
+	/**
+	 * Encodes the pseudo-random tag that is used to recognise a stream.
+	 */
+	void encodeTag(byte[] tag, SecretKey tagKey, int protocolVersion,
+			long streamNumber);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/data/ObjectReader.java

@@ -1,11 +0,0 @@
-package org.briarproject.bramble.api.data;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.io.IOException;
-
-@NotNullByDefault
-public interface ObjectReader<T> {
-
-	T readObject(BdfReader r) throws IOException;
-}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/Author.java

@@ -1,11 +1,13 @@
 package org.briarproject.bramble.api.identity;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.io.UnsupportedEncodingException;
+import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
+
 /**
  * A pseudonym for a user.
  */
@@ -17,20 +19,25 @@ public class Author {
 		NONE, ANONYMOUS, UNKNOWN, UNVERIFIED, VERIFIED, OURSELVES
 	}
 
+	/**
+	 * The current version of the author structure.
+	 */
+	public static final int FORMAT_VERSION = 1;
+
 	private final AuthorId id;
+	private final int formatVersion;
 	private final String name;
 	private final byte[] publicKey;
 
-	public Author(AuthorId id, String name, byte[] publicKey) {
-		int length;
-		try {
-			length = name.getBytes("UTF-8").length;
-		} catch (UnsupportedEncodingException e) {
-			throw new RuntimeException(e);
-		}
-		if (length == 0 || length > AuthorConstants.MAX_AUTHOR_NAME_LENGTH)
+	public Author(AuthorId id, int formatVersion, String name,
+			byte[] publicKey) {
+		int nameLength = StringUtils.toUtf8(name).length;
+		if (nameLength == 0 || nameLength > MAX_AUTHOR_NAME_LENGTH)
+			throw new IllegalArgumentException();
+		if (publicKey.length == 0 || publicKey.length > MAX_PUBLIC_KEY_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;
+		this.formatVersion = formatVersion;
 		this.name = name;
 		this.publicKey = publicKey;
 	}
@@ -42,6 +49,13 @@ public class Author {
 		return id;
 	}
 
+	/**
+	 * Returns the version of the author structure used to create the author.
+	 */
+	public int getFormatVersion() {
+		return formatVersion;
+	}
+
 	/**
 	 * Returns the author's name.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorConstants.java

@@ -1,5 +1,8 @@
 package org.briarproject.bramble.api.identity;
 
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_BYTES;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_PUBLIC_KEY_BYTES;
+
 public interface AuthorConstants {
 
 	/**
@@ -8,26 +11,14 @@ public interface AuthorConstants {
 	int MAX_AUTHOR_NAME_LENGTH = 50;
 
 	/**
-	 * The maximum length of a public key in bytes.
-	 * <p>
-	 * Public keys use SEC1 format: 0x04 x y, where x and y are unsigned
-	 * big-endian integers.
-	 * <p>
-	 * For a 256-bit elliptic curve, the maximum length is 2 * 256 / 8 + 1.
+	 * The maximum length of a public key in bytes. This applies to the
+	 * signature algorithm used by the current {@link Author format version}.
 	 */
-	int MAX_PUBLIC_KEY_LENGTH = 65;
+	int MAX_PUBLIC_KEY_LENGTH = MAX_SIGNATURE_PUBLIC_KEY_BYTES;
 
 	/**
-	 * The maximum length of a signature in bytes.
-	 * <p>
-	 * A signature is an ASN.1 DER sequence containing two integers, r and s.
-	 * The format is 0x30 len1 0x02 len2 r 0x02 len3 s, where len1 is
-	 * len(0x02 len2 r 0x02 len3 s) as a DER length, len2 is len(r) as a DER
-	 * length, len3 is len(s) as a DER length, and r and s are signed
-	 * big-endian integers of minimal length.
-	 * <p>
-	 * For a 256-bit elliptic curve, the lengths are one byte each, so the
-	 * maximum length is 2 * 256 / 8 + 8.
+	 * The maximum length of a signature in bytes. This applies to the
+	 * signature algorithm used by the current {@link Author format version}.
 	 */
-	int MAX_SIGNATURE_LENGTH = 72;
+	int MAX_SIGNATURE_LENGTH = MAX_SIGNATURE_BYTES;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorFactory.java

@@ -5,8 +5,27 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 @NotNullByDefault
 public interface AuthorFactory {
 
+	/**
+	 * Creates an author with the current format version and the given name and
+	 * public key.
+	 */
 	Author createAuthor(String name, byte[] publicKey);
 
+	/**
+	 * Creates an author with the given format version, name and public key.
+	 */
+	Author createAuthor(int formatVersion, String name, byte[] publicKey);
+
+	/**
+	 * Creates a local author with the current format version and the given
+	 * name and keys.
+	 */
 	LocalAuthor createLocalAuthor(String name, byte[] publicKey,
 			byte[] privateKey);
+
+	/**
+	 * Creates a local author with the given format version, name and keys.
+	 */
+	LocalAuthor createLocalAuthor(int formatVersion, String name,
+			byte[] publicKey, byte[] privateKey);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorId.java

@@ -16,7 +16,7 @@ public class AuthorId extends UniqueId {
 	/**
 	 * Label for hashing authors to calculate their identities.
 	 */
-	public static final String LABEL = "org.briarproject.bramble.AUTHOR_ID";
+	public static final String LABEL = "org.briarproject.bramble/AUTHOR_ID";
 
 	public AuthorId(byte[] id) {
 		super(id);

bramble-api/src/main/java/org/briarproject/bramble/api/identity/LocalAuthor.java

@@ -14,9 +14,9 @@ public class LocalAuthor extends Author {
 	private final byte[] privateKey;
 	private final long created;
 
-	public LocalAuthor(AuthorId id, String name, byte[] publicKey,
-			byte[] privateKey, long created) {
-		super(id, name, publicKey);
+	public LocalAuthor(AuthorId id, int formatVersion, String name,
+			byte[] publicKey, byte[] privateKey, long created) {
+		super(id, formatVersion, name, publicKey);
 		this.privateKey = privateKey;
 		this.created = created;
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementConstants.java

@@ -3,9 +3,9 @@ package org.briarproject.bramble.api.keyagreement;
 public interface KeyAgreementConstants {
 
 	/**
-	 * The current version of the BQP protocol.
+	 * The current version of the BQP protocol. Version number 89 is reserved.
 	 */
-	byte PROTOCOL_VERSION = 2;
+	byte PROTOCOL_VERSION = 4;
 
 	/**
 	 * The length of the record header in bytes.
@@ -22,7 +22,10 @@ public interface KeyAgreementConstants {
 	 */
 	int COMMIT_LENGTH = 16;
 
-	long CONNECTION_TIMEOUT = 20 * 1000; // Milliseconds
+	/**
+	 * The connection timeout in milliseconds.
+	 */
+	long CONNECTION_TIMEOUT = 20 * 1000;
 
 	/**
 	 * The transport identifier for Bluetooth.
@@ -33,4 +36,16 @@ public interface KeyAgreementConstants {
 	 * The transport identifier for LAN.
 	 */
 	int TRANSPORT_ID_LAN = 1;
+
+	/**
+	 * Label for deriving the shared secret.
+	 */
+	String SHARED_SECRET_LABEL =
+			"org.briarproject.bramble.keyagreement/SHARED_SECRET";
+
+	/**
+	 * Label for deriving the master secret.
+	 */
+	String MASTER_SECRET_LABEL =
+			"org.briarproject.bramble.keyagreement/MASTER_SECRET";
 }

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementTaskFactory.java

@@ -1,15 +0,0 @@
-package org.briarproject.bramble.api.keyagreement;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-/**
- * Manages tasks for conducting key agreements with remote peers.
- */
-@NotNullByDefault
-public interface KeyAgreementTaskFactory {
-
-	/**
-	 * Gets the current key agreement task.
-	 */
-	KeyAgreementTask createTask();
-}

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java

@@ -17,6 +17,11 @@ public interface TransportPropertyManager {
 	 */
 	ClientId CLIENT_ID = new ClientId("org.briarproject.briar.properties");
 
+	/**
+	 * The current version of the transport property client.
+	 */
+	int CLIENT_VERSION = 0;
+
 	/**
 	 * Stores the given properties received while adding a contact - they will
 	 * be superseded by any properties synced from the contact.

bramble-api/src/main/java/org/briarproject/bramble/api/sync/ClientId.java

@@ -36,4 +36,8 @@ public class ClientId implements Comparable<ClientId> {
 		return id.hashCode();
 	}
 
+	@Override
+	public String toString() {
+		return id;
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/GroupFactory.java

@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 public interface GroupFactory {
 
 	/**
-	 * Creates a group with the given client ID and descriptor.
+	 * Creates a group with the given client ID, client version and descriptor.
 	 */
-	Group createGroup(ClientId c, byte[] descriptor);
+	Group createGroup(ClientId c, int clientVersion, byte[] descriptor);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/GroupId.java

@@ -15,7 +15,7 @@ public class GroupId extends UniqueId {
 	/**
 	 * Label for hashing groups to calculate their identifiers.
 	 */
-	public static final String LABEL = "org.briarproject.bramble.GROUP_ID";
+	public static final String LABEL = "org.briarproject.bramble/GROUP_ID";
 
 	public GroupId(byte[] id) {
 		super(id);

bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageId.java

@@ -16,7 +16,7 @@ public class MessageId extends UniqueId {
 	/**
 	 * Label for hashing messages to calculate their identifiers.
 	 */
-	public static final String LABEL = "org.briarproject.bramble.MESSAGE_ID";
+	public static final String LABEL = "org.briarproject.bramble/MESSAGE_ID";
 
 	public MessageId(byte[] id) {
 		super(id);

bramble-api/src/main/java/org/briarproject/bramble/api/transport/TransportConstants.java

@@ -7,7 +7,7 @@ public interface TransportConstants {
 	/**
 	 * The current version of the transport protocol.
 	 */
-	int PROTOCOL_VERSION = 3;
+	int PROTOCOL_VERSION = 4;
 
 	/**
 	 * The length of the pseudo-random tag in bytes.
@@ -80,4 +80,32 @@ public interface TransportConstants {
 	 * The size of the reordering window.
 	 */
 	int REORDERING_WINDOW_SIZE = 32;
+
+	/**
+	 * Label for deriving Alice's initial tag key from the master secret.
+	 */
+	String ALICE_TAG_LABEL = "org.briarproject.bramble.transport/ALICE_TAG_KEY";
+
+	/**
+	 * Label for deriving Bob's initial tag key from the master secret.
+	 */
+	String BOB_TAG_LABEL = "org.briarproject.bramble.transport/BOB_TAG_KEY";
+
+	/**
+	 * Label for deriving Alice's initial header key from the master secret.
+	 */
+	String ALICE_HEADER_LABEL =
+			"org.briarproject.bramble.transport/ALICE_HEADER_KEY";
+
+	/**
+	 * Label for deriving Bob's initial header key from the master secret.
+	 */
+	String BOB_HEADER_LABEL =
+			"org.briarproject.bramble.transport/BOB_HEADER_KEY";
+
+	/**
+	 * Label for deriving the next period's key in key rotation.
+	 */
+	String ROTATE_LABEL = "org.briarproject.bramble.transport/ROTATE";
+
 }

bramble-api/src/main/java/org/briarproject/bramble/util/StringUtils.java

@@ -146,6 +146,14 @@ public class StringUtils {
 		return s.toString();
 	}
 
+	public static String ipToString(int ip) {
+		int ip1 = ip & 0xFF;
+		int ip2 = (ip >> 8) & 0xFF;
+		int ip3 = (ip >> 16) & 0xFF;
+		int ip4 = (ip >> 24) & 0xFF;
+		return ip1 + "." + ip2 + "." + ip3 + "." + ip4;
+	}
+
 	public static String getRandomString(int length) {
 		char[] c = new char[length];
 		for (int i = 0; i < length; i++)

bramble-api/src/test/java/org/briarproject/bramble/test/TestUtils.java

@@ -13,9 +13,14 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
@@ -63,7 +68,8 @@ public class TestUtils {
 		byte[] publicKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
 		byte[] privateKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
 		long created = System.currentTimeMillis();
-		return new LocalAuthor(id, name, publicKey, privateKey, created);
+		return new LocalAuthor(id, FORMAT_VERSION, name, publicKey, privateKey,
+				created);
 	}
 
 	public static Author getAuthor() {
@@ -74,7 +80,7 @@ public class TestUtils {
 		AuthorId id = new AuthorId(getRandomId());
 		String name = getRandomString(nameLength);
 		byte[] publicKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
-		return new Author(id, name, publicKey);
+		return new Author(id, FORMAT_VERSION, name, publicKey);
 	}
 
 	public static Group getGroup(ClientId clientId) {
@@ -99,4 +105,38 @@ public class TestUtils {
 		long timestamp = System.currentTimeMillis();
 		return new Message(id, groupId, timestamp, raw);
 	}
+
+	public static double getMedian(Collection<? extends Number> samples) {
+		int size = samples.size();
+		if (size == 0) throw new IllegalArgumentException();
+		List<Double> sorted = new ArrayList<>(size);
+		for (Number n : samples) sorted.add(n.doubleValue());
+		Collections.sort(sorted);
+		if (size % 2 == 1) return sorted.get(size / 2);
+		double low = sorted.get(size / 2 - 1), high = sorted.get(size / 2);
+		return (low + high) / 2;
+	}
+
+	public static double getMean(Collection<? extends Number> samples) {
+		if (samples.isEmpty()) throw new IllegalArgumentException();
+		double sum = 0;
+		for (Number n : samples) sum += n.doubleValue();
+		return sum / samples.size();
+	}
+
+	public static double getVariance(Collection<? extends Number> samples) {
+		if (samples.size() < 2) throw new IllegalArgumentException();
+		double mean = getMean(samples);
+		double sumSquareDiff = 0;
+		for (Number n : samples) {
+			double diff = n.doubleValue() - mean;
+			sumSquareDiff += diff * diff;
+		}
+		return sumSquareDiff / (samples.size() - 1);
+	}
+
+	public static double getStandardDeviation(
+			Collection<? extends Number> samples) {
+		return Math.sqrt(getVariance(samples));
+	}
 }

bramble-core/build.gradle

@@ -9,12 +9,15 @@ apply plugin: 'witness'
 dependencies {
 	implementation project(path: ':bramble-api', configuration: 'default')
 	implementation 'com.madgag.spongycastle:core:1.58.0.0'
-	implementation 'com.h2database:h2:1.4.192' // This is the last version that supports Java 1.6
+	implementation 'com.h2database:h2:1.4.192' // The last version that supports Java 1.6
 	implementation 'org.bitlet:weupnp:0.1.4'
+	implementation 'net.i2p.crypto:eddsa:0.2.0'
+	implementation 'org.whispersystems:curve25519-java:0.4.1'
 
 	apt 'com.google.dagger:dagger-compiler:2.0.2'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
+	testImplementation 'org.hsqldb:hsqldb:2.3.5' // The last version that supports Java 1.6
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
@@ -37,18 +40,21 @@ dependencyVerification {
 			'com.madgag.spongycastle:core:1.58.0.0:core-1.58.0.0.jar:199617dd5698c5a9312b898c0a4cec7ce9dd8649d07f65d91629f58229d72728',
 			'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
 			'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
+			'net.i2p.crypto:eddsa:0.2.0:eddsa-0.2.0.jar:a7cb1b85c16e2f0730b9204106929a1d9aaae1df728adc7041a8b8b605692140',
 			'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
 			'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
 			'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
 			'org.bitlet:weupnp:0.1.4:weupnp-0.1.4.jar:88df7e6504929d00bdb832863761385c68ab92af945b04f0770b126270a444fb',
 			'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
 			'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
+			'org.hsqldb:hsqldb:2.3.5:hsqldb-2.3.5.jar:6676a6977ac98997a80f827ddbd3fe8ca1e0853dad1492512135fd1a222ccfad',
 			'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
 			'org.jmock:jmock-legacy:2.8.2:jmock-legacy-2.8.2.jar:f2b985a5c08a9edb7f37612330c058809da3f6a6d63ce792426ebf8ff0d6d31b',
 			'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
 			'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
 			'org.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
 			'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
+			'org.whispersystems:curve25519-java:0.4.1:curve25519-java-0.4.1.jar:7dd659d8822c06c3aea1a47f18fac9e5761e29cab8100030b877db445005f03e',
 	]
 }
 

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -15,6 +15,8 @@ import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
@@ -32,7 +34,12 @@ import java.util.Map.Entry;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
+import static org.briarproject.bramble.util.ValidationUtils.checkLength;
+import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 
 @Immutable
 @NotNullByDefault
@@ -51,12 +58,14 @@ class ClientHelperImpl implements ClientHelper {
 	private final MetadataParser metadataParser;
 	private final MetadataEncoder metadataEncoder;
 	private final CryptoComponent crypto;
+	private final AuthorFactory authorFactory;
 
 	@Inject
 	ClientHelperImpl(DatabaseComponent db, MessageFactory messageFactory,
 			BdfReaderFactory bdfReaderFactory,
 			BdfWriterFactory bdfWriterFactory, MetadataParser metadataParser,
-			MetadataEncoder metadataEncoder, CryptoComponent crypto) {
+			MetadataEncoder metadataEncoder, CryptoComponent crypto,
+			AuthorFactory authorFactory) {
 		this.db = db;
 		this.messageFactory = messageFactory;
 		this.bdfReaderFactory = bdfReaderFactory;
@@ -64,6 +73,7 @@ class ClientHelperImpl implements ClientHelper {
 		this.metadataParser = metadataParser;
 		this.metadataEncoder = metadataEncoder;
 		this.crypto = crypto;
+		this.authorFactory = authorFactory;
 	}
 
 	@Override
@@ -341,6 +351,11 @@ class ClientHelperImpl implements ClientHelper {
 				raw.length - MESSAGE_HEADER_LENGTH);
 	}
 
+	@Override
+	public BdfList toList(Author a) {
+		return BdfList.of(a.getFormatVersion(), a.getName(), a.getPublicKey());
+	}
+
 	@Override
 	public byte[] sign(String label, BdfList toSign, byte[] privateKey)
 			throws FormatException, GeneralSecurityException {
@@ -355,4 +370,16 @@ class ClientHelperImpl implements ClientHelper {
 		}
 	}
 
+	@Override
+	public Author parseAndValidateAuthor(BdfList author)
+			throws FormatException {
+		checkSize(author, 3);
+		int formatVersion = author.getLong(0).intValue();
+		if (formatVersion != FORMAT_VERSION) throw new FormatException();
+		String name = author.getString(1);
+		checkLength(name, 1, MAX_AUTHOR_NAME_LENGTH);
+		byte[] publicKey = author.getRaw(2);
+		checkLength(publicKey, 1, MAX_PUBLIC_KEY_LENGTH);
+		return authorFactory.createAuthor(formatVersion, name, publicKey);
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/client/ClientModule.java

@@ -2,14 +2,6 @@ package org.briarproject.bramble.client;
 
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.client.ContactGroupFactory;
-import org.briarproject.bramble.api.crypto.CryptoComponent;
-import org.briarproject.bramble.api.data.BdfReaderFactory;
-import org.briarproject.bramble.api.data.BdfWriterFactory;
-import org.briarproject.bramble.api.data.MetadataEncoder;
-import org.briarproject.bramble.api.data.MetadataParser;
-import org.briarproject.bramble.api.db.DatabaseComponent;
-import org.briarproject.bramble.api.sync.GroupFactory;
-import org.briarproject.bramble.api.sync.MessageFactory;
 
 import dagger.Module;
 import dagger.Provides;
@@ -18,19 +10,14 @@ import dagger.Provides;
 public class ClientModule {
 
 	@Provides
-	ClientHelper provideClientHelper(DatabaseComponent db,
-			MessageFactory messageFactory, BdfReaderFactory bdfReaderFactory,
-			BdfWriterFactory bdfWriterFactory, MetadataParser metadataParser,
-			MetadataEncoder metadataEncoder, CryptoComponent cryptoComponent) {
-		return new ClientHelperImpl(db, messageFactory, bdfReaderFactory,
-				bdfWriterFactory, metadataParser, metadataEncoder,
-				cryptoComponent);
+	ClientHelper provideClientHelper(ClientHelperImpl clientHelper) {
+		return clientHelper;
 	}
 
 	@Provides
-	ContactGroupFactory provideContactGroupFactory(GroupFactory groupFactory,
-			ClientHelper clientHelper) {
-		return new ContactGroupFactoryImpl(groupFactory, clientHelper);
+	ContactGroupFactory provideContactGroupFactory(
+			ContactGroupFactoryImpl contactGroupFactory) {
+		return contactGroupFactory;
 	}
 
 }

bramble-core/src/main/java/org/briarproject/bramble/client/ContactGroupFactoryImpl.java

@@ -32,23 +32,25 @@ class ContactGroupFactoryImpl implements ContactGroupFactory {
 	}
 
 	@Override
-	public Group createLocalGroup(ClientId clientId) {
-		return groupFactory.createGroup(clientId, LOCAL_GROUP_DESCRIPTOR);
+	public Group createLocalGroup(ClientId clientId, int clientVersion) {
+		return groupFactory.createGroup(clientId, clientVersion,
+				LOCAL_GROUP_DESCRIPTOR);
 	}
 
 	@Override
-	public Group createContactGroup(ClientId clientId, Contact contact) {
+	public Group createContactGroup(ClientId clientId, int clientVersion,
+			Contact contact) {
 		AuthorId local = contact.getLocalAuthorId();
 		AuthorId remote = contact.getAuthor().getId();
 		byte[] descriptor = createGroupDescriptor(local, remote);
-		return groupFactory.createGroup(clientId, descriptor);
+		return groupFactory.createGroup(clientId, clientVersion, descriptor);
 	}
 
 	@Override
-	public Group createContactGroup(ClientId clientId, AuthorId authorId1,
-			AuthorId authorId2) {
+	public Group createContactGroup(ClientId clientId, int clientVersion,
+			AuthorId authorId1, AuthorId authorId2) {
 		byte[] descriptor = createGroupDescriptor(authorId1, authorId2);
-		return groupFactory.createGroup(clientId, descriptor);
+		return groupFactory.createGroup(clientId, clientVersion, descriptor);
 	}
 
 	private byte[] createGroupDescriptor(AuthorId local, AuthorId remote) {

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeTaskImpl.java

@@ -43,6 +43,7 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
@@ -141,8 +142,10 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		}
 
 		// Derive the header keys for the transport streams
-		SecretKey aliceHeaderKey = crypto.deriveHeaderKey(masterSecret, true);
-		SecretKey bobHeaderKey = crypto.deriveHeaderKey(masterSecret, false);
+		SecretKey aliceHeaderKey = crypto.deriveKey(ALICE_KEY_LABEL,
+				masterSecret, new byte[] {PROTOCOL_VERSION});
+		SecretKey bobHeaderKey = crypto.deriveKey(BOB_KEY_LABEL, masterSecret,
+				new byte[] {PROTOCOL_VERSION});
 
 		// Create the readers
 		InputStream streamReader =
@@ -156,8 +159,10 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		BdfWriter w = bdfWriterFactory.createWriter(streamWriter);
 
 		// Derive the nonces to be signed
-		byte[] aliceNonce = crypto.deriveSignatureNonce(masterSecret, true);
-		byte[] bobNonce = crypto.deriveSignatureNonce(masterSecret, false);
+		byte[] aliceNonce = crypto.mac(ALICE_NONCE_LABEL, masterSecret,
+				new byte[] {PROTOCOL_VERSION});
+		byte[] bobNonce = crypto.mac(BOB_NONCE_LABEL, masterSecret,
+				new byte[] {PROTOCOL_VERSION});
 
 		// Exchange pseudonyms, signed nonces, and timestamps
 		long localTimestamp = clock.currentTimeMillis();
@@ -196,8 +201,8 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 
 		try {
 			// Add the contact
-			ContactId contactId = addContact(remoteAuthor, masterSecret,
-					timestamp, alice, remoteProperties);
+			ContactId contactId = addContact(remoteAuthor, timestamp,
+					remoteProperties);
 			// Reuse the connection as a transport connection
 			connectionManager.manageOutgoingConnection(contactId, transportId,
 					conn);
@@ -223,6 +228,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 
 		// Write the name, public key and signature
 		w.writeListStart();
+		w.writeLong(localAuthor.getFormatVersion());
 		w.writeString(localAuthor.getName());
 		w.writeRaw(localAuthor.getPublicKey());
 		w.writeRaw(sig);
@@ -232,11 +238,16 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 
 	private Author receivePseudonym(BdfReader r, byte[] nonce)
 			throws GeneralSecurityException, IOException {
-		// Read the name, public key and signature
+		// Read the format version, name, public key and signature
 		r.readListStart();
+		int formatVersion = (int) r.readLong();
+		if (formatVersion != FORMAT_VERSION) throw new FormatException();
 		String name = r.readString(MAX_AUTHOR_NAME_LENGTH);
+		if (name.isEmpty()) throw new FormatException();
 		byte[] publicKey = r.readRaw(MAX_PUBLIC_KEY_LENGTH);
+		if (publicKey.length == 0) throw new FormatException();
 		byte[] sig = r.readRaw(MAX_SIGNATURE_LENGTH);
+		if (sig.length == 0) throw new FormatException();
 		r.readListEnd();
 		LOG.info("Received pseudonym");
 		// Verify the signature
@@ -245,7 +256,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 				LOG.info("Invalid signature");
 			throw new GeneralSecurityException();
 		}
-		return authorFactory.createAuthor(name, publicKey);
+		return authorFactory.createAuthor(formatVersion, name, publicKey);
 	}
 
 	private void sendTimestamp(BdfWriter w, long timestamp)
@@ -294,15 +305,15 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		return remote;
 	}
 
-	private ContactId addContact(Author remoteAuthor, SecretKey master,
-			long timestamp, boolean alice,
+	private ContactId addContact(Author remoteAuthor, long timestamp,
 			Map<TransportId, TransportProperties> remoteProperties)
 			throws DbException {
 		ContactId contactId;
 		Transaction txn = db.startTransaction(false);
 		try {
 			contactId = contactManager.addContact(txn, remoteAuthor,
-					localAuthor.getId(), master, timestamp, alice, true, true);
+					localAuthor.getId(), masterSecret, timestamp, alice,
+					true, true);
 			transportPropertyManager.addRemoteProperties(txn, contactId,
 					remoteProperties);
 			db.commitTransaction(txn);
@@ -312,8 +323,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		return contactId;
 	}
 
-	private void tryToClose(DuplexTransportConnection conn,
-			boolean exception) {
+	private void tryToClose(DuplexTransportConnection conn, boolean exception) {
 		try {
 			LOG.info("Closing connection");
 			conn.getReader().dispose(exception, true);

bramble-core/src/main/java/org/briarproject/bramble/crypto/Blake2sDigest.java

@@ -1,547 +0,0 @@
-package org.briarproject.bramble.crypto;
-
-/*
-  The BLAKE2 cryptographic hash function was designed by Jean-
-  Philippe Aumasson, Samuel Neves, Zooko Wilcox-O'Hearn, and Christian
-  Winnerlein.
-
-  Reference Implementation and Description can be found at: https://blake2.net/
-  RFC: https://tools.ietf.org/html/rfc7693
-
-  This implementation does not support the Tree Hashing Mode.
-
-  For unkeyed hashing, developers adapting BLAKE2 to ASN.1 - based
-  message formats SHOULD use the OID tree at x = 1.3.6.1.4.1.1722.12.2.
-
-         Algorithm     | Target | Collision | Hash | Hash ASN.1 |
-            Identifier |  Arch  |  Security |  nn  | OID Suffix |
-        ---------------+--------+-----------+------+------------+
-         id-blake2s128 | 32-bit |   2**64   |  16  |   x.2.4    |
-         id-blake2s160 | 32-bit |   2**80   |  20  |   x.2.5    |
-         id-blake2s224 | 32-bit |   2**112  |  28  |   x.2.7    |
-         id-blake2s256 | 32-bit |   2**128  |  32  |   x.2.8    |
-        ---------------+--------+-----------+------+------------+
-
-  Based on the BouncyCastle implementation of BLAKE2b. License:
-
-  Copyright (c) 2000 - 2015 The Legion of the Bouncy Castle Inc.
-  (http://www.bouncycastle.org)
-
-  Permission is hereby granted, free of charge, to any person obtaining a copy
-  of this software and associated documentation files (the "Software"), to deal
-  in the Software without restriction, including without limitation the rights
-  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-  copies of the Software, and to permit persons to whom the Software is
-  furnished to do so, subject to the following conditions:
-
-  The above copyright notice and this permission notice shall be included in
-  all copies or substantial portions of the Software.
-
-  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-  SOFTWARE.
- */
-
-import org.spongycastle.crypto.ExtendedDigest;
-import org.spongycastle.util.Arrays;
-
-/**
- * Implementation of the cryptographic hash function BLAKE2s.
- * <p/>
- * BLAKE2s offers a built-in keying mechanism to be used directly
- * for authentication ("Prefix-MAC") rather than a HMAC construction.
- * <p/>
- * BLAKE2s offers a built-in support for a salt for randomized hashing
- * and a personal string for defining a unique hash function for each application.
- * <p/>
- * BLAKE2s is optimized for 32-bit platforms and produces digests of any size
- * between 1 and 32 bytes.
- */
-public class Blake2sDigest implements ExtendedDigest {
-	/** BLAKE2s Initialization Vector **/
-	private static final int blake2s_IV[] =
-			// Produced from the square root of primes 2, 3, 5, 7, 11, 13, 17, 19.
-			// The same as SHA-256 IV.
-			{
-					0x6a09e667, 0xbb67ae85, 0x3c6ef372,
-					0xa54ff53a, 0x510e527f, 0x9b05688c,
-					0x1f83d9ab, 0x5be0cd19
-			};
-
-	/** Message word permutations **/
-	private static final byte[][] blake2s_sigma =
-			{
-					{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
-					{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
-					{ 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
-					{ 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
-					{ 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
-					{ 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
-					{ 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
-					{ 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
-					{ 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
-					{ 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 }
-			};
-
-	private static final int ROUNDS = 10; // to use for Catenas H'
-	private static final int BLOCK_LENGTH_BYTES = 64;// bytes
-
-	// General parameters:
-	private int digestLength = 32; // 1- 32 bytes
-	private int keyLength = 0; // 0 - 32 bytes for keyed hashing for MAC
-	private byte[] salt = null;
-	private byte[] personalization = null;
-	private byte[] key = null;
-
-	// Tree hashing parameters:
-	// Because this class does not implement the Tree Hashing Mode,
-	// these parameters can be treated as constants (see init() function)
-	/*
-	 * private int fanout = 1; // 0-255
-	 * private int depth = 1; // 1 - 255
-	 * private int leafLength= 0;
-	 * private long nodeOffset = 0L;
-	 * private int nodeDepth = 0;
-	 * private int innerHashLength = 0;
-	 */
-
-	/**
-	 * Whenever this buffer overflows, it will be processed in the compress()
-	 * function. For performance issues, long messages will not use this buffer.
-	 */
-	private byte[] buffer = null;
-	/** Position of last inserted byte **/
-	private int bufferPos = 0;// a value from 0 up to BLOCK_LENGTH_BYTES
-
-	/** Internal state, in the BLAKE2 paper it is called v **/
-	private int[] internalState = new int[16];
-	/** State vector, in the BLAKE2 paper it is called h **/
-	private int[] chainValue = null;
-
-	// counter (counts bytes): Length up to 2^64 are supported
-	/** holds least significant bits of counter **/
-	private int t0 = 0;
-	/** holds most significant bits of counter **/
-	private int t1 = 0;
-	/** finalization flag, for last block: ~0 **/
-	private int f0 = 0;
-
-	// For Tree Hashing Mode, not used here:
-	// private long f1 = 0L; // finalization flag, for last node: ~0L
-
-	/**
-	 * BLAKE2s-256 for hashing.
-	 */
-	public Blake2sDigest() {
-		this(256);
-	}
-
-	public Blake2sDigest(Blake2sDigest digest) {
-		this.bufferPos = digest.bufferPos;
-		this.buffer = Arrays.clone(digest.buffer);
-		this.keyLength = digest.keyLength;
-		this.key = Arrays.clone(digest.key);
-		this.digestLength = digest.digestLength;
-		this.chainValue = Arrays.clone(digest.chainValue);
-		this.personalization = Arrays.clone(digest.personalization);
-	}
-
-	/**
-	 * BLAKE2s for hashing.
-	 *
-	 * @param digestBits the desired digest length in bits. Must be one of
-	 *                     [128, 160, 224, 256].
-	 */
-	public Blake2sDigest(int digestBits) {
-		if (digestBits != 128 && digestBits != 160 &&
-				digestBits != 224 && digestBits != 256) {
-			throw new IllegalArgumentException(
-					"BLAKE2s digest restricted to one of [128, 160, 224, 256]");
-		}
-		buffer = new byte[BLOCK_LENGTH_BYTES];
-		keyLength = 0;
-		digestLength = digestBits / 8;
-		init();
-	}
-
-	/**
-	 * BLAKE2s for authentication ("Prefix-MAC mode").
-	 * <p/>
-	 * After calling the doFinal() method, the key will remain to be used for
-	 * further computations of this instance. The key can be overwritten using
-	 * the clearKey() method.
-	 *
-	 * @param key a key up to 32 bytes or null
-	 */
-	public Blake2sDigest(byte[] key) {
-		buffer = new byte[BLOCK_LENGTH_BYTES];
-		if (key != null) {
-			if (key.length > 32) {
-				throw new IllegalArgumentException(
-						"Keys > 32 are not supported");
-			}
-			this.key = new byte[key.length];
-			System.arraycopy(key, 0, this.key, 0, key.length);
-
-			keyLength = key.length;
-			System.arraycopy(key, 0, buffer, 0, key.length);
-			bufferPos = BLOCK_LENGTH_BYTES; // zero padding
-		}
-		digestLength = 32;
-		init();
-	}
-
-	/**
-	 * BLAKE2s with key, required digest length, salt and personalization.
-	 * <p/>
-	 * After calling the doFinal() method, the key, the salt and the personal
-	 * string will remain and might be used for further computations with this
-	 * instance. The key can be overwritten using the clearKey() method, the
-	 * salt (pepper) can be overwritten using the clearSalt() method.
-	 *
-	 * @param key a key up to 32 bytes or null
-	 * @param digestBytes from 1 up to 32 bytes
-	 * @param salt 8 bytes or null
-	 * @param personalization 8 bytes or null
-	 */
-	public Blake2sDigest(byte[] key, int digestBytes, byte[] salt,
-			byte[] personalization) {
-		buffer = new byte[BLOCK_LENGTH_BYTES];
-		if (digestBytes < 1 || digestBytes > 32) {
-			throw new IllegalArgumentException(
-					"Invalid digest length (required: 1 - 32)");
-		}
-		digestLength = digestBytes;
-		if (salt != null) {
-			if (salt.length != 8) {
-				throw new IllegalArgumentException(
-						"Salt length must be exactly 8 bytes");
-			}
-			this.salt = new byte[8];
-			System.arraycopy(salt, 0, this.salt, 0, salt.length);
-		}
-		if (personalization != null) {
-			if (personalization.length != 8) {
-				throw new IllegalArgumentException(
-						"Personalization length must be exactly 8 bytes");
-			}
-			this.personalization = new byte[8];
-			System.arraycopy(personalization, 0, this.personalization, 0,
-					personalization.length);
-		}
-		if (key != null) {
-			if (key.length > 32) {
-				throw new IllegalArgumentException(
-						"Keys > 32 bytes are not supported");
-			}
-			this.key = new byte[key.length];
-			System.arraycopy(key, 0, this.key, 0, key.length);
-
-			keyLength = key.length;
-			System.arraycopy(key, 0, buffer, 0, key.length);
-			bufferPos = BLOCK_LENGTH_BYTES; // zero padding
-		}
-		init();
-	}
-
-	// initialize chainValue
-	private void init() {
-		if (chainValue == null) {
-			chainValue = new int[8];
-
-			chainValue[0] = blake2s_IV[0]
-					^ (digestLength | (keyLength << 8) | 0x1010000);
-			// 0x1010000 = ((fanout << 16) | (depth << 24));
-			// with fanout = 1; depth = 0;
-			chainValue[1] = blake2s_IV[1];// ^ leafLength; with leafLength = 0;
-			chainValue[2] = blake2s_IV[2];// ^ nodeOffset; with nodeOffset = 0;
-			chainValue[3] = blake2s_IV[3];// ^ ( (nodeOffset << 32) |
-			// (nodeDepth << 16) | (innerHashLength << 24) );
-			// with nodeDepth = 0; innerHashLength = 0;
-
-			chainValue[4] = blake2s_IV[4];
-			chainValue[5] = blake2s_IV[5];
-			if (salt != null) {
-				chainValue[4] ^= (bytes2int(salt, 0));
-				chainValue[5] ^= (bytes2int(salt, 4));
-			}
-
-			chainValue[6] = blake2s_IV[6];
-			chainValue[7] = blake2s_IV[7];
-			if (personalization != null) {
-				chainValue[6] ^= (bytes2int(personalization, 0));
-				chainValue[7] ^= (bytes2int(personalization, 4));
-			}
-		}
-	}
-
-	private void initializeInternalState() {
-		// initialize v:
-		System.arraycopy(chainValue, 0, internalState, 0, chainValue.length);
-		System.arraycopy(blake2s_IV, 0, internalState, chainValue.length, 4);
-		internalState[12] = t0 ^ blake2s_IV[4];
-		internalState[13] = t1 ^ blake2s_IV[5];
-		internalState[14] = f0 ^ blake2s_IV[6];
-		internalState[15] = blake2s_IV[7];// ^ f1 with f1 = 0
-	}
-
-	/**
-	 * Update the message digest with a single byte.
-	 *
-	 * @param b the input byte to be entered.
-	 */
-	public void update(byte b) {
-		int remainingLength; // left bytes of buffer
-
-		// process the buffer if full else add to buffer:
-		remainingLength = BLOCK_LENGTH_BYTES - bufferPos;
-		if (remainingLength == 0) { // full buffer
-			t0 += BLOCK_LENGTH_BYTES;
-			if (t0 == 0) { // if message > 2^32
-				t1++;
-			}
-			compress(buffer, 0);
-			Arrays.fill(buffer, (byte)0);// clear buffer
-			buffer[0] = b;
-			bufferPos = 1;
-		} else {
-			buffer[bufferPos] = b;
-			bufferPos++;
-		}
-	}
-
-	/**
-	 * Update the message digest with a block of bytes.
-	 *
-	 * @param message the byte array containing the data.
-	 * @param offset the offset into the byte array where the data starts.
-	 * @param len the length of the data.
-	 */
-	public void update(byte[] message, int offset, int len) {
-		if (message == null || len == 0)
-			return;
-
-		int remainingLength = 0; // left bytes of buffer
-
-		if (bufferPos != 0) { // commenced, incomplete buffer
-
-			// complete the buffer:
-			remainingLength = BLOCK_LENGTH_BYTES - bufferPos;
-			if (remainingLength < len) { // full buffer + at least 1 byte
-				System.arraycopy(message, offset, buffer, bufferPos,
-						remainingLength);
-				t0 += BLOCK_LENGTH_BYTES;
-				if (t0 == 0) { // if message > 2^32
-					t1++;
-				}
-				compress(buffer, 0);
-				bufferPos = 0;
-				Arrays.fill(buffer, (byte) 0);// clear buffer
-			} else {
-				System.arraycopy(message, offset, buffer, bufferPos, len);
-				bufferPos += len;
-				return;
-			}
-		}
-
-		// process blocks except last block (also if last block is full)
-		int messagePos;
-		int blockWiseLastPos = offset + len - BLOCK_LENGTH_BYTES;
-		for (messagePos = offset + remainingLength;
-				messagePos < blockWiseLastPos;
-				messagePos += BLOCK_LENGTH_BYTES) { // block wise 64 bytes
-			// without buffer:
-			t0 += BLOCK_LENGTH_BYTES;
-			if (t0 == 0) {
-				t1++;
-			}
-			compress(message, messagePos);
-		}
-
-		// fill the buffer with left bytes, this might be a full block
-		System.arraycopy(message, messagePos, buffer, 0, offset + len
-				- messagePos);
-		bufferPos += offset + len - messagePos;
-	}
-
-	/**
-	 * Close the digest, producing the final digest value. The doFinal() call
-	 * leaves the digest reset. Key, salt and personal string remain.
-	 *
-	 * @param out the array the digest is to be copied into.
-	 * @param outOffset the offset into the out array the digest is to start at.
-	 */
-	public int doFinal(byte[] out, int outOffset) {
-		f0 = 0xFFFFFFFF;
-		t0 += bufferPos;
-		// bufferPos may be < 64, so (t0 == 0) does not work
-		// for 2^32 < message length > 2^32 - 63
-		if ((t0 < 0) && (bufferPos > -t0)) {
-			t1++;
-		}
-		compress(buffer, 0);
-		Arrays.fill(buffer, (byte) 0);// Holds eventually the key if input is null
-		Arrays.fill(internalState, 0);
-
-		for (int i = 0; i < chainValue.length && (i * 4 < digestLength); i++) {
-			byte[] bytes = int2bytes(chainValue[i]);
-
-			if (i * 4 < digestLength - 4) {
-				System.arraycopy(bytes, 0, out, outOffset + i * 4, 4);
-			} else {
-				System.arraycopy(bytes, 0, out, outOffset + i * 4,
-						digestLength - (i * 4));
-			}
-		}
-
-		Arrays.fill(chainValue, 0);
-
-		reset();
-
-		return digestLength;
-	}
-
-	/**
-	 * Reset the digest back to its initial state. The key, the salt and the
-	 * personal string will remain for further computations.
-	 */
-	public void reset() {
-		bufferPos = 0;
-		f0 = 0;
-		t0 = 0;
-		t1 = 0;
-		chainValue = null;
-		if (key != null) {
-			Arrays.fill(buffer, (byte) 0);
-			System.arraycopy(key, 0, buffer, 0, key.length);
-			bufferPos = BLOCK_LENGTH_BYTES; // zero padding
-		}
-		init();
-	}
-
-	private void compress(byte[] message, int messagePos) {
-		initializeInternalState();
-
-		int[] m = new int[16];
-		for (int j = 0; j < 16; j++) {
-			m[j] = bytes2int(message, messagePos + j * 4);
-		}
-
-		for (int round = 0; round < ROUNDS; round++) {
-
-			// G apply to columns of internalState:m[blake2s_sigma[round][2 *
-			// blockPos]] /+1
-			G(m[blake2s_sigma[round][0]], m[blake2s_sigma[round][1]], 0, 4, 8,
-					12);
-			G(m[blake2s_sigma[round][2]], m[blake2s_sigma[round][3]], 1, 5, 9,
-					13);
-			G(m[blake2s_sigma[round][4]], m[blake2s_sigma[round][5]], 2, 6, 10,
-					14);
-			G(m[blake2s_sigma[round][6]], m[blake2s_sigma[round][7]], 3, 7, 11,
-					15);
-			// G apply to diagonals of internalState:
-			G(m[blake2s_sigma[round][8]], m[blake2s_sigma[round][9]], 0, 5, 10,
-					15);
-			G(m[blake2s_sigma[round][10]], m[blake2s_sigma[round][11]], 1, 6,
-					11, 12);
-			G(m[blake2s_sigma[round][12]], m[blake2s_sigma[round][13]], 2, 7,
-					8, 13);
-			G(m[blake2s_sigma[round][14]], m[blake2s_sigma[round][15]], 3, 4,
-					9, 14);
-		}
-
-		// update chain values:
-		for (int offset = 0; offset < chainValue.length; offset++) {
-			chainValue[offset] = chainValue[offset] ^ internalState[offset]
-					^ internalState[offset + 8];
-		}
-	}
-
-	private void G(int m1, int m2, int posA, int posB, int posC, int posD) {
-		internalState[posA] = internalState[posA] + internalState[posB] + m1;
-		internalState[posD] = rotr32(internalState[posD] ^ internalState[posA],
-				16);
-		internalState[posC] = internalState[posC] + internalState[posD];
-		internalState[posB] = rotr32(internalState[posB] ^ internalState[posC],
-				12);
-		internalState[posA] = internalState[posA] + internalState[posB] + m2;
-		internalState[posD] = rotr32(internalState[posD] ^ internalState[posA],
-				8);
-		internalState[posC] = internalState[posC] + internalState[posD];
-		internalState[posB] = rotr32(internalState[posB] ^ internalState[posC],
-				7);
-	}
-
-	private int rotr32(int x, int rot) {
-		return x >>> rot | (x << (32 - rot));
-	}
-
-	// convert one int value in byte array
-	// little-endian byte order!
-	private byte[] int2bytes(int intValue) {
-		return new byte[] {
-				(byte) intValue, (byte) (intValue >> 8),
-				(byte) (intValue >> 16), (byte) (intValue >> 24)
-		};
-	}
-
-	// little-endian byte order!
-	private int bytes2int(byte[] byteArray, int offset) {
-		return (((int) byteArray[offset] & 0xFF)
-				| (((int) byteArray[offset + 1] & 0xFF) << 8)
-				| (((int) byteArray[offset + 2] & 0xFF) << 16)
-				| (((int) byteArray[offset + 3] & 0xFF) << 24));
-	}
-
-	/**
-	 * Return the algorithm name.
-	 *
-	 * @return the algorithm name
-	 */
-	public String getAlgorithmName() {
-		return "BLAKE2s";
-	}
-
-	/**
-	 * Return the size in bytes of the digest produced by this message digest.
-	 *
-	 * @return the size in bytes of the digest produced by this message digest.
-	 */
-	public int getDigestSize() {
-		return digestLength;
-	}
-
-	/**
-	 * Return the size in bytes of the internal buffer the digest applies its
-	 * compression function to.
-	 *
-	 * @return byte length of the digest's internal buffer.
-	 */
-	public int getByteLength() {
-		return BLOCK_LENGTH_BYTES;
-	}
-
-	/**
-	 * Overwrite the key if it is no longer used (zeroization).
-	 */
-	public void clearKey() {
-		if (key != null) {
-			Arrays.fill(key, (byte) 0);
-			Arrays.fill(buffer,  (byte) 0);
-		}
-	}
-
-	/**
-	 * Overwrite the salt (pepper) if it is secret and no longer used
-	 * (zeroization).
-	 */
-	public void clearSalt() {
-		if (salt != null) {
-			Arrays.fill(salt, (byte) 0);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java

@@ -1,107 +1,59 @@
 package org.briarproject.bramble.crypto;
 
+import net.i2p.crypto.eddsa.EdDSAPrivateKey;
+import net.i2p.crypto.eddsa.EdDSAPublicKey;
+import net.i2p.crypto.eddsa.KeyPairGenerator;
+
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
-import org.briarproject.bramble.api.transport.IncomingKeys;
-import org.briarproject.bramble.api.transport.OutgoingKeys;
-import org.briarproject.bramble.api.transport.TransportKeys;
 import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.util.StringUtils;
-import org.spongycastle.crypto.AsymmetricCipherKeyPair;
-import org.spongycastle.crypto.CipherParameters;
 import org.spongycastle.crypto.CryptoException;
 import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
-import org.spongycastle.crypto.digests.SHA256Digest;
-import org.spongycastle.crypto.generators.ECKeyPairGenerator;
-import org.spongycastle.crypto.generators.PKCS5S2ParametersGenerator;
-import org.spongycastle.crypto.params.ECKeyGenerationParameters;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
-import org.spongycastle.crypto.params.KeyParameter;
+import org.spongycastle.crypto.digests.Blake2bDigest;
+import org.whispersystems.curve25519.Curve25519;
+import org.whispersystems.curve25519.Curve25519KeyPair;
 
-import java.nio.charset.Charset;
 import java.security.GeneralSecurityException;
 import java.security.NoSuchAlgorithmException;
 import java.security.Provider;
 import java.security.SecureRandom;
 import java.security.Security;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
-import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
-import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENGTH;
-import static org.briarproject.bramble.crypto.EllipticCurveConstants.PARAMETERS;
-import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
-import static org.briarproject.bramble.util.ByteUtils.MAX_32_BIT_UNSIGNED;
 
+@NotNullByDefault
 class CryptoComponentImpl implements CryptoComponent {
 
 	private static final Logger LOG =
 			Logger.getLogger(CryptoComponentImpl.class.getName());
 
-	private static final int AGREEMENT_KEY_PAIR_BITS = 256;
 	private static final int SIGNATURE_KEY_PAIR_BITS = 256;
 	private static final int STORAGE_IV_BYTES = 24; // 196 bits
 	private static final int PBKDF_SALT_BYTES = 32; // 256 bits
-	private static final int PBKDF_TARGET_MILLIS = 500;
-	private static final int PBKDF_SAMPLES = 30;
-	private static final int HASH_SIZE = 256 / 8;
-
-	private static byte[] ascii(String s) {
-		return s.getBytes(Charset.forName("US-ASCII"));
-	}
-
-	// KDF labels for contact exchange stream header key derivation
-	private static final byte[] A_INVITE = ascii("ALICE_INVITATION_KEY");
-	private static final byte[] B_INVITE = ascii("BOB_INVITATION_KEY");
-	// KDF labels for contact exchange signature nonce derivation
-	private static final byte[] A_SIG_NONCE = ascii("ALICE_SIGNATURE_NONCE");
-	private static final byte[] B_SIG_NONCE = ascii("BOB_SIGNATURE_NONCE");
-	// Hash label for BQP public key commitment derivation
-	private static final String COMMIT =
-			"org.briarproject.bramble.COMMIT";
-	// Hash label for shared secret derivation
-	private static final String SHARED_SECRET =
-			"org.briarproject.bramble.SHARED_SECRET";
-	// KDF label for BQP confirmation key derivation
-	private static final byte[] CONFIRMATION_KEY = ascii("CONFIRMATION_KEY");
-	// KDF label for master key derivation
-	private static final byte[] MASTER_KEY = ascii("MASTER_KEY");
-	// KDF labels for tag key derivation
-	private static final byte[] A_TAG = ascii("ALICE_TAG_KEY");
-	private static final byte[] B_TAG = ascii("BOB_TAG_KEY");
-	// KDF labels for header key derivation
-	private static final byte[] A_HEADER = ascii("ALICE_HEADER_KEY");
-	private static final byte[] B_HEADER = ascii("BOB_HEADER_KEY");
-	// KDF labels for MAC key derivation
-	private static final byte[] A_MAC = ascii("ALICE_MAC_KEY");
-	private static final byte[] B_MAC = ascii("BOB_MAC_KEY");
-	// KDF label for key rotation
-	private static final byte[] ROTATE = ascii("ROTATE");
+	private static final int PBKDF_FORMAT_SCRYPT = 0;
 
 	private final SecureRandom secureRandom;
-	private final ECKeyPairGenerator agreementKeyPairGenerator;
-	private final ECKeyPairGenerator signatureKeyPairGenerator;
+	private final PasswordBasedKdf passwordBasedKdf;
+	private final Curve25519 curve25519;
+	private final KeyPairGenerator signatureKeyPairGenerator;
 	private final KeyParser agreementKeyParser, signatureKeyParser;
 	private final MessageEncrypter messageEncrypter;
 
 	@Inject
-	CryptoComponentImpl(SecureRandomProvider secureRandomProvider) {
+	CryptoComponentImpl(SecureRandomProvider secureRandomProvider,
+			PasswordBasedKdf passwordBasedKdf) {
 		if (LOG.isLoggable(INFO)) {
 			SecureRandom defaultSecureRandom = new SecureRandom();
 			String name = defaultSecureRandom.getProvider().getName();
@@ -121,16 +73,13 @@ class CryptoComponentImpl implements CryptoComponent {
 			}
 		}
 		secureRandom = new SecureRandom();
-		ECKeyGenerationParameters params = new ECKeyGenerationParameters(
-				PARAMETERS, secureRandom);
-		agreementKeyPairGenerator = new ECKeyPairGenerator();
-		agreementKeyPairGenerator.init(params);
-		signatureKeyPairGenerator = new ECKeyPairGenerator();
-		signatureKeyPairGenerator.init(params);
-		agreementKeyParser = new Sec1KeyParser(PARAMETERS,
-				AGREEMENT_KEY_PAIR_BITS);
-		signatureKeyParser = new Sec1KeyParser(PARAMETERS,
-				SIGNATURE_KEY_PAIR_BITS);
+		this.passwordBasedKdf = passwordBasedKdf;
+		curve25519 = Curve25519.getInstance("java");
+		signatureKeyPairGenerator = new KeyPairGenerator();
+		signatureKeyPairGenerator.initialize(SIGNATURE_KEY_PAIR_BITS,
+				secureRandom);
+		agreementKeyParser = new Curve25519KeyParser();
+		signatureKeyParser = new EdKeyParser();
 		messageEncrypter = new MessageEncrypter(secureRandom);
 	}
 
@@ -174,16 +123,17 @@ class CryptoComponentImpl implements CryptoComponent {
 	// Package access for testing
 	byte[] performRawKeyAgreement(PrivateKey priv, PublicKey pub)
 			throws GeneralSecurityException {
-		if (!(priv instanceof Sec1PrivateKey))
+		if (!(priv instanceof Curve25519PrivateKey))
 			throw new IllegalArgumentException();
-		if (!(pub instanceof Sec1PublicKey))
+		if (!(pub instanceof Curve25519PublicKey))
 			throw new IllegalArgumentException();
-		ECPrivateKeyParameters ecPriv = ((Sec1PrivateKey) priv).getKey();
-		ECPublicKeyParameters ecPub = ((Sec1PublicKey) pub).getKey();
 		long now = System.currentTimeMillis();
-		ECDHCBasicAgreement agreement = new ECDHCBasicAgreement();
-		agreement.init(ecPriv);
-		byte[] secret = agreement.calculateAgreement(ecPub).toByteArray();
+		byte[] secret = curve25519.calculateAgreement(pub.getEncoded(),
+				priv.getEncoded());
+		// If the shared secret is all zeroes, the public key is invalid
+		byte allZero = 0;
+		for (byte b : secret) allZero |= b;
+		if (allZero == 0) throw new GeneralSecurityException();
 		long duration = System.currentTimeMillis() - now;
 		if (LOG.isLoggable(INFO))
 			LOG.info("Deriving shared secret took " + duration + " ms");
@@ -192,18 +142,10 @@ class CryptoComponentImpl implements CryptoComponent {
 
 	@Override
 	public KeyPair generateAgreementKeyPair() {
-		AsymmetricCipherKeyPair keyPair =
-				agreementKeyPairGenerator.generateKeyPair();
-		// Return a wrapper that uses the SEC 1 encoding
-		ECPublicKeyParameters ecPublicKey =
-				(ECPublicKeyParameters) keyPair.getPublic();
-		PublicKey publicKey = new Sec1PublicKey(ecPublicKey
-		);
-		ECPrivateKeyParameters ecPrivateKey =
-				(ECPrivateKeyParameters) keyPair.getPrivate();
-		PrivateKey privateKey = new Sec1PrivateKey(ecPrivateKey,
-				AGREEMENT_KEY_PAIR_BITS);
-		return new KeyPair(publicKey, privateKey);
+		Curve25519KeyPair keyPair = curve25519.generateKeyPair();
+		PublicKey pub = new Curve25519PublicKey(keyPair.getPublicKey());
+		PrivateKey priv = new Curve25519PrivateKey(keyPair.getPrivateKey());
+		return new KeyPair(pub, priv);
 	}
 
 	@Override
@@ -213,17 +155,12 @@ class CryptoComponentImpl implements CryptoComponent {
 
 	@Override
 	public KeyPair generateSignatureKeyPair() {
-		AsymmetricCipherKeyPair keyPair =
+		java.security.KeyPair keyPair =
 				signatureKeyPairGenerator.generateKeyPair();
-		// Return a wrapper that uses the SEC 1 encoding
-		ECPublicKeyParameters ecPublicKey =
-				(ECPublicKeyParameters) keyPair.getPublic();
-		PublicKey publicKey = new Sec1PublicKey(ecPublicKey
-		);
-		ECPrivateKeyParameters ecPrivateKey =
-				(ECPrivateKeyParameters) keyPair.getPrivate();
-		PrivateKey privateKey = new Sec1PrivateKey(ecPrivateKey,
-				SIGNATURE_KEY_PAIR_BITS);
+		EdDSAPublicKey edPublicKey = (EdDSAPublicKey) keyPair.getPublic();
+		PublicKey publicKey = new EdPublicKey(edPublicKey.getAbyte());
+		EdDSAPrivateKey edPrivateKey = (EdDSAPrivateKey) keyPair.getPrivate();
+		PrivateKey privateKey = new EdPrivateKey(edPrivateKey.getSeed());
 		return new KeyPair(publicKey, privateKey);
 	}
 
@@ -238,205 +175,47 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 
 	@Override
-	public SecretKey deriveHeaderKey(SecretKey master,
-			boolean alice) {
-		return new SecretKey(macKdf(master, alice ? A_INVITE : B_INVITE));
+	public SecretKey deriveKey(String label, SecretKey k, byte[]... inputs) {
+		byte[] mac = mac(label, k, inputs);
+		if (mac.length != SecretKey.LENGTH) throw new IllegalStateException();
+		return new SecretKey(mac);
 	}
 
 	@Override
-	public SecretKey deriveMacKey(SecretKey master, boolean alice) {
-		return new SecretKey(macKdf(master, alice ? A_MAC : B_MAC));
-	}
-
-	@Override
-	public byte[] deriveSignatureNonce(SecretKey master,
-			boolean alice) {
-		return macKdf(master, alice ? A_SIG_NONCE : B_SIG_NONCE);
-	}
-
-	@Override
-	public byte[] deriveKeyCommitment(byte[] publicKey) {
-		byte[] hash = hash(COMMIT, publicKey);
-		// The output is the first COMMIT_LENGTH bytes of the hash
-		byte[] commitment = new byte[COMMIT_LENGTH];
-		System.arraycopy(hash, 0, commitment, 0, COMMIT_LENGTH);
-		return commitment;
-	}
-
-	@Override
-	public SecretKey deriveSharedSecret(byte[] theirPublicKey,
-			KeyPair ourKeyPair, boolean alice) throws GeneralSecurityException {
+	public SecretKey deriveSharedSecret(String label, PublicKey theirPublicKey,
+			KeyPair ourKeyPair, byte[]... inputs)
+			throws GeneralSecurityException {
 		PrivateKey ourPriv = ourKeyPair.getPrivate();
-		PublicKey theirPub = agreementKeyParser.parsePublicKey(theirPublicKey);
-		byte[] raw = performRawKeyAgreement(ourPriv, theirPub);
-		byte[] alicePub, bobPub;
-		if (alice) {
-			alicePub = ourKeyPair.getPublic().getEncoded();
-			bobPub = theirPublicKey;
-		} else {
-			alicePub = theirPublicKey;
-			bobPub = ourKeyPair.getPublic().getEncoded();
-		}
-		return new SecretKey(hash(SHARED_SECRET, raw, alicePub, bobPub));
-	}
-
-	@Override
-	public byte[] deriveConfirmationRecord(SecretKey sharedSecret,
-			byte[] theirPayload, byte[] ourPayload, byte[] theirPublicKey,
-			KeyPair ourKeyPair, boolean alice, boolean aliceRecord) {
-		SecretKey ck = new SecretKey(macKdf(sharedSecret, CONFIRMATION_KEY));
-		byte[] alicePayload, alicePub, bobPayload, bobPub;
-		if (alice) {
-			alicePayload = ourPayload;
-			alicePub = ourKeyPair.getPublic().getEncoded();
-			bobPayload = theirPayload;
-			bobPub = theirPublicKey;
-		} else {
-			alicePayload = theirPayload;
-			alicePub = theirPublicKey;
-			bobPayload = ourPayload;
-			bobPub = ourKeyPair.getPublic().getEncoded();
-		}
-		if (aliceRecord)
-			return macKdf(ck, alicePayload, alicePub, bobPayload, bobPub);
-		else
-			return macKdf(ck, bobPayload, bobPub, alicePayload, alicePub);
-	}
-
-	@Override
-	public SecretKey deriveMasterSecret(SecretKey sharedSecret) {
-		return new SecretKey(macKdf(sharedSecret, MASTER_KEY));
-	}
-
-	@Override
-	public SecretKey deriveMasterSecret(byte[] theirPublicKey,
-			KeyPair ourKeyPair, boolean alice) throws GeneralSecurityException {
-		return deriveMasterSecret(deriveSharedSecret(
-				theirPublicKey, ourKeyPair, alice));
-	}
-
-	@Override
-	public TransportKeys deriveTransportKeys(TransportId t,
-			SecretKey master, long rotationPeriod, boolean alice) {
-		// Keys for the previous period are derived from the master secret
-		SecretKey inTagPrev = deriveTagKey(master, t, !alice);
-		SecretKey inHeaderPrev = deriveHeaderKey(master, t, !alice);
-		SecretKey outTagPrev = deriveTagKey(master, t, alice);
-		SecretKey outHeaderPrev = deriveHeaderKey(master, t, alice);
-		// Derive the keys for the current and next periods
-		SecretKey inTagCurr = rotateKey(inTagPrev, rotationPeriod);
-		SecretKey inHeaderCurr = rotateKey(inHeaderPrev, rotationPeriod);
-		SecretKey inTagNext = rotateKey(inTagCurr, rotationPeriod + 1);
-		SecretKey inHeaderNext = rotateKey(inHeaderCurr, rotationPeriod + 1);
-		SecretKey outTagCurr = rotateKey(outTagPrev, rotationPeriod);
-		SecretKey outHeaderCurr = rotateKey(outHeaderPrev, rotationPeriod);
-		// Initialise the reordering windows and stream counters
-		IncomingKeys inPrev = new IncomingKeys(inTagPrev, inHeaderPrev,
-				rotationPeriod - 1);
-		IncomingKeys inCurr = new IncomingKeys(inTagCurr, inHeaderCurr,
-				rotationPeriod);
-		IncomingKeys inNext = new IncomingKeys(inTagNext, inHeaderNext,
-				rotationPeriod + 1);
-		OutgoingKeys outCurr = new OutgoingKeys(outTagCurr, outHeaderCurr,
-				rotationPeriod);
-		// Collect and return the keys
-		return new TransportKeys(t, inPrev, inCurr, inNext, outCurr);
-	}
-
-	@Override
-	public TransportKeys rotateTransportKeys(TransportKeys k,
-			long rotationPeriod) {
-		if (k.getRotationPeriod() >= rotationPeriod) return k;
-		IncomingKeys inPrev = k.getPreviousIncomingKeys();
-		IncomingKeys inCurr = k.getCurrentIncomingKeys();
-		IncomingKeys inNext = k.getNextIncomingKeys();
-		OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
-		long startPeriod = outCurr.getRotationPeriod();
-		// Rotate the keys
-		for (long p = startPeriod + 1; p <= rotationPeriod; p++) {
-			inPrev = inCurr;
-			inCurr = inNext;
-			SecretKey inNextTag = rotateKey(inNext.getTagKey(), p + 1);
-			SecretKey inNextHeader = rotateKey(inNext.getHeaderKey(), p + 1);
-			inNext = new IncomingKeys(inNextTag, inNextHeader, p + 1);
-			SecretKey outCurrTag = rotateKey(outCurr.getTagKey(), p);
-			SecretKey outCurrHeader = rotateKey(outCurr.getHeaderKey(), p);
-			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p);
-		}
-		// Collect and return the keys
-		return new TransportKeys(k.getTransportId(), inPrev, inCurr, inNext,
-				outCurr);
-	}
-
-	private SecretKey rotateKey(SecretKey k, long rotationPeriod) {
-		byte[] period = new byte[INT_64_BYTES];
-		ByteUtils.writeUint64(rotationPeriod, period, 0);
-		return new SecretKey(macKdf(k, ROTATE, period));
-	}
-
-	private SecretKey deriveTagKey(SecretKey master, TransportId t,
-			boolean alice) {
-		byte[] id = StringUtils.toUtf8(t.getString());
-		return new SecretKey(macKdf(master, alice ? A_TAG : B_TAG, id));
-	}
-
-	private SecretKey deriveHeaderKey(SecretKey master, TransportId t,
-			boolean alice) {
-		byte[] id = StringUtils.toUtf8(t.getString());
-		return new SecretKey(macKdf(master, alice ? A_HEADER : B_HEADER, id));
-	}
-
-	@Override
-	public void encodeTag(byte[] tag, SecretKey tagKey, int protocolVersion,
-			long streamNumber) {
-		if (tag.length < TAG_LENGTH) throw new IllegalArgumentException();
-		if (protocolVersion < 0 || protocolVersion > MAX_16_BIT_UNSIGNED)
-			throw new IllegalArgumentException();
-		if (streamNumber < 0 || streamNumber > MAX_32_BIT_UNSIGNED)
-			throw new IllegalArgumentException();
-		// Initialise the PRF
-		Digest prf = new Blake2sDigest(tagKey.getBytes());
-		// The output of the PRF must be long enough to use as a tag
-		int macLength = prf.getDigestSize();
-		if (macLength < TAG_LENGTH) throw new IllegalStateException();
-		// The input is the protocol version as a 16-bit integer, followed by
-		// the stream number as a 64-bit integer
-		byte[] protocolVersionBytes = new byte[INT_16_BYTES];
-		ByteUtils.writeUint16(protocolVersion, protocolVersionBytes, 0);
-		prf.update(protocolVersionBytes, 0, protocolVersionBytes.length);
-		byte[] streamNumberBytes = new byte[INT_64_BYTES];
-		ByteUtils.writeUint64(streamNumber, streamNumberBytes, 0);
-		prf.update(streamNumberBytes, 0, streamNumberBytes.length);
-		byte[] mac = new byte[macLength];
-		prf.doFinal(mac, 0);
-		// The output is the first TAG_LENGTH bytes of the MAC
-		System.arraycopy(mac, 0, tag, 0, TAG_LENGTH);
+		byte[][] hashInputs = new byte[inputs.length + 1][];
+		hashInputs[0] = performRawKeyAgreement(ourPriv, theirPublicKey);
+		System.arraycopy(inputs, 0, hashInputs, 1, inputs.length);
+		byte[] hash = hash(label, hashInputs);
+		if (hash.length != SecretKey.LENGTH) throw new IllegalStateException();
+		return new SecretKey(hash);
 	}
 
 	@Override
 	public byte[] sign(String label, byte[] toSign, byte[] privateKey)
 			throws GeneralSecurityException {
-		Signature signature = new SignatureImpl(secureRandom);
-		KeyParser keyParser = getSignatureKeyParser();
-		PrivateKey key = keyParser.parsePrivateKey(privateKey);
-		signature.initSign(key);
-		updateSignature(signature, label, toSign);
-		return signature.sign();
+		PrivateKey key = signatureKeyParser.parsePrivateKey(privateKey);
+		Signature sig = new EdSignature();
+		sig.initSign(key);
+		updateSignature(sig, label, toSign);
+		return sig.sign();
 	}
 
 	@Override
 	public boolean verify(String label, byte[] signedData, byte[] publicKey,
 			byte[] signature) throws GeneralSecurityException {
-		Signature sig = new SignatureImpl(secureRandom);
-		KeyParser keyParser = getSignatureKeyParser();
-		PublicKey key = keyParser.parsePublicKey(publicKey);
+		PublicKey key = signatureKeyParser.parsePublicKey(publicKey);
+		Signature sig = new EdSignature();
 		sig.initVerify(key);
 		updateSignature(sig, label, signedData);
 		return sig.verify(signature);
 	}
 
 	private void updateSignature(Signature signature, String label,
-			byte[] toSign) {
+			byte[] toSign) throws GeneralSecurityException {
 		byte[] labelBytes = StringUtils.toUtf8(label);
 		byte[] length = new byte[INT_32_BYTES];
 		ByteUtils.writeUint32(labelBytes.length, length, 0);
@@ -450,7 +229,7 @@ class CryptoComponentImpl implements CryptoComponent {
 	@Override
 	public byte[] hash(String label, byte[]... inputs) {
 		byte[] labelBytes = StringUtils.toUtf8(label);
-		Digest digest = new Blake2sDigest();
+		Digest digest = new Blake2bDigest(256);
 		byte[] length = new byte[INT_32_BYTES];
 		ByteUtils.writeUint32(labelBytes.length, length, 0);
 		digest.update(length, 0, length.length);
@@ -466,14 +245,13 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 
 	@Override
-	public int getHashLength() {
-		return HASH_SIZE;
-	}
-
-	@Override
-	public byte[] mac(SecretKey macKey, byte[]... inputs) {
-		Digest mac = new Blake2sDigest(macKey.getBytes());
+	public byte[] mac(String label, SecretKey macKey, byte[]... inputs) {
+		byte[] labelBytes = StringUtils.toUtf8(label);
+		Digest mac = new Blake2bDigest(macKey.getBytes(), 32, null, null);
 		byte[] length = new byte[INT_32_BYTES];
+		ByteUtils.writeUint32(labelBytes.length, length, 0);
+		mac.update(length, 0, length.length);
+		mac.update(labelBytes, 0, labelBytes.length);
 		for (byte[] input : inputs) {
 			ByteUtils.writeUint32(input.length, length, 0);
 			mac.update(length, 0, length.length);
@@ -492,23 +270,33 @@ class CryptoComponentImpl implements CryptoComponent {
 		byte[] salt = new byte[PBKDF_SALT_BYTES];
 		secureRandom.nextBytes(salt);
 		// Calibrate the KDF
-		int iterations = chooseIterationCount(PBKDF_TARGET_MILLIS);
+		int cost = passwordBasedKdf.chooseCostParameter();
 		// Derive the key from the password
-		SecretKey key = new SecretKey(pbkdf2(password, salt, iterations));
+		SecretKey key = passwordBasedKdf.deriveKey(password, salt, cost);
 		// Generate a random IV
 		byte[] iv = new byte[STORAGE_IV_BYTES];
 		secureRandom.nextBytes(iv);
-		// The output contains the salt, iterations, IV, ciphertext and MAC
-		int outputLen = salt.length + INT_32_BYTES + iv.length + input.length
-				+ macBytes;
+		// The output contains the format version, salt, cost parameter, IV,
+		// ciphertext and MAC
+		int outputLen = 1 + salt.length + INT_32_BYTES + iv.length
+				+ input.length + macBytes;
 		byte[] output = new byte[outputLen];
-		System.arraycopy(salt, 0, output, 0, salt.length);
-		ByteUtils.writeUint32(iterations, output, salt.length);
-		System.arraycopy(iv, 0, output, salt.length + INT_32_BYTES, iv.length);
+		int outputOff = 0;
+		// Format version
+		output[outputOff] = PBKDF_FORMAT_SCRYPT;
+		outputOff++;
+		// Salt
+		System.arraycopy(salt, 0, output, outputOff, salt.length);
+		outputOff += salt.length;
+		// Cost parameter
+		ByteUtils.writeUint32(cost, output, outputOff);
+		outputOff += INT_32_BYTES;
+		// IV
+		System.arraycopy(iv, 0, output, outputOff, iv.length);
+		outputOff += iv.length;
 		// Initialise the cipher and encrypt the plaintext
 		try {
 			cipher.init(true, key, iv);
-			int outputOff = salt.length + INT_32_BYTES + iv.length;
 			cipher.process(input, 0, input.length, output, outputOff);
 			return output;
 		} catch (GeneralSecurityException e) {
@@ -517,22 +305,36 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 
 	@Override
+	@Nullable
 	public byte[] decryptWithPassword(byte[] input, String password) {
 		AuthenticatedCipher cipher = new XSalsa20Poly1305AuthenticatedCipher();
 		int macBytes = cipher.getMacBytes();
-		// The input contains the salt, iterations, IV, ciphertext and MAC
-		if (input.length < PBKDF_SALT_BYTES + INT_32_BYTES + STORAGE_IV_BYTES
-				+ macBytes)
+		// The input contains the format version, salt, cost parameter, IV,
+		// ciphertext and MAC
+		if (input.length < 1 + PBKDF_SALT_BYTES + INT_32_BYTES
+				+ STORAGE_IV_BYTES + macBytes)
 			return null; // Invalid input
+		int inputOff = 0;
+		// Format version
+		byte formatVersion = input[inputOff];
+		inputOff++;
+		if (formatVersion != PBKDF_FORMAT_SCRYPT)
+			return null; // Unknown format
+		// Salt
 		byte[] salt = new byte[PBKDF_SALT_BYTES];
-		System.arraycopy(input, 0, salt, 0, salt.length);
-		long iterations = ByteUtils.readUint32(input, salt.length);
-		if (iterations < 0 || iterations > Integer.MAX_VALUE)
-			return null; // Invalid iteration count
+		System.arraycopy(input, inputOff, salt, 0, salt.length);
+		inputOff += salt.length;
+		// Cost parameter
+		long cost = ByteUtils.readUint32(input, inputOff);
+		inputOff += INT_32_BYTES;
+		if (cost < 2 || cost > Integer.MAX_VALUE)
+			return null; // Invalid cost parameter
+		// IV
 		byte[] iv = new byte[STORAGE_IV_BYTES];
-		System.arraycopy(input, salt.length + INT_32_BYTES, iv, 0, iv.length);
+		System.arraycopy(input, inputOff, iv, 0, iv.length);
+		inputOff += iv.length;
 		// Derive the key from the password
-		SecretKey key = new SecretKey(pbkdf2(password, salt, (int) iterations));
+		SecretKey key = passwordBasedKdf.deriveKey(password, salt, (int) cost);
 		// Initialise the cipher
 		try {
 			cipher.init(false, key, iv);
@@ -541,7 +343,6 @@ class CryptoComponentImpl implements CryptoComponent {
 		}
 		// Try to decrypt the ciphertext (may be invalid)
 		try {
-			int inputOff = salt.length + INT_32_BYTES + iv.length;
 			int inputLen = input.length - inputOff;
 			byte[] output = new byte[inputLen - macBytes];
 			cipher.process(input, inputOff, inputLen, output, 0);
@@ -564,88 +365,4 @@ class CryptoComponentImpl implements CryptoComponent {
 	public String asciiArmour(byte[] b, int lineLength) {
 		return AsciiArmour.wrap(b, lineLength);
 	}
-
-	// Key derivation function based on a pseudo-random function - see
-	// NIST SP 800-108, section 5.1
-	private byte[] macKdf(SecretKey key, byte[]... inputs) {
-		// Initialise the PRF
-		Digest prf = new Blake2sDigest(key.getBytes());
-		// The output of the PRF must be long enough to use as a key
-		int macLength = prf.getDigestSize();
-		if (macLength < SecretKey.LENGTH) throw new IllegalStateException();
-		// Calculate the PRF over the concatenated length-prefixed inputs
-		byte[] length = new byte[INT_32_BYTES];
-		for (byte[] input : inputs) {
-			ByteUtils.writeUint32(input.length, length, 0);
-			prf.update(length, 0, length.length);
-			prf.update(input, 0, input.length);
-		}
-		byte[] mac = new byte[macLength];
-		prf.doFinal(mac, 0);
-		// The output is the first SecretKey.LENGTH bytes of the MAC
-		if (mac.length == SecretKey.LENGTH) return mac;
-		byte[] truncated = new byte[SecretKey.LENGTH];
-		System.arraycopy(mac, 0, truncated, 0, truncated.length);
-		return truncated;
-	}
-
-	// Password-based key derivation function - see PKCS#5 v2.1, section 5.2
-	private byte[] pbkdf2(String password, byte[] salt, int iterations) {
-		byte[] utf8 = StringUtils.toUtf8(password);
-		Digest digest = new SHA256Digest();
-		PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(digest);
-		gen.init(utf8, salt, iterations);
-		int keyLengthInBits = SecretKey.LENGTH * 8;
-		CipherParameters p = gen.generateDerivedParameters(keyLengthInBits);
-		return ((KeyParameter) p).getKey();
-	}
-
-	// Package access for testing
-	int chooseIterationCount(int targetMillis) {
-		List<Long> quickSamples = new ArrayList<>(PBKDF_SAMPLES);
-		List<Long> slowSamples = new ArrayList<>(PBKDF_SAMPLES);
-		long iterationNanos = 0, initNanos = 0;
-		while (iterationNanos <= 0 || initNanos <= 0) {
-			// Sample the running time with one iteration and two iterations
-			for (int i = 0; i < PBKDF_SAMPLES; i++) {
-				quickSamples.add(sampleRunningTime(1));
-				slowSamples.add(sampleRunningTime(2));
-			}
-			// Calculate the iteration time and the initialisation time
-			long quickMedian = median(quickSamples);
-			long slowMedian = median(slowSamples);
-			iterationNanos = slowMedian - quickMedian;
-			initNanos = quickMedian - iterationNanos;
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Init: " + initNanos + ", iteration: "
-						+ iterationNanos);
-			}
-		}
-		long targetNanos = targetMillis * 1000L * 1000L;
-		long iterations = (targetNanos - initNanos) / iterationNanos;
-		if (LOG.isLoggable(INFO)) LOG.info("Target iterations: " + iterations);
-		if (iterations < 1) return 1;
-		if (iterations > Integer.MAX_VALUE) return Integer.MAX_VALUE;
-		return (int) iterations;
-	}
-
-	private long sampleRunningTime(int iterations) {
-		byte[] password = {'p', 'a', 's', 's', 'w', 'o', 'r', 'd'};
-		byte[] salt = new byte[PBKDF_SALT_BYTES];
-		int keyLengthInBits = SecretKey.LENGTH * 8;
-		long start = System.nanoTime();
-		Digest digest = new SHA256Digest();
-		PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(digest);
-		gen.init(password, salt, iterations);
-		gen.generateDerivedParameters(keyLengthInBits);
-		return System.nanoTime() - start;
-	}
-
-	private long median(List<Long> list) {
-		int size = list.size();
-		if (size == 0) throw new IllegalArgumentException();
-		Collections.sort(list);
-		if (size % 2 == 1) return list.get(size / 2);
-		return list.get(size / 2 - 1) + list.get(size / 2) / 2;
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoModule.java

@@ -3,9 +3,11 @@ package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.TimeLoggingExecutor;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
 import org.briarproject.bramble.api.crypto.StreamDecrypterFactory;
 import org.briarproject.bramble.api.crypto.StreamEncrypterFactory;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
 
@@ -65,8 +67,9 @@ public class CryptoModule {
 	@Provides
 	@Singleton
 	CryptoComponent provideCryptoComponent(
-			SecureRandomProvider secureRandomProvider) {
-		return new CryptoComponentImpl(secureRandomProvider);
+			SecureRandomProvider secureRandomProvider,
+			ScryptKdf passwordBasedKdf) {
+		return new CryptoComponentImpl(secureRandomProvider, passwordBasedKdf);
 	}
 
 	@Provides
@@ -74,6 +77,12 @@ public class CryptoModule {
 		return new PasswordStrengthEstimatorImpl();
 	}
 
+	@Provides
+	TransportCrypto provideTransportCrypto(
+			TransportCryptoImpl transportCrypto) {
+		return transportCrypto;
+	}
+
 	@Provides
 	StreamDecrypterFactory provideStreamDecrypterFactory(
 			Provider<AuthenticatedCipher> cipherProvider) {
@@ -81,9 +90,17 @@ public class CryptoModule {
 	}
 
 	@Provides
-	StreamEncrypterFactory provideStreamEncrypterFactory(CryptoComponent crypto,
+	StreamEncrypterFactory provideStreamEncrypterFactory(
+			CryptoComponent crypto, TransportCrypto transportCrypto,
 			Provider<AuthenticatedCipher> cipherProvider) {
-		return new StreamEncrypterFactoryImpl(crypto, cipherProvider);
+		return new StreamEncrypterFactoryImpl(crypto, transportCrypto,
+				cipherProvider);
+	}
+
+	@Provides
+	KeyAgreementCrypto provideKeyAgreementCrypto(
+			KeyAgreementCryptoImpl keyAgreementCrypto) {
+		return keyAgreementCrypto;
 	}
 
 	@Provides

bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519KeyParser.java

@@ -0,0 +1,35 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.KeyParser;
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.security.GeneralSecurityException;
+
+@NotNullByDefault
+class Curve25519KeyParser implements KeyParser {
+
+	@Override
+	public PublicKey parsePublicKey(byte[] encodedKey)
+			throws GeneralSecurityException {
+		if (encodedKey.length != 32) throw new GeneralSecurityException();
+		return new Curve25519PublicKey(encodedKey);
+	}
+
+	@Override
+	public PrivateKey parsePrivateKey(byte[] encodedKey)
+			throws GeneralSecurityException {
+		if (encodedKey.length != 32) throw new GeneralSecurityException();
+		return new Curve25519PrivateKey(clamp(encodedKey));
+	}
+
+	static byte[] clamp(byte[] b) {
+		byte[] clamped = new byte[32];
+		System.arraycopy(b, 0, clamped, 0, 32);
+		clamped[0] &= 248;
+		clamped[31] &= 127;
+		clamped[31] |= 64;
+		return clamped;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519PrivateKey.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+class Curve25519PrivateKey extends Bytes implements PrivateKey {
+
+	Curve25519PrivateKey(byte[] bytes) {
+		super(bytes);
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519PublicKey.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+class Curve25519PublicKey extends Bytes implements PublicKey {
+
+	Curve25519PublicKey(byte[] bytes) {
+		super(bytes);
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/EdKeyParser.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.KeyParser;
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.security.GeneralSecurityException;
+
+@NotNullByDefault
+class EdKeyParser implements KeyParser {
+
+	@Override
+	public PublicKey parsePublicKey(byte[] encodedKey)
+			throws GeneralSecurityException {
+		if (encodedKey.length != 32) throw new GeneralSecurityException();
+		return new EdPublicKey(encodedKey);
+	}
+
+	@Override
+	public PrivateKey parsePrivateKey(byte[] encodedKey)
+			throws GeneralSecurityException {
+		if (encodedKey.length != 32) throw new GeneralSecurityException();
+		return new EdPrivateKey(encodedKey);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/EdPrivateKey.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+class EdPrivateKey extends Bytes implements PrivateKey {
+
+	EdPrivateKey(byte[] bytes) {
+		super(bytes);
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/EdPublicKey.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+class EdPublicKey extends Bytes implements PublicKey {
+
+	EdPublicKey(byte[] bytes) {
+		super(bytes);
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/EdSignature.java

@@ -0,0 +1,83 @@
+package org.briarproject.bramble.crypto;
+
+import net.i2p.crypto.eddsa.EdDSAPrivateKey;
+import net.i2p.crypto.eddsa.EdDSAPublicKey;
+import net.i2p.crypto.eddsa.EdDSASecurityProvider;
+import net.i2p.crypto.eddsa.spec.EdDSANamedCurveSpec;
+import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable;
+import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec;
+import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec;
+
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.security.GeneralSecurityException;
+import java.security.NoSuchAlgorithmException;
+import java.security.Provider;
+
+import static net.i2p.crypto.eddsa.EdDSAEngine.SIGNATURE_ALGORITHM;
+
+@NotNullByDefault
+class EdSignature implements Signature {
+
+	private static final Provider PROVIDER = new EdDSASecurityProvider();
+
+	private static final EdDSANamedCurveSpec CURVE_SPEC =
+			EdDSANamedCurveTable.getByName("Ed25519");
+
+	private final java.security.Signature signature;
+
+	EdSignature() {
+		try {
+			signature = java.security.Signature
+					.getInstance(SIGNATURE_ALGORITHM, PROVIDER);
+		} catch (NoSuchAlgorithmException e) {
+			throw new AssertionError(e);
+		}
+	}
+
+	@Override
+	public void initSign(PrivateKey k) throws GeneralSecurityException {
+		if (!(k instanceof EdPrivateKey))
+			throw new IllegalArgumentException();
+		EdDSAPrivateKey privateKey = new EdDSAPrivateKey(
+				new EdDSAPrivateKeySpec(k.getEncoded(), CURVE_SPEC));
+		signature.initSign(privateKey);
+	}
+
+	@Override
+	public void initVerify(PublicKey k) throws GeneralSecurityException {
+		if (!(k instanceof EdPublicKey))
+			throw new IllegalArgumentException();
+		EdDSAPublicKey publicKey = new EdDSAPublicKey(
+				new EdDSAPublicKeySpec(k.getEncoded(), CURVE_SPEC));
+		signature.initVerify(publicKey);
+	}
+
+	@Override
+	public void update(byte b) throws GeneralSecurityException {
+		signature.update(b);
+	}
+
+	@Override
+	public void update(byte[] b) throws GeneralSecurityException {
+		signature.update(b);
+	}
+
+	@Override
+	public void update(byte[] b, int off, int len)
+			throws GeneralSecurityException {
+		signature.update(b, off, len);
+	}
+
+	@Override
+	public byte[] sign() throws GeneralSecurityException {
+		return signature.sign();
+	}
+
+	@Override
+	public boolean verify(byte[] sig) throws GeneralSecurityException {
+		return signature.verify(sig);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/EllipticCurveConstants.java

@@ -1,32 +0,0 @@
-package org.briarproject.bramble.crypto;
-
-import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
-import org.spongycastle.asn1.x9.X9ECParameters;
-import org.spongycastle.crypto.params.ECDomainParameters;
-import org.spongycastle.math.ec.ECCurve;
-import org.spongycastle.math.ec.ECMultiplier;
-import org.spongycastle.math.ec.ECPoint;
-import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
-
-import java.math.BigInteger;
-
-/**
- * Parameters for curve brainpoolp256r1 - see RFC 5639.
- */
-class EllipticCurveConstants {
-
-	static final ECDomainParameters PARAMETERS;
-
-	static {
-		// Start with the default implementation of the curve
-		X9ECParameters x9 = TeleTrusTNamedCurves.getByName("brainpoolp256r1");
-		// Use a constant-time multiplier
-		ECMultiplier monty = new MontgomeryLadderMultiplier();
-		ECCurve curve = x9.getCurve().configure().setMultiplier(monty).create();
-		BigInteger gX = x9.getG().getAffineXCoord().toBigInteger();
-		BigInteger gY = x9.getG().getAffineYCoord().toBigInteger();
-		ECPoint g = curve.createPoint(gX, gY);
-		// Convert to ECDomainParameters using the new multiplier
-		PARAMETERS = new ECDomainParameters(curve, g, x9.getN(), x9.getH());
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/crypto/KeyAgreementCryptoImpl.java

@@ -0,0 +1,56 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
+import org.briarproject.bramble.api.crypto.KeyPair;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.crypto.SecretKey;
+
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
+
+class KeyAgreementCryptoImpl implements KeyAgreementCrypto {
+
+	private final CryptoComponent crypto;
+
+	@Inject
+	KeyAgreementCryptoImpl(CryptoComponent crypto) {
+		this.crypto = crypto;
+	}
+
+	@Override
+	public byte[] deriveKeyCommitment(PublicKey publicKey) {
+		byte[] hash = crypto.hash(COMMIT_LABEL, publicKey.getEncoded());
+		// The output is the first COMMIT_LENGTH bytes of the hash
+		byte[] commitment = new byte[COMMIT_LENGTH];
+		System.arraycopy(hash, 0, commitment, 0, COMMIT_LENGTH);
+		return commitment;
+	}
+
+	@Override
+	public byte[] deriveConfirmationRecord(SecretKey sharedSecret,
+			byte[] theirPayload, byte[] ourPayload, PublicKey theirPublicKey,
+			KeyPair ourKeyPair, boolean alice, boolean aliceRecord) {
+		SecretKey ck = crypto.deriveKey(CONFIRMATION_KEY_LABEL, sharedSecret);
+		byte[] alicePayload, alicePub, bobPayload, bobPub;
+		if (alice) {
+			alicePayload = ourPayload;
+			alicePub = ourKeyPair.getPublic().getEncoded();
+			bobPayload = theirPayload;
+			bobPub = theirPublicKey.getEncoded();
+		} else {
+			alicePayload = theirPayload;
+			alicePub = theirPublicKey.getEncoded();
+			bobPayload = ourPayload;
+			bobPub = ourKeyPair.getPublic().getEncoded();
+		}
+		if (aliceRecord) {
+			return crypto.mac(CONFIRMATION_MAC_LABEL, ck, alicePayload,
+					alicePub, bobPayload, bobPub);
+		} else {
+			return crypto.mac(CONFIRMATION_MAC_LABEL, ck, bobPayload, bobPub,
+					alicePayload, alicePub);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/PasswordBasedKdf.java

@@ -0,0 +1,10 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+
+interface PasswordBasedKdf {
+
+	int chooseCostParameter();
+
+	SecretKey deriveKey(String password, byte[] salt, int cost);
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/ScryptKdf.java

@@ -0,0 +1,62 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.StringUtils;
+import org.spongycastle.crypto.generators.SCrypt;
+
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.logging.Level.INFO;
+
+class ScryptKdf implements PasswordBasedKdf {
+
+	private static final Logger LOG =
+			Logger.getLogger(ScryptKdf.class.getName());
+
+	private static final int MIN_COST = 256; // Min parameter N
+	private static final int MAX_COST = 1024 * 1024; // Max parameter N
+	private static final int BLOCK_SIZE = 8; // Parameter r
+	private static final int PARALLELIZATION = 1; // Parameter p
+	private static final int TARGET_MS = 1000;
+
+	private final Clock clock;
+
+	@Inject
+	ScryptKdf(Clock clock) {
+		this.clock = clock;
+	}
+
+	@Override
+	public int chooseCostParameter() {
+		// Increase the cost from min to max while measuring performance
+		int cost = MIN_COST;
+		while (cost * 2 <= MAX_COST && measureDuration(cost) * 2 <= TARGET_MS)
+			cost *= 2;
+		if (LOG.isLoggable(INFO))
+			LOG.info("KDF cost parameter " + cost);
+		return cost;
+	}
+
+	private long measureDuration(int cost) {
+		byte[] password = new byte[16], salt = new byte[32];
+		long start = clock.currentTimeMillis();
+		SCrypt.generate(password, salt, cost, BLOCK_SIZE, PARALLELIZATION,
+				SecretKey.LENGTH);
+		return clock.currentTimeMillis() - start;
+	}
+
+	@Override
+	public SecretKey deriveKey(String password, byte[] salt, int cost) {
+		long start = System.currentTimeMillis();
+		byte[] passwordBytes = StringUtils.toUtf8(password);
+		SecretKey k = new SecretKey(SCrypt.generate(passwordBytes, salt, cost,
+				BLOCK_SIZE, PARALLELIZATION, SecretKey.LENGTH));
+		long duration = System.currentTimeMillis() - start;
+		if (LOG.isLoggable(INFO))
+			LOG.info("Deriving key from password took " + duration + " ms");
+		return k;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/crypto/Signature.java

@@ -22,25 +22,25 @@ interface Signature {
 	/**
 	 * @see {@link java.security.Signature#update(byte)}
 	 */
-	void update(byte b);
+	void update(byte b) throws GeneralSecurityException;
 
 	/**
 	 * @see {@link java.security.Signature#update(byte[])}
 	 */
-	void update(byte[] b);
+	void update(byte[] b) throws GeneralSecurityException;
 
 	/**
 	 * @see {@link java.security.Signature#update(byte[], int, int)}
 	 */
-	void update(byte[] b, int off, int len);
+	void update(byte[] b, int off, int len) throws GeneralSecurityException;
 
 	/**
 	 * @see {@link java.security.Signature#sign()}
 	 */
-	byte[] sign();
+	byte[] sign() throws GeneralSecurityException;
 
 	/**
 	 * @see {@link java.security.Signature#verify(byte[])}
 	 */
-	boolean verify(byte[] signature);
+	boolean verify(byte[] signature) throws GeneralSecurityException;
 }

bramble-core/src/main/java/org/briarproject/bramble/crypto/SignatureImpl.java

@@ -1,90 +0,0 @@
-package org.briarproject.bramble.crypto;
-
-import org.briarproject.bramble.api.crypto.PrivateKey;
-import org.briarproject.bramble.api.crypto.PublicKey;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
-import org.spongycastle.crypto.params.ParametersWithRandom;
-import org.spongycastle.crypto.signers.DSADigestSigner;
-import org.spongycastle.crypto.signers.DSAKCalculator;
-import org.spongycastle.crypto.signers.ECDSASigner;
-import org.spongycastle.crypto.signers.HMacDSAKCalculator;
-
-import java.security.GeneralSecurityException;
-import java.security.SecureRandom;
-import java.util.logging.Logger;
-
-import javax.annotation.concurrent.NotThreadSafe;
-
-import static java.util.logging.Level.INFO;
-
-@NotThreadSafe
-@NotNullByDefault
-class SignatureImpl implements Signature {
-
-	private static final Logger LOG =
-			Logger.getLogger(SignatureImpl.class.getName());
-
-	private final SecureRandom secureRandom;
-	private final DSADigestSigner signer;
-
-	SignatureImpl(SecureRandom secureRandom) {
-		this.secureRandom = secureRandom;
-		Digest digest = new Blake2sDigest();
-		DSAKCalculator calculator = new HMacDSAKCalculator(digest);
-		signer = new DSADigestSigner(new ECDSASigner(calculator), digest);
-	}
-
-	@Override
-	public void initSign(PrivateKey k) throws GeneralSecurityException {
-		if (!(k instanceof Sec1PrivateKey))
-			throw new IllegalArgumentException();
-		ECPrivateKeyParameters priv = ((Sec1PrivateKey) k).getKey();
-		signer.init(true, new ParametersWithRandom(priv, secureRandom));
-	}
-
-	@Override
-	public void initVerify(PublicKey k) throws GeneralSecurityException {
-		if (!(k instanceof Sec1PublicKey))
-			throw new IllegalArgumentException();
-		ECPublicKeyParameters pub = ((Sec1PublicKey) k).getKey();
-		signer.init(false, pub);
-	}
-
-	@Override
-	public void update(byte b) {
-		signer.update(b);
-	}
-
-	@Override
-	public void update(byte[] b) {
-		update(b, 0, b.length);
-	}
-
-	@Override
-	public void update(byte[] b, int off, int len) {
-		signer.update(b, off, len);
-	}
-
-	@Override
-	public byte[] sign() {
-		long now = System.currentTimeMillis();
-		byte[] signature = signer.generateSignature();
-		long duration = System.currentTimeMillis() - now;
-		if (LOG.isLoggable(INFO))
-			LOG.info("Generating signature took " + duration + " ms");
-		return signature;
-	}
-
-	@Override
-	public boolean verify(byte[] signature) {
-		long now = System.currentTimeMillis();
-		boolean valid = signer.verifySignature(signature);
-		long duration = System.currentTimeMillis() - now;
-		if (LOG.isLoggable(INFO))
-			LOG.info("Verifying signature took " + duration + " ms");
-		return valid;
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/crypto/StreamEncrypterFactoryImpl.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;
 import org.briarproject.bramble.api.crypto.StreamEncrypterFactory;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.transport.StreamContext;
 
@@ -22,12 +23,15 @@ import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENG
 class StreamEncrypterFactoryImpl implements StreamEncrypterFactory {
 
 	private final CryptoComponent crypto;
+	private final TransportCrypto transportCrypto;
 	private final Provider<AuthenticatedCipher> cipherProvider;
 
 	@Inject
 	StreamEncrypterFactoryImpl(CryptoComponent crypto,
+			TransportCrypto transportCrypto,
 			Provider<AuthenticatedCipher> cipherProvider) {
 		this.crypto = crypto;
+		this.transportCrypto = transportCrypto;
 		this.cipherProvider = cipherProvider;
 	}
 
@@ -37,7 +41,8 @@ class StreamEncrypterFactoryImpl implements StreamEncrypterFactory {
 		AuthenticatedCipher cipher = cipherProvider.get();
 		long streamNumber = ctx.getStreamNumber();
 		byte[] tag = new byte[TAG_LENGTH];
-		crypto.encodeTag(tag, ctx.getTagKey(), PROTOCOL_VERSION, streamNumber);
+		transportCrypto.encodeTag(tag, ctx.getTagKey(), PROTOCOL_VERSION,
+				streamNumber);
 		byte[] streamHeaderNonce = new byte[STREAM_HEADER_NONCE_LENGTH];
 		crypto.getSecureRandom().nextBytes(streamHeaderNonce);
 		SecretKey frameKey = crypto.generateSecretKey();

bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java

@@ -0,0 +1,136 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.transport.IncomingKeys;
+import org.briarproject.bramble.api.transport.OutgoingKeys;
+import org.briarproject.bramble.api.transport.TransportKeys;
+import org.briarproject.bramble.util.ByteUtils;
+import org.briarproject.bramble.util.StringUtils;
+import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.digests.Blake2bDigest;
+
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.api.transport.TransportConstants.ALICE_HEADER_LABEL;
+import static org.briarproject.bramble.api.transport.TransportConstants.ALICE_TAG_LABEL;
+import static org.briarproject.bramble.api.transport.TransportConstants.BOB_HEADER_LABEL;
+import static org.briarproject.bramble.api.transport.TransportConstants.BOB_TAG_LABEL;
+import static org.briarproject.bramble.api.transport.TransportConstants.ROTATE_LABEL;
+import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENGTH;
+import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
+import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
+import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
+import static org.briarproject.bramble.util.ByteUtils.MAX_32_BIT_UNSIGNED;
+
+class TransportCryptoImpl implements TransportCrypto {
+
+	private final CryptoComponent crypto;
+
+	@Inject
+	TransportCryptoImpl(CryptoComponent crypto) {
+		this.crypto = crypto;
+	}
+
+	@Override
+	public TransportKeys deriveTransportKeys(TransportId t,
+			SecretKey master, long rotationPeriod, boolean alice) {
+		// Keys for the previous period are derived from the master secret
+		SecretKey inTagPrev = deriveTagKey(master, t, !alice);
+		SecretKey inHeaderPrev = deriveHeaderKey(master, t, !alice);
+		SecretKey outTagPrev = deriveTagKey(master, t, alice);
+		SecretKey outHeaderPrev = deriveHeaderKey(master, t, alice);
+		// Derive the keys for the current and next periods
+		SecretKey inTagCurr = rotateKey(inTagPrev, rotationPeriod);
+		SecretKey inHeaderCurr = rotateKey(inHeaderPrev, rotationPeriod);
+		SecretKey inTagNext = rotateKey(inTagCurr, rotationPeriod + 1);
+		SecretKey inHeaderNext = rotateKey(inHeaderCurr, rotationPeriod + 1);
+		SecretKey outTagCurr = rotateKey(outTagPrev, rotationPeriod);
+		SecretKey outHeaderCurr = rotateKey(outHeaderPrev, rotationPeriod);
+		// Initialise the reordering windows and stream counters
+		IncomingKeys inPrev = new IncomingKeys(inTagPrev, inHeaderPrev,
+				rotationPeriod - 1);
+		IncomingKeys inCurr = new IncomingKeys(inTagCurr, inHeaderCurr,
+				rotationPeriod);
+		IncomingKeys inNext = new IncomingKeys(inTagNext, inHeaderNext,
+				rotationPeriod + 1);
+		OutgoingKeys outCurr = new OutgoingKeys(outTagCurr, outHeaderCurr,
+				rotationPeriod);
+		// Collect and return the keys
+		return new TransportKeys(t, inPrev, inCurr, inNext, outCurr);
+	}
+
+	@Override
+	public TransportKeys rotateTransportKeys(TransportKeys k,
+			long rotationPeriod) {
+		if (k.getRotationPeriod() >= rotationPeriod) return k;
+		IncomingKeys inPrev = k.getPreviousIncomingKeys();
+		IncomingKeys inCurr = k.getCurrentIncomingKeys();
+		IncomingKeys inNext = k.getNextIncomingKeys();
+		OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
+		long startPeriod = outCurr.getRotationPeriod();
+		// Rotate the keys
+		for (long p = startPeriod + 1; p <= rotationPeriod; p++) {
+			inPrev = inCurr;
+			inCurr = inNext;
+			SecretKey inNextTag = rotateKey(inNext.getTagKey(), p + 1);
+			SecretKey inNextHeader = rotateKey(inNext.getHeaderKey(), p + 1);
+			inNext = new IncomingKeys(inNextTag, inNextHeader, p + 1);
+			SecretKey outCurrTag = rotateKey(outCurr.getTagKey(), p);
+			SecretKey outCurrHeader = rotateKey(outCurr.getHeaderKey(), p);
+			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p);
+		}
+		// Collect and return the keys
+		return new TransportKeys(k.getTransportId(), inPrev, inCurr, inNext,
+				outCurr);
+	}
+
+	private SecretKey rotateKey(SecretKey k, long rotationPeriod) {
+		byte[] period = new byte[INT_64_BYTES];
+		ByteUtils.writeUint64(rotationPeriod, period, 0);
+		return crypto.deriveKey(ROTATE_LABEL, k, period);
+	}
+
+	private SecretKey deriveTagKey(SecretKey master, TransportId t,
+			boolean alice) {
+		String label = alice ? ALICE_TAG_LABEL : BOB_TAG_LABEL;
+		byte[] id = StringUtils.toUtf8(t.getString());
+		return crypto.deriveKey(label, master, id);
+	}
+
+	private SecretKey deriveHeaderKey(SecretKey master, TransportId t,
+			boolean alice) {
+		String label = alice ? ALICE_HEADER_LABEL : BOB_HEADER_LABEL;
+		byte[] id = StringUtils.toUtf8(t.getString());
+		return crypto.deriveKey(label, master, id);
+	}
+
+	@Override
+	public void encodeTag(byte[] tag, SecretKey tagKey, int protocolVersion,
+			long streamNumber) {
+		if (tag.length < TAG_LENGTH) throw new IllegalArgumentException();
+		if (protocolVersion < 0 || protocolVersion > MAX_16_BIT_UNSIGNED)
+			throw new IllegalArgumentException();
+		if (streamNumber < 0 || streamNumber > MAX_32_BIT_UNSIGNED)
+			throw new IllegalArgumentException();
+		// Initialise the PRF
+		Digest prf = new Blake2bDigest(tagKey.getBytes(), 32, null, null);
+		// The output of the PRF must be long enough to use as a tag
+		int macLength = prf.getDigestSize();
+		if (macLength < TAG_LENGTH) throw new IllegalStateException();
+		// The input is the protocol version as a 16-bit integer, followed by
+		// the stream number as a 64-bit integer
+		byte[] protocolVersionBytes = new byte[INT_16_BYTES];
+		ByteUtils.writeUint16(protocolVersion, protocolVersionBytes, 0);
+		prf.update(protocolVersionBytes, 0, protocolVersionBytes.length);
+		byte[] streamNumberBytes = new byte[INT_64_BYTES];
+		ByteUtils.writeUint64(streamNumber, streamNumberBytes, 0);
+		prf.update(streamNumberBytes, 0, streamNumberBytes.length);
+		byte[] mac = new byte[macLength];
+		prf.doFinal(mac, 0);
+		// The output is the first TAG_LENGTH bytes of the MAC
+		System.arraycopy(mac, 0, tag, 0, TAG_LENGTH);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/H2Database.java

@@ -24,21 +24,23 @@ import javax.inject.Inject;
 class H2Database extends JdbcDatabase {
 
 	private static final String HASH_TYPE = "BINARY(32)";
+	private static final String SECRET_TYPE = "BINARY(32)";
 	private static final String BINARY_TYPE = "BINARY";
 	private static final String COUNTER_TYPE = "INT NOT NULL AUTO_INCREMENT";
-	private static final String SECRET_TYPE = "BINARY(32)";
+	private static final String STRING_TYPE = "VARCHAR";
 
 	private final DatabaseConfig config;
 	private final String url;
 
 	@Inject
 	H2Database(DatabaseConfig config, Clock clock) {
-		super(HASH_TYPE, BINARY_TYPE, COUNTER_TYPE, SECRET_TYPE, clock);
+		super(HASH_TYPE, SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE,
+				clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();
 		url = "jdbc:h2:split:" + path + ";CIPHER=AES;MULTI_THREADED=1"
-				+ ";WRITE_DELAY=0;DB_CLOSE_ON_EXIT=false";
+				+ ";WRITE_DELAY=0";
 	}
 
 	@Override
@@ -93,6 +95,10 @@ class H2Database extends JdbcDatabase {
 		// Separate the file password from the user password with a space
 		String hex = StringUtils.toHexString(key.getBytes());
 		props.put("password", hex + " password");
-		return DriverManager.getConnection(url, props);
+		return DriverManager.getConnection(getUrl(), props);
+	}
+
+	String getUrl() {
+		return url;
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/HyperSqlDatabase.java

@@ -0,0 +1,101 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DatabaseConfig;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.MigrationListener;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.StringUtils;
+
+import java.io.File;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+/**
+ * Contains all the HSQLDB-specific code for the database.
+ */
+@NotNullByDefault
+class HyperSqlDatabase extends JdbcDatabase {
+
+	private static final String HASH_TYPE = "BINARY(32)";
+	private static final String SECRET_TYPE = "BINARY(32)";
+	private static final String BINARY_TYPE = "BINARY";
+	private static final String COUNTER_TYPE =
+			"INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY(START WITH 1)";
+	private static final String STRING_TYPE = "VARCHAR";
+
+	private final DatabaseConfig config;
+	private final String url;
+
+	@Inject
+	HyperSqlDatabase(DatabaseConfig config, Clock clock) {
+		super(HASH_TYPE, SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE,
+				clock);
+		this.config = config;
+		File dir = config.getDatabaseDirectory();
+		String path = new File(dir, "db").getAbsolutePath();
+		url = "jdbc:hsqldb:file:" + path
+				+ ";sql.enforce_size=false;allow_empty_batch=true"
+				+ ";encrypt_lobs=true;crypt_type=AES";
+	}
+
+	@Override
+	public boolean open(@Nullable MigrationListener listener) throws DbException {
+		boolean reopen = config.databaseExists();
+		if (!reopen) config.getDatabaseDirectory().mkdirs();
+		super.open("org.hsqldb.jdbc.JDBCDriver", reopen, listener);
+		return reopen;
+	}
+
+	@Override
+	public void close() throws DbException {
+		try {
+			super.closeAllConnections();
+			Connection c = createConnection();
+			Statement s = c.createStatement();
+			s.executeQuery("SHUTDOWN");
+			s.close();
+			c.close();
+		} catch (SQLException e) {
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public long getFreeSpace() throws DbException {
+		File dir = config.getDatabaseDirectory();
+		long maxSize = config.getMaxSize();
+		long free = dir.getFreeSpace();
+		long used = getDiskSpace(dir);
+		long quota = maxSize - used;
+		return Math.min(free, quota);
+	}
+
+	private long getDiskSpace(File f) {
+		if (f.isDirectory()) {
+			long total = 0;
+			File[] children = f.listFiles();
+			if (children != null)
+				for (File child : children) total += getDiskSpace(child);
+			return total;
+		} else if (f.isFile()) {
+			return f.length();
+		} else {
+			return 0;
+		}
+	}
+
+	@Override
+	protected Connection createConnection() throws SQLException {
+		SecretKey key = config.getEncryptionKey();
+		if (key == null) throw new IllegalStateException();
+		String hex = StringUtils.toHexString(key.getBytes());
+		return DriverManager.getConnection(url + ";crypt_key=" + hex);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -34,7 +34,6 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -73,31 +72,33 @@ import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 32;
+	static final int CODE_SCHEMA_VERSION = 35;
 
 	private static final String CREATE_SETTINGS =
 			"CREATE TABLE settings"
-					+ " (namespace VARCHAR NOT NULL,"
-					+ " key VARCHAR NOT NULL,"
-					+ " value VARCHAR NOT NULL,"
-					+ " PRIMARY KEY (namespace, key))";
+					+ " (namespace _STRING NOT NULL,"
+					+ " settingKey _STRING NOT NULL,"
+					+ " value _STRING NOT NULL,"
+					+ " PRIMARY KEY (namespace, settingKey))";
 
 	private static final String CREATE_LOCAL_AUTHORS =
 			"CREATE TABLE localAuthors"
-					+ " (authorId HASH NOT NULL,"
-					+ " name VARCHAR NOT NULL,"
-					+ " publicKey BINARY NOT NULL,"
-					+ " privateKey BINARY NOT NULL,"
+					+ " (authorId _HASH NOT NULL,"
+					+ " formatVersion INT NOT NULL,"
+					+ " name _STRING NOT NULL,"
+					+ " publicKey _BINARY NOT NULL,"
+					+ " privateKey _BINARY NOT NULL,"
 					+ " created BIGINT NOT NULL,"
 					+ " PRIMARY KEY (authorId))";
 
 	private static final String CREATE_CONTACTS =
 			"CREATE TABLE contacts"
-					+ " (contactId COUNTER,"
-					+ " authorId HASH NOT NULL,"
-					+ " name VARCHAR NOT NULL,"
-					+ " publicKey BINARY NOT NULL,"
-					+ " localAuthorId HASH NOT NULL,"
+					+ " (contactId _COUNTER,"
+					+ " authorId _HASH NOT NULL,"
+					+ " formatVersion INT NOT NULL,"
+					+ " name _STRING NOT NULL,"
+					+ " publicKey _BINARY NOT NULL,"
+					+ " localAuthorId _HASH NOT NULL,"
 					+ " verified BOOLEAN NOT NULL,"
 					+ " active BOOLEAN NOT NULL,"
 					+ " PRIMARY KEY (contactId),"
@@ -107,17 +108,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_GROUPS =
 			"CREATE TABLE groups"
-					+ " (groupId HASH NOT NULL,"
-					+ " clientId VARCHAR NOT NULL,"
-					+ " descriptor BINARY NOT NULL,"
+					+ " (groupId _HASH NOT NULL,"
+					+ " clientId _STRING NOT NULL,"
+					+ " descriptor _BINARY NOT NULL,"
 					+ " PRIMARY KEY (groupId))";
 
 	private static final String CREATE_GROUP_METADATA =
 			"CREATE TABLE groupMetadata"
-					+ " (groupId HASH NOT NULL,"
-					+ " key VARCHAR NOT NULL,"
-					+ " value BINARY NOT NULL,"
-					+ " PRIMARY KEY (groupId, key),"
+					+ " (groupId _HASH NOT NULL,"
+					+ " metaKey _STRING NOT NULL,"
+					+ " value _BINARY NOT NULL,"
+					+ " PRIMARY KEY (groupId, metaKey),"
 					+ " FOREIGN KEY (groupId)"
 					+ " REFERENCES groups (groupId)"
 					+ " ON DELETE CASCADE)";
@@ -125,7 +126,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final String CREATE_GROUP_VISIBILITIES =
 			"CREATE TABLE groupVisibilities"
 					+ " (contactId INT NOT NULL,"
-					+ " groupId HASH NOT NULL,"
+					+ " groupId _HASH NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
 					+ " PRIMARY KEY (contactId, groupId),"
 					+ " FOREIGN KEY (contactId)"
@@ -137,8 +138,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_MESSAGES =
 			"CREATE TABLE messages"
-					+ " (messageId HASH NOT NULL,"
-					+ " groupId HASH NOT NULL,"
+					+ " (messageId _HASH NOT NULL,"
+					+ " groupId _HASH NOT NULL,"
 					+ " timestamp BIGINT NOT NULL,"
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
@@ -151,12 +152,12 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_MESSAGE_METADATA =
 			"CREATE TABLE messageMetadata"
-					+ " (messageId HASH NOT NULL,"
-					+ " groupId HASH NOT NULL," // Denormalised
+					+ " (messageId _HASH NOT NULL,"
+					+ " groupId _HASH NOT NULL," // Denormalised
 					+ " state INT NOT NULL," // Denormalised
-					+ " key VARCHAR NOT NULL,"
-					+ " value BINARY NOT NULL,"
-					+ " PRIMARY KEY (messageId, key),"
+					+ " metaKey _STRING NOT NULL,"
+					+ " value _BINARY NOT NULL,"
+					+ " PRIMARY KEY (messageId, metaKey),"
 					+ " FOREIGN KEY (messageId)"
 					+ " REFERENCES messages (messageId)"
 					+ " ON DELETE CASCADE,"
@@ -166,9 +167,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_MESSAGE_DEPENDENCIES =
 			"CREATE TABLE messageDependencies"
-					+ " (groupId HASH NOT NULL,"
-					+ " messageId HASH NOT NULL,"
-					+ " dependencyId HASH NOT NULL," // Not a foreign key
+					+ " (groupId _HASH NOT NULL,"
+					+ " messageId _HASH NOT NULL,"
+					+ " dependencyId _HASH NOT NULL," // Not a foreign key
 					+ " FOREIGN KEY (groupId)"
 					+ " REFERENCES groups (groupId)"
 					+ " ON DELETE CASCADE,"
@@ -178,7 +179,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_OFFERS =
 			"CREATE TABLE offers"
-					+ " (messageId HASH NOT NULL," // Not a foreign key
+					+ " (messageId _HASH NOT NULL," // Not a foreign key
 					+ " contactId INT NOT NULL,"
 					+ " PRIMARY KEY (messageId, contactId),"
 					+ " FOREIGN KEY (contactId)"
@@ -187,9 +188,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_STATUSES =
 			"CREATE TABLE statuses"
-					+ " (messageId HASH NOT NULL,"
+					+ " (messageId _HASH NOT NULL,"
 					+ " contactId INT NOT NULL,"
-					+ " groupId HASH NOT NULL," // Denormalised
+					+ " groupId _HASH NOT NULL," // Denormalised
 					+ " timestamp BIGINT NOT NULL," // Denormalised
 					+ " length INT NOT NULL," // Denormalised
 					+ " state INT NOT NULL," // Denormalised
@@ -214,20 +215,20 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	private static final String CREATE_TRANSPORTS =
 			"CREATE TABLE transports"
-					+ " (transportId VARCHAR NOT NULL,"
+					+ " (transportId _STRING NOT NULL,"
 					+ " maxLatency INT NOT NULL,"
 					+ " PRIMARY KEY (transportId))";
 
 	private static final String CREATE_INCOMING_KEYS =
 			"CREATE TABLE incomingKeys"
 					+ " (contactId INT NOT NULL,"
-					+ " transportId VARCHAR NOT NULL,"
-					+ " period BIGINT NOT NULL,"
-					+ " tagKey SECRET NOT NULL,"
-					+ " headerKey SECRET NOT NULL,"
+					+ " transportId _STRING NOT NULL,"
+					+ " rotationPeriod BIGINT NOT NULL,"
+					+ " tagKey _SECRET NOT NULL,"
+					+ " headerKey _SECRET NOT NULL,"
 					+ " base BIGINT NOT NULL,"
-					+ " bitmap BINARY NOT NULL,"
-					+ " PRIMARY KEY (contactId, transportId, period),"
+					+ " bitmap _BINARY NOT NULL,"
+					+ " PRIMARY KEY (contactId, transportId, rotationPeriod),"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
 					+ " ON DELETE CASCADE,"
@@ -238,10 +239,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final String CREATE_OUTGOING_KEYS =
 			"CREATE TABLE outgoingKeys"
 					+ " (contactId INT NOT NULL,"
-					+ " transportId VARCHAR NOT NULL,"
-					+ " period BIGINT NOT NULL,"
-					+ " tagKey SECRET NOT NULL,"
-					+ " headerKey SECRET NOT NULL,"
+					+ " transportId _STRING NOT NULL,"
+					+ " rotationPeriod BIGINT NOT NULL,"
+					+ " tagKey _SECRET NOT NULL,"
+					+ " headerKey _SECRET NOT NULL,"
 					+ " stream BIGINT NOT NULL,"
 					+ " PRIMARY KEY (contactId, transportId),"
 					+ " FOREIGN KEY (contactId)"
@@ -275,7 +276,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			Logger.getLogger(JdbcDatabase.class.getName());
 
 	// Different database libraries use different names for certain types
-	private final String hashType, binaryType, counterType, secretType;
+	private final String hashType, secretType, binaryType;
+	private final String counterType, stringType;
 	private final Clock clock;
 
 	// Locking: connectionsLock
@@ -290,12 +292,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private final Lock connectionsLock = new ReentrantLock();
 	private final Condition connectionsChanged = connectionsLock.newCondition();
 
-	JdbcDatabase(String hashType, String binaryType, String counterType,
-			String secretType, Clock clock) {
+	JdbcDatabase(String hashType, String secretType, String binaryType,
+			String counterType, String stringType, Clock clock) {
 		this.hashType = hashType;
+		this.secretType = secretType;
 		this.binaryType = binaryType;
 		this.counterType = counterType;
-		this.secretType = secretType;
+		this.stringType = stringType;
 		this.clock = clock;
 	}
 
@@ -362,7 +365,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
 	List<Migration<Connection>> getMigrations() {
-		return Arrays.asList(new Migration30_31(), new Migration31_32());
+		return Collections.emptyList();
 	}
 
 	private void storeSchemaVersion(Connection txn, int version)
@@ -430,16 +433,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	private String insertTypeNames(String s) {
-		s = s.replaceAll("HASH", hashType);
-		s = s.replaceAll("BINARY", binaryType);
-		s = s.replaceAll("COUNTER", counterType);
-		s = s.replaceAll("SECRET", secretType);
+		s = s.replaceAll("_HASH", hashType);
+		s = s.replaceAll("_SECRET", secretType);
+		s = s.replaceAll("_BINARY", binaryType);
+		s = s.replaceAll("_COUNTER", counterType);
+		s = s.replaceAll("_STRING", stringType);
 		return s;
 	}
 
 	@Override
 	public Connection startTransaction() throws DbException {
-		Connection txn = null;
+		Connection txn;
 		connectionsLock.lock();
 		try {
 			if (closed) throw new DbClosedException();
@@ -547,16 +551,18 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			// Create a contact row
 			String sql = "INSERT INTO contacts"
-					+ " (authorId, name, publicKey, localAuthorId,"
+					+ " (authorId, formatVersion, name, publicKey,"
+					+ " localAuthorId,"
 					+ " verified, active)"
-					+ " VALUES (?, ?, ?, ?, ?, ?)";
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, remote.getId().getBytes());
-			ps.setString(2, remote.getName());
-			ps.setBytes(3, remote.getPublicKey());
-			ps.setBytes(4, local.getBytes());
-			ps.setBoolean(5, verified);
-			ps.setBoolean(6, active);
+			ps.setInt(2, remote.getFormatVersion());
+			ps.setString(3, remote.getName());
+			ps.setBytes(4, remote.getPublicKey());
+			ps.setBytes(5, local.getBytes());
+			ps.setBoolean(6, verified);
+			ps.setBoolean(7, active);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -658,14 +664,16 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO localAuthors"
-					+ " (authorId, name, publicKey, privateKey, created)"
-					+ " VALUES (?, ?, ?, ?, ?)";
+					+ " (authorId, formatVersion, name, publicKey,"
+					+ " privateKey, created)"
+					+ " VALUES (?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, a.getId().getBytes());
-			ps.setString(2, a.getName());
-			ps.setBytes(3, a.getPublicKey());
-			ps.setBytes(4, a.getPrivateKey());
-			ps.setLong(5, a.getTimeCreated());
+			ps.setInt(2, a.getFormatVersion());
+			ps.setString(3, a.getName());
+			ps.setBytes(4, a.getPublicKey());
+			ps.setBytes(5, a.getPrivateKey());
+			ps.setLong(6, a.getTimeCreated());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -822,7 +830,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			// Store the incoming keys
 			String sql = "INSERT INTO incomingKeys (contactId, transportId,"
-					+ " period, tagKey, headerKey, base, bitmap)"
+					+ " rotationPeriod, tagKey, headerKey, base, bitmap)"
 					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
@@ -857,8 +865,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows != 1) throw new DbStateException();
 			ps.close();
 			// Store the outgoing keys
-			sql = "INSERT INTO outgoingKeys (contactId, transportId, period,"
-					+ " tagKey, headerKey, stream)"
+			sql = "INSERT INTO outgoingKeys (contactId, transportId,"
+					+ " rotationPeriod, tagKey, headerKey, stream)"
 					+ " VALUES (?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
@@ -1106,7 +1114,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT authorId, name, publicKey,"
+			String sql = "SELECT authorId, formatVersion, name, publicKey,"
 					+ " localAuthorId, verified, active"
 					+ " FROM contacts"
 					+ " WHERE contactId = ?";
@@ -1115,14 +1123,16 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
 			AuthorId authorId = new AuthorId(rs.getBytes(1));
-			String name = rs.getString(2);
-			byte[] publicKey = rs.getBytes(3);
-			AuthorId localAuthorId = new AuthorId(rs.getBytes(4));
-			boolean verified = rs.getBoolean(5);
-			boolean active = rs.getBoolean(6);
+			int formatVersion = rs.getInt(2);
+			String name = rs.getString(3);
+			byte[] publicKey = rs.getBytes(4);
+			AuthorId localAuthorId = new AuthorId(rs.getBytes(5));
+			boolean verified = rs.getBoolean(6);
+			boolean active = rs.getBoolean(7);
 			rs.close();
 			ps.close();
-			Author author = new Author(authorId, name, publicKey);
+			Author author =
+					new Author(authorId, formatVersion, name, publicKey);
 			return new Contact(c, author, localAuthorId, verified, active);
 		} catch (SQLException e) {
 			tryToClose(rs);
@@ -1137,8 +1147,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT contactId, authorId, name, publicKey,"
-					+ " localAuthorId, verified, active"
+			String sql = "SELECT contactId, authorId, formatVersion, name,"
+					+ " publicKey, localAuthorId, verified, active"
 					+ " FROM contacts";
 			ps = txn.prepareStatement(sql);
 			rs = ps.executeQuery();
@@ -1146,12 +1156,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 			while (rs.next()) {
 				ContactId contactId = new ContactId(rs.getInt(1));
 				AuthorId authorId = new AuthorId(rs.getBytes(2));
-				String name = rs.getString(3);
-				byte[] publicKey = rs.getBytes(4);
-				Author author = new Author(authorId, name, publicKey);
-				AuthorId localAuthorId = new AuthorId(rs.getBytes(5));
-				boolean verified = rs.getBoolean(6);
-				boolean active = rs.getBoolean(7);
+				int formatVersion = rs.getInt(3);
+				String name = rs.getString(4);
+				byte[] publicKey = rs.getBytes(5);
+				Author author =
+						new Author(authorId, formatVersion, name, publicKey);
+				AuthorId localAuthorId = new AuthorId(rs.getBytes(6));
+				boolean verified = rs.getBoolean(7);
+				boolean active = rs.getBoolean(8);
 				contacts.add(new Contact(contactId, author, localAuthorId,
 						verified, active));
 			}
@@ -1194,7 +1206,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT contactId, name, publicKey,"
+			String sql = "SELECT contactId, formatVersion, name, publicKey,"
 					+ " localAuthorId, verified, active"
 					+ " FROM contacts"
 					+ " WHERE authorId = ?";
@@ -1204,12 +1216,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 			List<Contact> contacts = new ArrayList<>();
 			while (rs.next()) {
 				ContactId c = new ContactId(rs.getInt(1));
-				String name = rs.getString(2);
-				byte[] publicKey = rs.getBytes(3);
-				AuthorId localAuthorId = new AuthorId(rs.getBytes(4));
-				boolean verified = rs.getBoolean(5);
-				boolean active = rs.getBoolean(6);
-				Author author = new Author(remote, name, publicKey);
+				int formatVersion = rs.getInt(2);
+				String name = rs.getString(3);
+				byte[] publicKey = rs.getBytes(4);
+				AuthorId localAuthorId = new AuthorId(rs.getBytes(5));
+				boolean verified = rs.getBoolean(6);
+				boolean active = rs.getBoolean(7);
+				Author author =
+						new Author(remote, formatVersion, name, publicKey);
 				contacts.add(new Contact(c, author, localAuthorId, verified,
 						active));
 			}
@@ -1329,19 +1343,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT name, publicKey, privateKey, created"
+			String sql = "SELECT formatVersion, name, publicKey,"
+					+ " privateKey, created"
 					+ " FROM localAuthors"
 					+ " WHERE authorId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, a.getBytes());
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
-			String name = rs.getString(1);
-			byte[] publicKey = rs.getBytes(2);
-			byte[] privateKey = rs.getBytes(3);
-			long created = rs.getLong(4);
-			LocalAuthor localAuthor = new LocalAuthor(a, name, publicKey,
-					privateKey, created);
+			int formatVersion = rs.getInt(1);
+			String name = rs.getString(2);
+			byte[] publicKey = rs.getBytes(3);
+			byte[] privateKey = rs.getBytes(4);
+			long created = rs.getLong(5);
+			LocalAuthor localAuthor = new LocalAuthor(a, formatVersion, name,
+					publicKey, privateKey, created);
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
@@ -1359,19 +1375,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT authorId, name, publicKey, privateKey, created"
+			String sql = "SELECT authorId, formatVersion, name, publicKey,"
+					+ " privateKey, created"
 					+ " FROM localAuthors";
 			ps = txn.prepareStatement(sql);
 			rs = ps.executeQuery();
 			List<LocalAuthor> authors = new ArrayList<>();
 			while (rs.next()) {
 				AuthorId authorId = new AuthorId(rs.getBytes(1));
-				String name = rs.getString(2);
-				byte[] publicKey = rs.getBytes(3);
-				byte[] privateKey = rs.getBytes(4);
-				long created = rs.getLong(5);
-				authors.add(new LocalAuthor(authorId, name, publicKey,
-						privateKey, created));
+				int formatVersion = rs.getInt(2);
+				String name = rs.getString(3);
+				byte[] publicKey = rs.getBytes(4);
+				byte[] privateKey = rs.getBytes(5);
+				long created = rs.getLong(6);
+				authors.add(new LocalAuthor(authorId, formatVersion, name,
+						publicKey, privateKey, created));
 			}
 			rs.close();
 			ps.close();
@@ -1440,7 +1458,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			Set<MessageId> intersection = null;
 			String sql = "SELECT messageId FROM messageMetadata"
 					+ " WHERE groupId = ? AND state = ?"
-					+ " AND key = ? AND value = ?";
+					+ " AND metaKey = ? AND value = ?";
 			for (Entry<String, byte[]> e : query.entrySet()) {
 				ps = txn.prepareStatement(sql);
 				ps.setBytes(1, g.getBytes());
@@ -1472,7 +1490,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT messageId, key, value"
+			String sql = "SELECT messageId, metaKey, value"
 					+ " FROM messageMetadata"
 					+ " WHERE groupId = ? AND state = ?";
 			ps = txn.prepareStatement(sql);
@@ -1517,7 +1535,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM groupMetadata"
+			String sql = "SELECT metaKey, value FROM groupMetadata"
 					+ " WHERE groupId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
@@ -1540,7 +1558,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM messageMetadata"
+			String sql = "SELECT metaKey, value FROM messageMetadata"
 					+ " WHERE state = ? AND messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, DELIVERED.getValue());
@@ -1564,7 +1582,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM messageMetadata"
+			String sql = "SELECT metaKey, value FROM messageMetadata"
 					+ " WHERE (state = ? OR state = ?)"
 					+ " AND messageId = ?";
 			ps = txn.prepareStatement(sql);
@@ -2008,7 +2026,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM settings WHERE namespace = ?";
+			String sql = "SELECT settingKey, value FROM settings"
+					+ " WHERE namespace = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, namespace);
 			rs = ps.executeQuery();
@@ -2031,10 +2050,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			// Retrieve the incoming keys
-			String sql = "SELECT period, tagKey, headerKey, base, bitmap"
+			String sql = "SELECT rotationPeriod, tagKey, headerKey,"
+					+ " base, bitmap"
 					+ " FROM incomingKeys"
 					+ " WHERE transportId = ?"
-					+ " ORDER BY contactId, period";
+					+ " ORDER BY contactId, rotationPeriod";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			rs = ps.executeQuery();
@@ -2051,10 +2071,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs.close();
 			ps.close();
 			// Retrieve the outgoing keys in the same order
-			sql = "SELECT contactId, period, tagKey, headerKey, stream"
+			sql = "SELECT contactId, rotationPeriod, tagKey, headerKey, stream"
 					+ " FROM outgoingKeys"
 					+ " WHERE transportId = ?"
-					+ " ORDER BY contactId, period";
+					+ " ORDER BY contactId, rotationPeriod";
 			ps = txn.prepareStatement(sql);
 			ps.setString(1, t.getString());
 			rs = ps.executeQuery();
@@ -2091,7 +2111,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET stream = stream + 1"
-					+ " WHERE contactId = ? AND transportId = ? AND period = ?";
+					+ " WHERE contactId = ? AND transportId = ?"
+					+ " AND rotationPeriod = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setString(2, t.getString());
@@ -2168,7 +2189,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					g.getBytes(), meta, "groupMetadata", "groupId");
 			if (added.isEmpty()) return;
 			// Insert any keys that don't already exist
-			String sql = "INSERT INTO groupMetadata (groupId, key, value)"
+			String sql = "INSERT INTO groupMetadata (groupId, metaKey, value)"
 					+ " VALUES (?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
@@ -2211,7 +2232,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			// Insert any keys that don't already exist
 			sql = "INSERT INTO messageMetadata"
-					+ " (messageId, groupId, state, key, value)"
+					+ " (messageId, groupId, state, metaKey, value)"
 					+ " VALUES (?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
@@ -2252,7 +2273,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			// Delete any keys that are being removed
 			if (!removed.isEmpty()) {
 				String sql = "DELETE FROM " + tableName
-						+ " WHERE " + columnName + " = ? AND key = ?";
+						+ " WHERE " + columnName + " = ? AND metaKey = ?";
 				ps = txn.prepareStatement(sql);
 				ps.setBytes(1, id);
 				for (String key : removed) {
@@ -2271,7 +2292,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (notRemoved.isEmpty()) return Collections.emptyMap();
 			// Update any keys that already exist
 			String sql = "UPDATE " + tableName + " SET value = ?"
-					+ " WHERE " + columnName + " = ? AND key = ?";
+					+ " WHERE " + columnName + " = ? AND metaKey = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(2, id);
 			for (Entry<String, byte[]> e : notRemoved.entrySet()) {
@@ -2308,7 +2329,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			// Update any settings that already exist
 			String sql = "UPDATE settings SET value = ?"
-					+ " WHERE namespace = ? AND key = ?";
+					+ " WHERE namespace = ? AND settingKey = ?";
 			ps = txn.prepareStatement(sql);
 			for (Entry<String, String> e : s.entrySet()) {
 				ps.setString(1, e.getValue());
@@ -2323,7 +2344,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows > 1) throw new DbStateException();
 			}
 			// Insert any settings that don't already exist
-			sql = "INSERT INTO settings (namespace, key, value)"
+			sql = "INSERT INTO settings (namespace, settingKey, value)"
 					+ " VALUES (?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			int updateIndex = 0, inserted = 0;
@@ -2722,7 +2743,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE incomingKeys SET base = ?, bitmap = ?"
-					+ " WHERE contactId = ? AND transportId = ? AND period = ?";
+					+ " WHERE contactId = ? AND transportId = ?"
+					+ " AND rotationPeriod = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setLong(1, base);
 			ps.setBytes(2, bitmap);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration30_31.java

@@ -1,75 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.db.DbException;
-
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import static java.util.logging.Level.WARNING;
-
-class Migration30_31 implements Migration<Connection> {
-
-	private static final Logger LOG =
-			Logger.getLogger(Migration30_31.class.getName());
-
-	@Override
-	public int getStartVersion() {
-		return 30;
-	}
-
-	@Override
-	public int getEndVersion() {
-		return 31;
-	}
-
-	@Override
-	public void migrate(Connection txn) throws DbException {
-		Statement s = null;
-		try {
-			s = txn.createStatement();
-			// Add groupId column
-			s.execute("ALTER TABLE messageMetadata"
-					+ " ADD COLUMN groupId BINARY(32) AFTER messageId");
-			// Populate groupId column
-			s.execute("UPDATE messageMetadata AS mm SET groupId ="
-					+ " (SELECT groupId FROM messages AS m"
-					+ " WHERE mm.messageId = m.messageId)");
-			// Add not null constraint now column has been populated
-			s.execute("ALTER TABLE messageMetadata"
-					+ " ALTER COLUMN groupId"
-					+ " SET NOT NULL");
-			// Add foreign key constraint
-			s.execute("ALTER TABLE messageMetadata"
-					+ " ADD CONSTRAINT groupIdForeignKey"
-					+ " FOREIGN KEY (groupId)"
-					+ " REFERENCES groups (groupId)"
-					+ " ON DELETE CASCADE");
-			// Add state column
-			s.execute("ALTER TABLE messageMetadata"
-					+ " ADD COLUMN state INT AFTER groupId");
-			// Populate state column
-			s.execute("UPDATE messageMetadata AS mm SET state ="
-					+ " (SELECT state FROM messages AS m"
-					+ " WHERE mm.messageId = m.messageId)");
-			// Add not null constraint now column has been populated
-			s.execute("ALTER TABLE messageMetadata"
-					+ " ALTER COLUMN state"
-					+ " SET NOT NULL");
-		} catch (SQLException e) {
-			tryToClose(s);
-			throw new DbException(e);
-		}
-	}
-
-	private void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration31_32.java

@@ -1,84 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.db.DbException;
-
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import static java.util.logging.Level.WARNING;
-
-class Migration31_32 implements Migration<Connection> {
-
-	private static final Logger LOG =
-			Logger.getLogger(Migration31_32.class.getName());
-
-	@Override
-	public int getStartVersion() {
-		return 31;
-	}
-
-	@Override
-	public int getEndVersion() {
-		return 32;
-	}
-
-	@Override
-	public void migrate(Connection txn) throws DbException {
-		Statement s = null;
-		try {
-			s = txn.createStatement();
-			// Add denormalised columns
-			s.execute("ALTER TABLE statuses ADD COLUMN"
-					+ " (groupId BINARY(32),"
-					+ " timestamp BIGINT,"
-					+ " length INT,"
-					+ " state INT,"
-					+ " groupShared BOOLEAN,"
-					+ " messageShared BOOLEAN,"
-					+ " deleted BOOLEAN)");
-			// Populate columns from messages table
-			s.execute("UPDATE statuses AS s SET (groupId, timestamp, length,"
-					+ " state, messageShared, deleted) ="
-					+ " (SELECT groupId, timestamp, length, state, shared,"
-					+ " raw IS NULL FROM messages AS m"
-					+ " WHERE s.messageId = m.messageId)");
-			// Populate column from groupVisibilities table
-			s.execute("UPDATE statuses AS s SET groupShared ="
-					+ " (SELECT shared FROM groupVisibilities AS gv"
-					+ " WHERE s.contactId = gv.contactId"
-					+ " AND s.groupId = gv.groupId)");
-			// Add not null constraints now columns have been populated
-			s.execute("ALTER TABLE statuses ALTER COLUMN groupId SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN timestamp"
-					+ " SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN length SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN state SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN groupShared"
-					+ " SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN messageShared"
-					+ " SET NOT NULL");
-			s.execute("ALTER TABLE statuses ALTER COLUMN deleted SET NOT NULL");
-			// Add foreign key constraint
-			s.execute("ALTER TABLE statuses"
-					+ " ADD CONSTRAINT statusesForeignKeyGroupId"
-					+ " FOREIGN KEY (groupId)"
-					+ " REFERENCES groups (groupId)"
-					+ " ON DELETE CASCADE");
-		} catch (SQLException e) {
-			tryToClose(s);
-			throw new DbException(e);
-		}
-	}
-
-	private void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/identity/AuthorFactoryImpl.java

@@ -1,61 +1,65 @@
 package org.briarproject.bramble.identity;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
-import org.briarproject.bramble.api.data.BdfWriter;
-import org.briarproject.bramble.api.data.BdfWriterFactory;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.Clock;
-
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
+import org.briarproject.bramble.util.ByteUtils;
+import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
+import static org.briarproject.bramble.api.identity.AuthorId.LABEL;
+import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
+
 @Immutable
 @NotNullByDefault
 class AuthorFactoryImpl implements AuthorFactory {
 
 	private final CryptoComponent crypto;
-	private final BdfWriterFactory bdfWriterFactory;
 	private final Clock clock;
 
 	@Inject
-	AuthorFactoryImpl(CryptoComponent crypto, BdfWriterFactory bdfWriterFactory,
-			Clock clock) {
+	AuthorFactoryImpl(CryptoComponent crypto, Clock clock) {
 		this.crypto = crypto;
-		this.bdfWriterFactory = bdfWriterFactory;
 		this.clock = clock;
 	}
 
 	@Override
 	public Author createAuthor(String name, byte[] publicKey) {
-		return new Author(getId(name, publicKey), name, publicKey);
+		return createAuthor(FORMAT_VERSION, name, publicKey);
+	}
+
+	@Override
+	public Author createAuthor(int formatVersion, String name,
+			byte[] publicKey) {
+		AuthorId id = getId(formatVersion, name, publicKey);
+		return new Author(id, formatVersion, name, publicKey);
 	}
 
 	@Override
 	public LocalAuthor createLocalAuthor(String name, byte[] publicKey,
 			byte[] privateKey) {
-		return new LocalAuthor(getId(name, publicKey), name, publicKey,
-				privateKey, clock.currentTimeMillis());
+		return createLocalAuthor(FORMAT_VERSION, name, publicKey, privateKey);
 	}
 
-	private AuthorId getId(String name, byte[] publicKey) {
-		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		BdfWriter w = bdfWriterFactory.createWriter(out);
-		try {
-			w.writeListStart();
-			w.writeString(name);
-			w.writeRaw(publicKey);
-			w.writeListEnd();
-		} catch (IOException e) {
-			// Shouldn't happen with ByteArrayOutputStream
-			throw new RuntimeException(e);
-		}
-		return new AuthorId(crypto.hash(AuthorId.LABEL, out.toByteArray()));
+	@Override
+	public LocalAuthor createLocalAuthor(int formatVersion, String name,
+			byte[] publicKey, byte[] privateKey) {
+		AuthorId id = getId(formatVersion, name, publicKey);
+		return new LocalAuthor(id, formatVersion, name, publicKey, privateKey,
+				clock.currentTimeMillis());
+	}
+
+	private AuthorId getId(int formatVersion, String name, byte[] publicKey) {
+		byte[] formatVersionBytes = new byte[INT_32_BYTES];
+		ByteUtils.writeUint32(formatVersion, formatVersionBytes, 0);
+		return new AuthorId(crypto.hash(LABEL, formatVersionBytes,
+				StringUtils.toUtf8(name), publicKey));
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/identity/AuthorReader.java

@@ -1,36 +0,0 @@
-package org.briarproject.bramble.identity;
-
-import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.data.BdfReader;
-import org.briarproject.bramble.api.data.ObjectReader;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.identity.AuthorFactory;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.io.IOException;
-
-import javax.annotation.concurrent.Immutable;
-
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
-
-@Immutable
-@NotNullByDefault
-class AuthorReader implements ObjectReader<Author> {
-
-	private final AuthorFactory authorFactory;
-
-	AuthorReader(AuthorFactory authorFactory) {
-		this.authorFactory = authorFactory;
-	}
-
-	@Override
-	public Author readObject(BdfReader r) throws IOException {
-		r.readListStart();
-		String name = r.readString(MAX_AUTHOR_NAME_LENGTH);
-		if (name.length() == 0) throw new FormatException();
-		byte[] publicKey = r.readRaw(MAX_PUBLIC_KEY_LENGTH);
-		r.readListEnd();
-		return authorFactory.createAuthor(name, publicKey);
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/identity/IdentityModule.java

@@ -1,13 +1,7 @@
 package org.briarproject.bramble.identity;
 
-import org.briarproject.bramble.api.crypto.CryptoComponent;
-import org.briarproject.bramble.api.data.BdfWriterFactory;
-import org.briarproject.bramble.api.data.ObjectReader;
-import org.briarproject.bramble.api.db.DatabaseComponent;
-import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.system.Clock;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -24,19 +18,14 @@ public class IdentityModule {
 	}
 
 	@Provides
-	AuthorFactory provideAuthorFactory(CryptoComponent crypto,
-			BdfWriterFactory bdfWriterFactory, Clock clock) {
-		return new AuthorFactoryImpl(crypto, bdfWriterFactory, clock);
+	AuthorFactory provideAuthorFactory(AuthorFactoryImpl authorFactory) {
+		return authorFactory;
 	}
 
 	@Provides
 	@Singleton
-	IdentityManager provideIdentityModule(DatabaseComponent db) {
-		return new IdentityManagerImpl(db);
-	}
-
-	@Provides
-	ObjectReader<Author> provideAuthorReader(AuthorFactory authorFactory) {
-		return new AuthorReader(authorFactory);
+	IdentityManager provideIdentityManager(
+			IdentityManagerImpl identityManager) {
+		return identityManager;
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementConnector.java

@@ -1,6 +1,6 @@
 package org.briarproject.bramble.keyagreement;
 
-import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
@@ -41,7 +41,7 @@ class KeyAgreementConnector {
 			Logger.getLogger(KeyAgreementConnector.class.getName());
 
 	private final Callbacks callbacks;
-	private final CryptoComponent crypto;
+	private final KeyAgreementCrypto keyAgreementCrypto;
 	private final PluginManager pluginManager;
 	private final ConnectionChooser connectionChooser;
 
@@ -53,10 +53,10 @@ class KeyAgreementConnector {
 	private volatile boolean alice = false, stopped = false;
 
 	KeyAgreementConnector(Callbacks callbacks,
-			CryptoComponent crypto, PluginManager pluginManager,
+			KeyAgreementCrypto keyAgreementCrypto, PluginManager pluginManager,
 			ConnectionChooser connectionChooser) {
 		this.callbacks = callbacks;
-		this.crypto = crypto;
+		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.pluginManager = pluginManager;
 		this.connectionChooser = connectionChooser;
 	}
@@ -64,8 +64,8 @@ class KeyAgreementConnector {
 	Payload listen(KeyPair localKeyPair) {
 		LOG.info("Starting BQP listeners");
 		// Derive commitment
-		byte[] commitment = crypto.deriveKeyCommitment(
-				localKeyPair.getPublic().getEncoded());
+		byte[] commitment = keyAgreementCrypto.deriveKeyCommitment(
+				localKeyPair.getPublic());
 		// Start all listeners and collect their descriptors
 		List<TransportDescriptor> descriptors = new ArrayList<>();
 		for (DuplexPlugin plugin : pluginManager.getKeyAgreementPlugins()) {

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementModule.java

@@ -2,7 +2,7 @@ package org.briarproject.bramble.keyagreement;
 
 import org.briarproject.bramble.api.data.BdfReaderFactory;
 import org.briarproject.bramble.api.data.BdfWriterFactory;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementTaskFactory;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
 import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
 import org.briarproject.bramble.api.keyagreement.PayloadParser;
 
@@ -13,9 +13,9 @@ import dagger.Provides;
 public class KeyAgreementModule {
 
 	@Provides
-	KeyAgreementTaskFactory provideKeyAgreementTaskFactory(
-			KeyAgreementTaskFactoryImpl keyAgreementTaskFactory) {
-		return keyAgreementTaskFactory;
+	KeyAgreementTask provideKeyAgreementTask(
+			KeyAgreementTaskImpl keyAgreementTask) {
+		return keyAgreementTask;
 	}
 
 	@Provides

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementProtocol.java

@@ -1,7 +1,10 @@
 package org.briarproject.bramble.keyagreement;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.KeyPair;
+import org.briarproject.bramble.api.crypto.KeyParser;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
@@ -11,6 +14,10 @@ import java.io.IOException;
 import java.security.GeneralSecurityException;
 import java.util.Arrays;
 
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.MASTER_SECRET_LABEL;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.PROTOCOL_VERSION;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.SHARED_SECRET_LABEL;
+
 /**
  * Implementation of the BQP protocol.
  * <p/>
@@ -57,6 +64,7 @@ class KeyAgreementProtocol {
 
 	private final Callbacks callbacks;
 	private final CryptoComponent crypto;
+	private final KeyAgreementCrypto keyAgreementCrypto;
 	private final PayloadEncoder payloadEncoder;
 	private final KeyAgreementTransport transport;
 	private final Payload theirPayload, ourPayload;
@@ -64,11 +72,13 @@ class KeyAgreementProtocol {
 	private final boolean alice;
 
 	KeyAgreementProtocol(Callbacks callbacks, CryptoComponent crypto,
+			KeyAgreementCrypto keyAgreementCrypto,
 			PayloadEncoder payloadEncoder, KeyAgreementTransport transport,
 			Payload theirPayload, Payload ourPayload, KeyPair ourKeyPair,
 			boolean alice) {
 		this.callbacks = callbacks;
 		this.crypto = crypto;
+		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.payloadEncoder = payloadEncoder;
 		this.transport = transport;
 		this.theirPayload = theirPayload;
@@ -86,7 +96,7 @@ class KeyAgreementProtocol {
 	 */
 	SecretKey perform() throws AbortException, IOException {
 		try {
-			byte[] theirPublicKey;
+			PublicKey theirPublicKey;
 			if (alice) {
 				sendKey();
 				// Alice waits here for Bob to scan her QR code, determine his
@@ -105,7 +115,7 @@ class KeyAgreementProtocol {
 				receiveConfirm(s, theirPublicKey);
 				sendConfirm(s, theirPublicKey);
 			}
-			return crypto.deriveMasterSecret(s);
+			return crypto.deriveKey(MASTER_SECRET_LABEL, s);
 		} catch (AbortException e) {
 			sendAbort(e.getCause() != null);
 			throw e;
@@ -116,27 +126,41 @@ class KeyAgreementProtocol {
 		transport.sendKey(ourKeyPair.getPublic().getEncoded());
 	}
 
-	private byte[] receiveKey() throws AbortException {
-		byte[] publicKey = transport.receiveKey();
+	private PublicKey receiveKey() throws AbortException {
+		byte[] publicKeyBytes = transport.receiveKey();
 		callbacks.initialRecordReceived();
-		byte[] expected = crypto.deriveKeyCommitment(publicKey);
-		if (!Arrays.equals(expected, theirPayload.getCommitment()))
+		KeyParser keyParser = crypto.getAgreementKeyParser();
+		try {
+			PublicKey publicKey = keyParser.parsePublicKey(publicKeyBytes);
+			byte[] expected = keyAgreementCrypto.deriveKeyCommitment(publicKey);
+			if (!Arrays.equals(expected, theirPayload.getCommitment()))
+				throw new AbortException();
+			return publicKey;
+		} catch (GeneralSecurityException e) {
 			throw new AbortException();
-		return publicKey;
+		}
 	}
 
-	private SecretKey deriveSharedSecret(byte[] theirPublicKey)
+	private SecretKey deriveSharedSecret(PublicKey theirPublicKey)
 			throws AbortException {
 		try {
-			return crypto.deriveSharedSecret(theirPublicKey, ourKeyPair, alice);
+			byte[] ourPublicKeyBytes = ourKeyPair.getPublic().getEncoded();
+			byte[] theirPublicKeyBytes = theirPublicKey.getEncoded();
+			byte[][] inputs = {
+					new byte[] {PROTOCOL_VERSION},
+					alice ? ourPublicKeyBytes : theirPublicKeyBytes,
+					alice ? theirPublicKeyBytes : ourPublicKeyBytes
+			};
+			return crypto.deriveSharedSecret(SHARED_SECRET_LABEL,
+					theirPublicKey, ourKeyPair, inputs);
 		} catch (GeneralSecurityException e) {
 			throw new AbortException(e);
 		}
 	}
 
-	private void sendConfirm(SecretKey s, byte[] theirPublicKey)
+	private void sendConfirm(SecretKey s, PublicKey theirPublicKey)
 			throws IOException {
-		byte[] confirm = crypto.deriveConfirmationRecord(s,
+		byte[] confirm = keyAgreementCrypto.deriveConfirmationRecord(s,
 				payloadEncoder.encode(theirPayload),
 				payloadEncoder.encode(ourPayload),
 				theirPublicKey, ourKeyPair,
@@ -144,10 +168,10 @@ class KeyAgreementProtocol {
 		transport.sendConfirm(confirm);
 	}
 
-	private void receiveConfirm(SecretKey s, byte[] theirPublicKey)
+	private void receiveConfirm(SecretKey s, PublicKey theirPublicKey)
 			throws AbortException {
 		byte[] confirm = transport.receiveConfirm();
-		byte[] expected = crypto.deriveConfirmationRecord(s,
+		byte[] expected = keyAgreementCrypto.deriveConfirmationRecord(s,
 				payloadEncoder.encode(theirPayload),
 				payloadEncoder.encode(ourPayload),
 				theirPublicKey, ourKeyPair,

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskFactoryImpl.java

@@ -1,41 +0,0 @@
-package org.briarproject.bramble.keyagreement;
-
-import org.briarproject.bramble.api.crypto.CryptoComponent;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementTaskFactory;
-import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginManager;
-
-import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
-import javax.inject.Provider;
-
-@Immutable
-@NotNullByDefault
-class KeyAgreementTaskFactoryImpl implements KeyAgreementTaskFactory {
-
-	private final CryptoComponent crypto;
-	private final EventBus eventBus;
-	private final PayloadEncoder payloadEncoder;
-	private final PluginManager pluginManager;
-	private final Provider<ConnectionChooser> connectionChooserProvider;
-
-	@Inject
-	KeyAgreementTaskFactoryImpl(CryptoComponent crypto, EventBus eventBus,
-			PayloadEncoder payloadEncoder, PluginManager pluginManager,
-			Provider<ConnectionChooser> connectionChooserProvider) {
-		this.crypto = crypto;
-		this.eventBus = eventBus;
-		this.payloadEncoder = payloadEncoder;
-		this.pluginManager = pluginManager;
-		this.connectionChooserProvider = connectionChooserProvider;
-	}
-
-	@Override
-	public KeyAgreementTask createTask() {
-		return new KeyAgreementTaskImpl(crypto, eventBus, payloadEncoder,
-				pluginManager, connectionChooserProvider.get());
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskImpl.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.keyagreement;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.event.EventBus;
@@ -21,6 +22,8 @@ import org.briarproject.bramble.api.plugin.PluginManager;
 import java.io.IOException;
 import java.util.logging.Logger;
 
+import javax.inject.Inject;
+
 import static java.util.logging.Level.WARNING;
 
 @MethodsNotNullByDefault
@@ -32,6 +35,7 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 			Logger.getLogger(KeyAgreementTaskImpl.class.getName());
 
 	private final CryptoComponent crypto;
+	private final KeyAgreementCrypto keyAgreementCrypto;
 	private final EventBus eventBus;
 	private final PayloadEncoder payloadEncoder;
 	private final KeyPair localKeyPair;
@@ -40,15 +44,18 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 	private Payload localPayload;
 	private Payload remotePayload;
 
-	KeyAgreementTaskImpl(CryptoComponent crypto, EventBus eventBus,
+	@Inject
+	KeyAgreementTaskImpl(CryptoComponent crypto,
+			KeyAgreementCrypto keyAgreementCrypto, EventBus eventBus,
 			PayloadEncoder payloadEncoder, PluginManager pluginManager,
 			ConnectionChooser connectionChooser) {
 		this.crypto = crypto;
+		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.eventBus = eventBus;
 		this.payloadEncoder = payloadEncoder;
 		localKeyPair = crypto.generateAgreementKeyPair();
-		connector = new KeyAgreementConnector(this, crypto, pluginManager,
-				connectionChooser);
+		connector = new KeyAgreementConnector(this, keyAgreementCrypto,
+				pluginManager, connectionChooser);
 	}
 
 	@Override
@@ -95,8 +102,8 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 		// Run BQP protocol over the connection
 		LOG.info("Starting BQP protocol");
 		KeyAgreementProtocol protocol = new KeyAgreementProtocol(this, crypto,
-				payloadEncoder, transport, remotePayload, localPayload,
-				localKeyPair, alice);
+				keyAgreementCrypto, payloadEncoder, transport, remotePayload,
+				localPayload, localKeyPair, alice);
 		try {
 			SecretKey master = protocol.perform();
 			KeyAgreementResult result =

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/PayloadEncoderImpl.java

@@ -29,10 +29,10 @@ class PayloadEncoderImpl implements PayloadEncoder {
 	@Override
 	public byte[] encode(Payload p) {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		out.write(PROTOCOL_VERSION);
 		BdfWriter w = bdfWriterFactory.createWriter(out);
 		try {
 			w.writeListStart(); // Payload start
-			w.writeLong(PROTOCOL_VERSION);
 			w.writeRaw(p.getCommitment());
 			for (TransportDescriptor d : p.getTransportDescriptors())
 				w.writeList(d.getDescriptor());

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/PayloadParserImpl.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.keyagreement;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
@@ -39,20 +40,22 @@ class PayloadParserImpl implements PayloadParser {
 	@Override
 	public Payload parse(byte[] raw) throws IOException {
 		ByteArrayInputStream in = new ByteArrayInputStream(raw);
+		// First byte: the protocol version
+		int protocolVersion = in.read();
+		if (protocolVersion == -1) throw new FormatException();
+		if (protocolVersion != PROTOCOL_VERSION)
+			throw new UnsupportedVersionException();
+		// The rest of the payload is a BDF list with one or more elements
 		BdfReader r = bdfReaderFactory.createReader(in);
-		// The payload is a BDF list with two or more elements
 		BdfList payload = r.readList();
-		if (payload.size() < 2) throw new FormatException();
+		if (payload.isEmpty()) throw new FormatException();
 		if (!r.eof()) throw new FormatException();
-		// First element: the protocol version
-		long protocolVersion = payload.getLong(0);
-		if (protocolVersion != PROTOCOL_VERSION) throw new FormatException();
-		// Second element: the public key commitment
-		byte[] commitment = payload.getRaw(1);
+		// First element: the public key commitment
+		byte[] commitment = payload.getRaw(0);
 		if (commitment.length != COMMIT_LENGTH) throw new FormatException();
 		// Remaining elements: transport descriptors
 		List<TransportDescriptor> recognised = new ArrayList<>();
-		for (int i = 2; i < payload.size(); i++) {
+		for (int i = 1; i < payload.size(); i++) {
 			BdfList descriptor = payload.getList(i);
 			long transportId = descriptor.getLong(0);
 			if (transportId == TRANSPORT_ID_BLUETOOTH) {

bramble-core/src/main/java/org/briarproject/bramble/plugin/ConnectionRegistryImpl.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin;
 
+import org.briarproject.bramble.api.Multiset;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -36,14 +37,14 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 	private final Lock lock = new ReentrantLock();
 
 	// The following are locking: lock
-	private final Map<TransportId, Map<ContactId, Integer>> connections;
-	private final Map<ContactId, Integer> contactCounts;
+	private final Map<TransportId, Multiset<ContactId>> connections;
+	private final Multiset<ContactId> contactCounts;
 
 	@Inject
 	ConnectionRegistryImpl(EventBus eventBus) {
 		this.eventBus = eventBus;
 		connections = new HashMap<>();
-		contactCounts = new HashMap<>();
+		contactCounts = new Multiset<>();
 	}
 
 	@Override
@@ -56,21 +57,13 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 		boolean firstConnection = false;
 		lock.lock();
 		try {
-			Map<ContactId, Integer> m = connections.get(t);
+			Multiset<ContactId> m = connections.get(t);
 			if (m == null) {
-				m = new HashMap<>();
+				m = new Multiset<>();
 				connections.put(t, m);
 			}
-			Integer count = m.get(c);
-			if (count == null) m.put(c, 1);
-			else m.put(c, count + 1);
-			count = contactCounts.get(c);
-			if (count == null) {
-				firstConnection = true;
-				contactCounts.put(c, 1);
-			} else {
-				contactCounts.put(c, count + 1);
-			}
+			m.add(c);
+			if (contactCounts.add(c) == 1) firstConnection = true;
 		} finally {
 			lock.unlock();
 		}
@@ -91,23 +84,10 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 		boolean lastConnection = false;
 		lock.lock();
 		try {
-			Map<ContactId, Integer> m = connections.get(t);
+			Multiset<ContactId> m = connections.get(t);
 			if (m == null) throw new IllegalArgumentException();
-			Integer count = m.remove(c);
-			if (count == null) throw new IllegalArgumentException();
-			if (count == 1) {
-				if (m.isEmpty()) connections.remove(t);
-			} else {
-				m.put(c, count - 1);
-			}
-			count = contactCounts.get(c);
-			if (count == null) throw new IllegalArgumentException();
-			if (count == 1) {
-				lastConnection = true;
-				contactCounts.remove(c);
-			} else {
-				contactCounts.put(c, count - 1);
-			}
+			m.remove(c);
+			if (contactCounts.remove(c) == 0) lastConnection = true;
 		} finally {
 			lock.unlock();
 		}
@@ -122,7 +102,7 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 	public Collection<ContactId> getConnectedContacts(TransportId t) {
 		lock.lock();
 		try {
-			Map<ContactId, Integer> m = connections.get(t);
+			Multiset<ContactId> m = connections.get(t);
 			if (m == null) return Collections.emptyList();
 			List<ContactId> ids = new ArrayList<>(m.keySet());
 			if (LOG.isLoggable(INFO))
@@ -137,8 +117,8 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 	public boolean isConnected(ContactId c, TransportId t) {
 		lock.lock();
 		try {
-			Map<ContactId, Integer> m = connections.get(t);
-			return m != null && m.containsKey(c);
+			Multiset<ContactId> m = connections.get(t);
+			return m != null && m.contains(c);
 		} finally {
 			lock.unlock();
 		}
@@ -148,7 +128,7 @@ class ConnectionRegistryImpl implements ConnectionRegistry {
 	public boolean isConnected(ContactId c) {
 		lock.lock();
 		try {
-			return contactCounts.containsKey(c);
+			return contactCounts.contains(c);
 		} finally {
 			lock.unlock();
 		}

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java

@@ -241,11 +241,10 @@ class LanTcpPlugin extends TcpPlugin {
 			}
 			return null;
 		}
+		Socket s = new Socket();
 		try {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
-			Socket s = createSocket();
-			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 			s.connect(remote);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.plugin.tcp;
 
-import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
@@ -48,7 +47,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	private static final Logger LOG =
 			Logger.getLogger(TcpPlugin.class.getName());
 
-	protected final Executor ioExecutor, bindExecutor;
+	protected final Executor ioExecutor;
 	protected final Backoff backoff;
 	protected final DuplexPluginCallback callback;
 	protected final int maxLatency, maxIdleTime, socketTimeout;
@@ -91,8 +90,6 @@ abstract class TcpPlugin implements DuplexPlugin {
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
-		// Don't execute more than one bind operation at a time
-		bindExecutor = new PoliteExecutor("TcpPlugin", ioExecutor, 1);
 	}
 
 	@Override
@@ -113,9 +110,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 
 	protected void bind() {
-		bindExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			if (!running) return;
-			if (socket != null && !socket.isClosed()) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -247,11 +243,10 @@ abstract class TcpPlugin implements DuplexPlugin {
 				}
 				continue;
 			}
+			Socket s = new Socket();
 			try {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
-				Socket s = createSocket();
-				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 				s.connect(remote);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
@@ -266,10 +261,6 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return null;
 	}
 
-	protected Socket createSocket() throws IOException {
-		return new Socket();
-	}
-
 	@Nullable
 	InetSocketAddress parseSocketAddress(String ipPort) {
 		if (StringUtils.isNullOrEmpty(ipPort)) return null;

bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java

@@ -58,7 +58,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		this.metadataParser = metadataParser;
 		this.contactGroupFactory = contactGroupFactory;
 		this.clock = clock;
-		localGroup = contactGroupFactory.createLocalGroup(CLIENT_ID);
+		localGroup = contactGroupFactory.createLocalGroup(CLIENT_ID,
+				CLIENT_VERSION);
 	}
 
 	@Override
@@ -130,8 +131,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public Map<TransportId, TransportProperties> getLocalProperties()
 			throws DbException {
 		Map<TransportId, TransportProperties> local;
-		// TODO: Transaction can be read-only when code is simplified
-		Transaction txn = db.startTransaction(false);
+		Transaction txn = db.startTransaction(true);
 		try {
 			local = getLocalProperties(txn);
 			db.commitTransaction(txn);
@@ -166,8 +166,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			throws DbException {
 		try {
 			TransportProperties p = null;
-			// TODO: Transaction can be read-only when code is simplified
-			Transaction txn = db.startTransaction(false);
+			Transaction txn = db.startTransaction(true);
 			try {
 				// Find the latest local update
 				LatestUpdate latest = findLatest(txn, localGroup.getId(), t,
@@ -193,8 +192,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public Map<ContactId, TransportProperties> getRemoteProperties(
 			TransportId t) throws DbException {
 		Map<ContactId, TransportProperties> remote = new HashMap<>();
-		// TODO: Transaction can be read-only when code is simplified
-		Transaction txn = db.startTransaction(false);
+		Transaction txn = db.startTransaction(true);
 		try {
 			for (Contact c : db.getContacts(txn))
 				remote.put(c.getId(), getRemoteProperties(txn, c, t));
@@ -228,8 +226,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException {
 		TransportProperties p;
-		// TODO: Transaction can be read-only when code is simplified
-		Transaction txn = db.startTransaction(false);
+		Transaction txn = db.startTransaction(true);
 		try {
 			p = getRemoteProperties(txn, db.getContact(txn, c), t);
 			db.commitTransaction(txn);
@@ -292,7 +289,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	}
 
 	private Group getContactGroup(Contact c) {
-		return contactGroupFactory.createContactGroup(CLIENT_ID, c);
+		return contactGroupFactory.createContactGroup(CLIENT_ID,
+				CLIENT_VERSION, c);
 	}
 
 	private void storeMessage(Transaction txn, GroupId g, TransportId t,
@@ -319,7 +317,6 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 
 	private Map<TransportId, LatestUpdate> findLatestLocal(Transaction txn)
 			throws DbException, FormatException {
-		// TODO: This can be simplified before 1.0
 		Map<TransportId, LatestUpdate> latestUpdates = new HashMap<>();
 		Map<MessageId, BdfDictionary> metadata = clientHelper
 				.getMessageMetadataAsDictionary(txn, localGroup.getId());
@@ -327,17 +324,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			BdfDictionary meta = e.getValue();
 			TransportId t = new TransportId(meta.getString("transportId"));
 			long version = meta.getLong("version");
-			LatestUpdate latest = latestUpdates.get(t);
-			if (latest == null) {
-				latestUpdates.put(t, new LatestUpdate(e.getKey(), version));
-			} else if (version > latest.version) {
-				// This update is newer - delete the previous one
-				db.removeMessage(txn, latest.messageId);
-				latestUpdates.put(t, new LatestUpdate(e.getKey(), version));
-			} else {
-				// We've already found a newer update - delete this one
-				db.removeMessage(txn, e.getKey());
-			}
+			latestUpdates.put(t, new LatestUpdate(e.getKey(), version));
 		}
 		return latestUpdates;
 	}
@@ -345,38 +332,16 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Nullable
 	private LatestUpdate findLatest(Transaction txn, GroupId g, TransportId t,
 			boolean local) throws DbException, FormatException {
-		// TODO: This can be simplified before 1.0
-		LatestUpdate latest = null;
 		Map<MessageId, BdfDictionary> metadata =
 				clientHelper.getMessageMetadataAsDictionary(txn, g);
 		for (Entry<MessageId, BdfDictionary> e : metadata.entrySet()) {
 			BdfDictionary meta = e.getValue();
 			if (meta.getString("transportId").equals(t.getString())
 					&& meta.getBoolean("local") == local) {
-				long version = meta.getLong("version");
-				if (latest == null) {
-					latest = new LatestUpdate(e.getKey(), version);
-				} else if (version > latest.version) {
-					// This update is newer - delete the previous one
-					if (local) {
-						db.removeMessage(txn, latest.messageId);
-					} else {
-						db.deleteMessage(txn, latest.messageId);
-						db.deleteMessageMetadata(txn, latest.messageId);
-					}
-					latest = new LatestUpdate(e.getKey(), version);
-				} else {
-					// We've already found a newer update - delete this one
-					if (local) {
-						db.removeMessage(txn, e.getKey());
-					} else {
-						db.deleteMessage(txn, e.getKey());
-						db.deleteMessageMetadata(txn, e.getKey());
-					}
-				}
+				return new LatestUpdate(e.getKey(), meta.getLong("version"));
 			}
 		}
-		return latest;
+		return null;
 	}
 
 	private TransportProperties parseProperties(BdfList message)

bramble-core/src/main/java/org/briarproject/bramble/sync/GroupFactoryImpl.java

@@ -6,11 +6,16 @@ import org.briarproject.bramble.api.sync.ClientId;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.GroupFactory;
 import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.sync.GroupId.LABEL;
+import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
+import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
+
 @Immutable
 @NotNullByDefault
 class GroupFactoryImpl implements GroupFactory {
@@ -23,9 +28,12 @@ class GroupFactoryImpl implements GroupFactory {
 	}
 
 	@Override
-	public Group createGroup(ClientId c, byte[] descriptor) {
-		byte[] hash = crypto.hash(GroupId.LABEL,
-				StringUtils.toUtf8(c.getString()), descriptor);
+	public Group createGroup(ClientId c, int clientVersion, byte[] descriptor) {
+		byte[] clientVersionBytes = new byte[INT_32_BYTES];
+		ByteUtils.writeUint32(clientVersion, clientVersionBytes, 0);
+		byte[] hash = crypto.hash(LABEL, new byte[] {PROTOCOL_VERSION},
+				StringUtils.toUtf8(c.getString()), clientVersionBytes,
+				descriptor);
 		return new Group(new GroupId(hash), c, descriptor);
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/MessageFactoryImpl.java

@@ -12,8 +12,10 @@ import org.briarproject.bramble.util.ByteUtils;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.sync.MessageId.LABEL;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
+import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 
 @Immutable
 @NotNullByDefault
@@ -32,9 +34,9 @@ class MessageFactoryImpl implements MessageFactory {
 			throw new IllegalArgumentException();
 		byte[] timeBytes = new byte[ByteUtils.INT_64_BYTES];
 		ByteUtils.writeUint64(timestamp, timeBytes, 0);
-		byte[] idHash =
-				crypto.hash(MessageId.LABEL, g.getBytes(), timeBytes, body);
-		MessageId id = new MessageId(idHash);
+		byte[] hash = crypto.hash(LABEL, new byte[] {PROTOCOL_VERSION},
+				g.getBytes(), timeBytes, body);
+		MessageId id = new MessageId(hash);
 		byte[] raw = new byte[MESSAGE_HEADER_LENGTH + body.length];
 		System.arraycopy(g.getBytes(), 0, raw, 0, UniqueId.LENGTH);
 		ByteUtils.writeUint64(timestamp, raw, UniqueId.LENGTH);

bramble-core/src/main/java/org/briarproject/bramble/system/SystemModule.java

@@ -4,9 +4,8 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.Scheduler;
 
-import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.ScheduledThreadPoolExecutor;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -26,10 +25,7 @@ public class SystemModule {
 	private final ScheduledExecutorService scheduler;
 
 	public SystemModule() {
-		// Discard tasks that are submitted during shutdown
-		RejectedExecutionHandler policy =
-				new ScheduledThreadPoolExecutor.DiscardPolicy();
-		scheduler = new ScheduledThreadPoolExecutor(1, policy);
+		scheduler = Executors.newSingleThreadScheduledExecutor();
 	}
 
 	@Provides

bramble-core/src/main/java/org/briarproject/bramble/transport/TransportKeyManagerFactoryImpl.java

@@ -1,6 +1,6 @@
 package org.briarproject.bramble.transport;
 
-import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -20,17 +20,18 @@ class TransportKeyManagerFactoryImpl implements
 		TransportKeyManagerFactory {
 
 	private final DatabaseComponent db;
-	private final CryptoComponent crypto;
+	private final TransportCrypto transportCrypto;
 	private final Executor dbExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final Clock clock;
 
 	@Inject
-	TransportKeyManagerFactoryImpl(DatabaseComponent db, CryptoComponent crypto,
+	TransportKeyManagerFactoryImpl(DatabaseComponent db,
+			TransportCrypto transportCrypto,
 			@DatabaseExecutor Executor dbExecutor,
 			@Scheduler ScheduledExecutorService scheduler, Clock clock) {
 		this.db = db;
-		this.crypto = crypto;
+		this.transportCrypto = transportCrypto;
 		this.dbExecutor = dbExecutor;
 		this.scheduler = scheduler;
 		this.clock = clock;
@@ -39,8 +40,8 @@ class TransportKeyManagerFactoryImpl implements
 	@Override
 	public TransportKeyManager createTransportKeyManager(
 			TransportId transportId, long maxLatency) {
-		return new TransportKeyManagerImpl(db, crypto, dbExecutor, scheduler,
-				clock, transportId, maxLatency);
+		return new TransportKeyManagerImpl(db, transportCrypto, dbExecutor,
+				scheduler, clock, transportId, maxLatency);
 	}
 
 }

bramble-core/src/main/java/org/briarproject/bramble/transport/TransportKeyManagerImpl.java

@@ -2,8 +2,8 @@ package org.briarproject.bramble.transport;
 
 import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
@@ -41,7 +41,7 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			Logger.getLogger(TransportKeyManagerImpl.class.getName());
 
 	private final DatabaseComponent db;
-	private final CryptoComponent crypto;
+	private final TransportCrypto transportCrypto;
 	private final Executor dbExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final Clock clock;
@@ -54,11 +54,12 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	private final Map<ContactId, MutableOutgoingKeys> outContexts;
 	private final Map<ContactId, MutableTransportKeys> keys;
 
-	TransportKeyManagerImpl(DatabaseComponent db, CryptoComponent crypto,
-			Executor dbExecutor, @Scheduler ScheduledExecutorService scheduler,
-			Clock clock, TransportId transportId, long maxLatency) {
+	TransportKeyManagerImpl(DatabaseComponent db,
+			TransportCrypto transportCrypto, Executor dbExecutor,
+			@Scheduler ScheduledExecutorService scheduler, Clock clock,
+			TransportId transportId, long maxLatency) {
 		this.db = db;
-		this.crypto = crypto;
+		this.transportCrypto = transportCrypto;
 		this.dbExecutor = dbExecutor;
 		this.scheduler = scheduler;
 		this.clock = clock;
@@ -99,7 +100,8 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		for (Entry<ContactId, TransportKeys> e : keys.entrySet()) {
 			ContactId c = e.getKey();
 			TransportKeys k = e.getValue();
-			TransportKeys k1 = crypto.rotateTransportKeys(k, rotationPeriod);
+			TransportKeys k1 =
+					transportCrypto.rotateTransportKeys(k, rotationPeriod);
 			if (k1.getRotationPeriod() > k.getRotationPeriod())
 				rotationResult.rotated.put(c, k1);
 			rotationResult.current.put(c, k1);
@@ -127,7 +129,7 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		for (long streamNumber : inKeys.getWindow().getUnseen()) {
 			TagContext tagCtx = new TagContext(c, inKeys, streamNumber);
 			byte[] tag = new byte[TAG_LENGTH];
-			crypto.encodeTag(tag, inKeys.getTagKey(), PROTOCOL_VERSION,
+			transportCrypto.encodeTag(tag, inKeys.getTagKey(), PROTOCOL_VERSION,
 					streamNumber);
 			inContexts.put(new Bytes(tag), tagCtx);
 		}
@@ -162,11 +164,11 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			// Work out what rotation period the timestamp belongs to
 			long rotationPeriod = timestamp / rotationPeriodLength;
 			// Derive the transport keys
-			TransportKeys k = crypto.deriveTransportKeys(transportId, master,
-					rotationPeriod, alice);
+			TransportKeys k = transportCrypto.deriveTransportKeys(transportId,
+					master, rotationPeriod, alice);
 			// Rotate the keys to the current rotation period if necessary
 			rotationPeriod = clock.currentTimeMillis() / rotationPeriodLength;
-			k = crypto.rotateTransportKeys(k, rotationPeriod);
+			k = transportCrypto.rotateTransportKeys(k, rotationPeriod);
 			// Initialise mutable state for the contact
 			addKeys(c, new MutableTransportKeys(k));
 			// Write the keys back to the DB
@@ -234,8 +236,8 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			// Add tags for any stream numbers added to the window
 			for (long streamNumber : change.getAdded()) {
 				byte[] addTag = new byte[TAG_LENGTH];
-				crypto.encodeTag(addTag, inKeys.getTagKey(), PROTOCOL_VERSION,
-						streamNumber);
+				transportCrypto.encodeTag(addTag, inKeys.getTagKey(),
+						PROTOCOL_VERSION, streamNumber);
 				inContexts.put(new Bytes(addTag), new TagContext(
 						tagCtx.contactId, inKeys, streamNumber));
 			}
@@ -243,7 +245,7 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			for (long streamNumber : change.getRemoved()) {
 				if (streamNumber == tagCtx.streamNumber) continue;
 				byte[] removeTag = new byte[TAG_LENGTH];
-				crypto.encodeTag(removeTag, inKeys.getTagKey(),
+				transportCrypto.encodeTag(removeTag, inKeys.getTagKey(),
 						PROTOCOL_VERSION, streamNumber);
 				inContexts.remove(new Bytes(removeTag));
 			}

bramble-core/src/test/java/org/briarproject/bramble/client/ClientHelperImplTest.java

@@ -15,6 +15,8 @@ import org.briarproject.bramble.api.data.MetadataParser;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
@@ -31,9 +33,14 @@ import java.security.GeneralSecurityException;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Random;
 
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
+import static org.briarproject.bramble.test.TestUtils.getAuthor;
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
@@ -54,7 +61,8 @@ public class ClientHelperImplTest extends BrambleTestCase {
 			context.mock(MetadataEncoder.class);
 	private final CryptoComponent cryptoComponent =
 			context.mock(CryptoComponent.class);
-	private final ClientHelper clientHelper;
+	private final AuthorFactory authorFactory =
+			context.mock(AuthorFactory.class);
 
 	private final GroupId groupId = new GroupId(getRandomId());
 	private final BdfDictionary dictionary = new BdfDictionary();
@@ -66,17 +74,15 @@ public class ClientHelperImplTest extends BrambleTestCase {
 	private final Metadata metadata = new Metadata();
 	private final BdfList list = BdfList.of("Sign this!", getRandomBytes(42));
 	private final String label = StringUtils.getRandomString(5);
+	private final Author author = getAuthor();
 
-	public ClientHelperImplTest() {
-		clientHelper =
-				new ClientHelperImpl(db, messageFactory, bdfReaderFactory,
-						bdfWriterFactory, metadataParser, metadataEncoder,
-						cryptoComponent);
-	}
+	private final ClientHelper clientHelper = new ClientHelperImpl(db,
+			messageFactory, bdfReaderFactory, bdfWriterFactory, metadataParser,
+			metadataEncoder, cryptoComponent, authorFactory);
 
 	@Test
 	public void testAddLocalMessage() throws Exception {
-		boolean shared = true;
+		boolean shared = new Random().nextBoolean();
 		Transaction txn = new Transaction(null, false);
 
 		context.checking(new Expectations() {{
@@ -180,8 +186,7 @@ public class ClientHelperImplTest extends BrambleTestCase {
 			oneOf(db).endTransaction(txn);
 		}});
 
-		assertEquals(map,
-				clientHelper.getMessageMetadataAsDictionary(groupId));
+		assertEquals(map, clientHelper.getMessageMetadataAsDictionary(groupId));
 		context.assertIsSatisfied();
 	}
 
@@ -318,8 +323,7 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		}});
 
 		try {
-			clientHelper
-					.verifySignature(label, rawMessage, publicKey, list);
+			clientHelper.verifySignature(label, rawMessage, publicKey, list);
 			fail();
 		} catch (GeneralSecurityException e) {
 			// expected
@@ -327,6 +331,166 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		}
 	}
 
+	@Test
+	public void testParsesAndEncodesAuthor() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(authorFactory).createAuthor(author.getFormatVersion(),
+					author.getName(), author.getPublicKey());
+			will(returnValue(author));
+		}});
+
+		BdfList authorList = clientHelper.toList(author);
+		assertEquals(author, clientHelper.parseAndValidateAuthor(authorList));
+	}
+
+	@Test
+	public void testAcceptsValidAuthor() throws Exception {
+		BdfList authorList = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				author.getPublicKey()
+		);
+
+		context.checking(new Expectations() {{
+			oneOf(authorFactory).createAuthor(author.getFormatVersion(),
+					author.getName(), author.getPublicKey());
+			will(returnValue(author));
+		}});
+
+		assertEquals(author, clientHelper.parseAndValidateAuthor(authorList));
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsTooShortAuthor() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsTooLongAuthor() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				author.getPublicKey(),
+				"foo"
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNullFormatVersion() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				null,
+				author.getName(),
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNonIntegerFormatVersion()
+			throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				"foo",
+				author.getName(),
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithUnknownFormatVersion() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion() + 1,
+				author.getName(),
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithTooShortName() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				"",
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithTooLongName() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				getRandomString(MAX_AUTHOR_NAME_LENGTH + 1),
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNullName() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				null,
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNonStringName() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				getRandomBytes(5),
+				author.getPublicKey()
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithTooShortPublicKey() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				new byte[0]
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithTooLongPublicKey() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				getRandomBytes(MAX_PUBLIC_KEY_LENGTH + 1)
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNullPublicKey() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				null
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
+	@Test(expected = FormatException.class)
+	public void testRejectsAuthorWithNonRawPublicKey() throws Exception {
+		BdfList invalidAuthor = BdfList.of(
+				author.getFormatVersion(),
+				author.getName(),
+				"foo"
+		);
+		clientHelper.parseAndValidateAuthor(invalidAuthor);
+	}
+
 	private byte[] expectToByteArray(BdfList list) throws Exception {
 		BdfWriter bdfWriter = context.mock(BdfWriter.class);
 
@@ -352,5 +516,4 @@ public class ClientHelperImplTest extends BrambleTestCase {
 			will(returnValue(eof));
 		}});
 	}
-
 }

bramble-core/src/test/java/org/briarproject/bramble/contact/ContactManagerImplTest.java

@@ -18,8 +18,9 @@ import org.junit.Test;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Random;
 
-import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getAuthor;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
 import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 import static org.junit.Assert.assertEquals;
@@ -32,9 +33,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	private final KeyManager keyManager = context.mock(KeyManager.class);
 	private final ContactManager contactManager;
 	private final ContactId contactId = new ContactId(42);
-	private final Author remote =
-			new Author(new AuthorId(getRandomId()), "remote",
-					getRandomBytes(42));
+	private final Author remote = getAuthor();
 	private final AuthorId local = new AuthorId(getRandomId());
 	private final boolean verified = false, active = true;
 	private final Contact contact =
@@ -47,8 +46,8 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testAddContact() throws Exception {
 		SecretKey master = getSecretKey();
-		long timestamp = 42;
-		boolean alice = true;
+		long timestamp = System.currentTimeMillis();
+		boolean alice = new Random().nextBoolean();
 		Transaction txn = new Transaction(null, false);
 
 		context.checking(new Expectations() {{

bramble-core/src/test/java/org/briarproject/bramble/crypto/Blake2bDigestTest.java

@@ -3,75 +3,76 @@ package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.util.StringUtils;
 import org.junit.Test;
+import org.spongycastle.crypto.digests.Blake2bDigest;
 
 import java.util.Random;
 
 import static org.junit.Assert.assertArrayEquals;
 
-public class Blake2sDigestTest extends BrambleTestCase {
+public class Blake2bDigestTest extends BrambleTestCase {
 
-	// Vectors from BLAKE2 web site: https://blake2.net/blake2s-test.txt
-	private static final String[][] keyedTestVectors = {
+	// Vectors from BLAKE2 web site: https://blake2.net/Blake2b-test.txt
+	private static final String[][] KEYED_TEST_VECTORS = {
 			// input/message, key, hash
 			{
 					"",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"48a8997da407876b3d79c0d92325ad3b89cbb754d86ab71aee047ad345fd2c49",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"10ebb67700b1868efb4417987acf4690ae9d972fb7a590c2f02871799aaa4786b5e996e8f0f4eb981fc214b005f42d2ff4233499391653df7aefcbc13fc51568",
 			},
 			{
 					"00",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"40d15fee7c328830166ac3f918650f807e7e01e177258cdc0a39b11f598066f1",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"961f6dd1e4dd30f63901690c512e78e4b45e4742ed197c3c5e45c549fd25f2e4187b0bc9fe30492b16b0d0bc4ef9b0f34c7003fac09a5ef1532e69430234cebd",
 			},
 			{
 					"0001",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"6bb71300644cd3991b26ccd4d274acd1adeab8b1d7914546c1198bbe9fc9d803",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"da2cfbe2d8409a0f38026113884f84b50156371ae304c4430173d08a99d9fb1b983164a3770706d537f49e0c916d9f32b95cc37a95b99d857436f0232c88a965",
 			},
 			{
 					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"172ffc67153d12e0ca76a8b6cd5d4731885b39ce0cac93a8972a18006c8b8baf",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"f1aa2b044f8f0c638a3f362e677b5d891d6fd2ab0765f6ee1e4987de057ead357883d9b405b9d609eea1b869d97fb16d9b51017c553f3b93c0a1e0f1296fedcd",
 			},
 			{
 					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"4f8ce1e51d2fe7f24043a904d898ebfc91975418753413aa099b795ecb35cedb",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"c230f0802679cb33822ef8b3b21bf7a9a28942092901d7dac3760300831026cf354c9232df3e084d9903130c601f63c1f4a4a4b8106e468cd443bbe5a734f45f",
 			},
 			{
 					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfe",
-					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
-					"3fb735061abc519dfe979e54c1ee5bfad0a9d858b3315bad34bde999efd724dd",
+					"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f",
+					"142709d62e28fcccd0af97fad0f8465b971e82201dc51070faa0372aa43e92484be1c1e73ba10906d5d1853db6a4106e0a7bf9800d373d6dee2d46d62ef2a461",
 			},
 	};
 
 	@Test
 	public void testDigestWithKeyedTestVectors() {
-		Blake2sDigest digest = new Blake2sDigest(StringUtils.fromHexString(
-				keyedTestVectors[0][1]));
-		for (String[] keyedTestVector : keyedTestVectors) {
+		for (String[] keyedTestVector : KEYED_TEST_VECTORS) {
 			byte[] input = StringUtils.fromHexString(keyedTestVector[0]);
-			digest.reset();
+			byte[] key = StringUtils.fromHexString(keyedTestVector[1]);
+			byte[] expected = StringUtils.fromHexString(keyedTestVector[2]);
 
+			Blake2bDigest digest = new Blake2bDigest(key);
 			digest.update(input, 0, input.length);
-			byte[] hash = new byte[32];
+			byte[] hash = new byte[64];
 			digest.doFinal(hash, 0);
 
-			assertArrayEquals(StringUtils.fromHexString(keyedTestVector[2]),
-					hash);
+			assertArrayEquals(expected, hash);
 		}
 	}
 
 	@Test
 	public void testDigestWithKeyedTestVectorsAndRandomUpdate() {
-		Blake2sDigest digest = new Blake2sDigest(StringUtils.fromHexString(
-				keyedTestVectors[0][1]));
 		Random random = new Random();
 		for (int i = 0; i < 100; i++) {
-			for (String[] keyedTestVector : keyedTestVectors) {
+			for (String[] keyedTestVector : KEYED_TEST_VECTORS) {
 				byte[] input = StringUtils.fromHexString(keyedTestVector[0]);
-				if (input.length < 3) continue;
-				digest.reset();
+				if (input.length == 0) continue;
+				byte[] key = StringUtils.fromHexString(keyedTestVector[1]);
+				byte[] expected = StringUtils.fromHexString(keyedTestVector[2]);
+
+				Blake2bDigest digest = new Blake2bDigest(key);
 
 				int pos = random.nextInt(input.length);
 				if (pos > 0)
@@ -80,11 +81,10 @@ public class Blake2sDigestTest extends BrambleTestCase {
 				if (pos < (input.length - 1))
 					digest.update(input, pos + 1, input.length - (pos + 1));
 
-				byte[] hash = new byte[32];
+				byte[] hash = new byte[64];
 				digest.doFinal(hash, 0);
 
-				assertArrayEquals(StringUtils.fromHexString(keyedTestVector[2]),
-						hash);
+				assertArrayEquals(expected, hash);
 			}
 		}
 	}
@@ -98,12 +98,12 @@ public class Blake2sDigestTest extends BrambleTestCase {
 		byte[] input = new byte[key.length + 1];
 		for (byte i = 0; i < input.length; i++) input[i] = i;
 		// Hash the input
-		Blake2sDigest digest = new Blake2sDigest(key);
+		Blake2bDigest digest = new Blake2bDigest(key);
 		digest.update(input, 0, input.length);
 		byte[] hash = new byte[digest.getDigestSize()];
 		digest.doFinal(hash, 0);
 		// Create a second instance, hash the input without calling doFinal()
-		Blake2sDigest digest1 = new Blake2sDigest(key);
+		Blake2bDigest digest1 = new Blake2bDigest(key);
 		digest1.update(input, 0, input.length);
 		// Reset the second instance and hash the input again
 		digest1.reset();
@@ -116,9 +116,10 @@ public class Blake2sDigestTest extends BrambleTestCase {
 
 	// Self-test routine from https://tools.ietf.org/html/rfc7693#appendix-E
 	private static final String SELF_TEST_RESULT =
-			"6A411F08CE25ADCDFB02ABA641451CEC53C598B24F4FC787FBDC88797F4C1DFE";
-	private static final int[] SELF_TEST_DIGEST_LEN = {16, 20, 28, 32};
-	private static final int[] SELF_TEST_INPUT_LEN = {0, 3, 64, 65, 255, 1024};
+			"C23A7800D98123BD10F506C61E29DA5603D763B8BBAD2E737F5E765A7BCCD475";
+	private static final int[] SELF_TEST_DIGEST_LEN = {20, 32, 48, 64};
+	private static final int[] SELF_TEST_INPUT_LEN =
+			{0, 3, 128, 129, 255, 1024};
 
 	private static byte[] selfTestSequence(int len, int seed) {
 		int a = 0xDEAD4BAD * seed;
@@ -138,8 +139,8 @@ public class Blake2sDigestTest extends BrambleTestCase {
 
 	@Test
 	public void runSelfTest() {
-		Blake2sDigest testDigest = new Blake2sDigest();
-		byte[] md = new byte[32];
+		Blake2bDigest testDigest = new Blake2bDigest(256);
+		byte[] md = new byte[64];
 
 		for (int i = 0; i < 4; i++) {
 			int outlen = SELF_TEST_DIGEST_LEN[i];
@@ -148,7 +149,7 @@ public class Blake2sDigestTest extends BrambleTestCase {
 
 				// unkeyed hash
 				byte[] in = selfTestSequence(inlen, inlen);
-				Blake2sDigest unkeyedDigest = new Blake2sDigest(outlen * 8);
+				Blake2bDigest unkeyedDigest = new Blake2bDigest(outlen * 8);
 				unkeyedDigest.update(in, 0, inlen);
 				unkeyedDigest.doFinal(md, 0);
 				// hash the hash
@@ -156,7 +157,7 @@ public class Blake2sDigestTest extends BrambleTestCase {
 
 				// keyed hash
 				byte[] key = selfTestSequence(outlen, outlen);
-				Blake2sDigest keyedDigest = new Blake2sDigest(key, outlen, null,
+				Blake2bDigest keyedDigest = new Blake2bDigest(key, outlen, null,
 						null);
 				keyedDigest.update(in, 0, inlen);
 				keyedDigest.doFinal(md, 0);

bramble-core/src/test/java/org/briarproject/bramble/crypto/EdSignatureTest.java

@@ -0,0 +1,169 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.crypto.KeyPair;
+import org.junit.Test;
+
+import java.security.GeneralSecurityException;
+
+import static org.briarproject.bramble.util.StringUtils.fromHexString;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertTrue;
+
+public class EdSignatureTest extends SignatureTest {
+
+	// Test vectors from RFC 8032: secret key, public key, message, signature
+	// https://tools.ietf.org/html/rfc8032#section-7.1
+	private static final String[][] TEST_VECTORS = {{
+			"9d61b19deffd5a60ba844af492ec2cc4" +
+					"4449c5697b326919703bac031cae7f60",
+			"d75a980182b10ab7d54bfed3c964073a" +
+					"0ee172f3daa62325af021a68f707511a",
+			"",
+			"e5564300c360ac729086e2cc806e828a" +
+					"84877f1eb8e5d974d873e06522490155" +
+					"5fb8821590a33bacc61e39701cf9b46b" +
+					"d25bf5f0595bbe24655141438e7a100b"
+	}, {
+			"4ccd089b28ff96da9db6c346ec114e0f" +
+					"5b8a319f35aba624da8cf6ed4fb8a6fb",
+			"3d4017c3e843895a92b70aa74d1b7ebc" +
+					"9c982ccf2ec4968cc0cd55f12af4660c",
+			"72",
+			"92a009a9f0d4cab8720e820b5f642540" +
+					"a2b27b5416503f8fb3762223ebdb69da" +
+					"085ac1e43e15996e458f3613d0f11d8c" +
+					"387b2eaeb4302aeeb00d291612bb0c00"
+	}, {
+			"c5aa8df43f9f837bedb7442f31dcb7b1" +
+					"66d38535076f094b85ce3a2e0b4458f7",
+			"fc51cd8e6218a1a38da47ed00230f058" +
+					"0816ed13ba3303ac5deb911548908025",
+			"af82",
+			"6291d657deec24024827e69c3abe01a3" +
+					"0ce548a284743a445e3680d7db5ac3ac" +
+					"18ff9b538d16f290ae67f760984dc659" +
+					"4a7c15e9716ed28dc027beceea1ec40a"
+	}, {
+			"f5e5767cf153319517630f226876b86c" +
+					"8160cc583bc013744c6bf255f5cc0ee5",
+			"278117fc144c72340f67d0f2316e8386" +
+					"ceffbf2b2428c9c51fef7c597f1d426e",
+			"08b8b2b733424243760fe426a4b54908" +
+					"632110a66c2f6591eabd3345e3e4eb98" +
+					"fa6e264bf09efe12ee50f8f54e9f77b1" +
+					"e355f6c50544e23fb1433ddf73be84d8" +
+					"79de7c0046dc4996d9e773f4bc9efe57" +
+					"38829adb26c81b37c93a1b270b20329d" +
+					"658675fc6ea534e0810a4432826bf58c" +
+					"941efb65d57a338bbd2e26640f89ffbc" +
+					"1a858efcb8550ee3a5e1998bd177e93a" +
+					"7363c344fe6b199ee5d02e82d522c4fe" +
+					"ba15452f80288a821a579116ec6dad2b" +
+					"3b310da903401aa62100ab5d1a36553e" +
+					"06203b33890cc9b832f79ef80560ccb9" +
+					"a39ce767967ed628c6ad573cb116dbef" +
+					"efd75499da96bd68a8a97b928a8bbc10" +
+					"3b6621fcde2beca1231d206be6cd9ec7" +
+					"aff6f6c94fcd7204ed3455c68c83f4a4" +
+					"1da4af2b74ef5c53f1d8ac70bdcb7ed1" +
+					"85ce81bd84359d44254d95629e9855a9" +
+					"4a7c1958d1f8ada5d0532ed8a5aa3fb2" +
+					"d17ba70eb6248e594e1a2297acbbb39d" +
+					"502f1a8c6eb6f1ce22b3de1a1f40cc24" +
+					"554119a831a9aad6079cad88425de6bd" +
+					"e1a9187ebb6092cf67bf2b13fd65f270" +
+					"88d78b7e883c8759d2c4f5c65adb7553" +
+					"878ad575f9fad878e80a0c9ba63bcbcc" +
+					"2732e69485bbc9c90bfbd62481d9089b" +
+					"eccf80cfe2df16a2cf65bd92dd597b07" +
+					"07e0917af48bbb75fed413d238f5555a" +
+					"7a569d80c3414a8d0859dc65a46128ba" +
+					"b27af87a71314f318c782b23ebfe808b" +
+					"82b0ce26401d2e22f04d83d1255dc51a" +
+					"ddd3b75a2b1ae0784504df543af8969b" +
+					"e3ea7082ff7fc9888c144da2af58429e" +
+					"c96031dbcad3dad9af0dcbaaaf268cb8" +
+					"fcffead94f3c7ca495e056a9b47acdb7" +
+					"51fb73e666c6c655ade8297297d07ad1" +
+					"ba5e43f1bca32301651339e22904cc8c" +
+					"42f58c30c04aafdb038dda0847dd988d" +
+					"cda6f3bfd15c4b4c4525004aa06eeff8" +
+					"ca61783aacec57fb3d1f92b0fe2fd1a8" +
+					"5f6724517b65e614ad6808d6f6ee34df" +
+					"f7310fdc82aebfd904b01e1dc54b2927" +
+					"094b2db68d6f903b68401adebf5a7e08" +
+					"d78ff4ef5d63653a65040cf9bfd4aca7" +
+					"984a74d37145986780fc0b16ac451649" +
+					"de6188a7dbdf191f64b5fc5e2ab47b57" +
+					"f7f7276cd419c17a3ca8e1b939ae49e4" +
+					"88acba6b965610b5480109c8b17b80e1" +
+					"b7b750dfc7598d5d5011fd2dcc5600a3" +
+					"2ef5b52a1ecc820e308aa342721aac09" +
+					"43bf6686b64b2579376504ccc493d97e" +
+					"6aed3fb0f9cd71a43dd497f01f17c0e2" +
+					"cb3797aa2a2f256656168e6c496afc5f" +
+					"b93246f6b1116398a346f1a641f3b041" +
+					"e989f7914f90cc2c7fff357876e506b5" +
+					"0d334ba77c225bc307ba537152f3f161" +
+					"0e4eafe595f6d9d90d11faa933a15ef1" +
+					"369546868a7f3a45a96768d40fd9d034" +
+					"12c091c6315cf4fde7cb68606937380d" +
+					"b2eaaa707b4c4185c32eddcdd306705e" +
+					"4dc1ffc872eeee475a64dfac86aba41c" +
+					"0618983f8741c5ef68d3a101e8a3b8ca" +
+					"c60c905c15fc910840b94c00a0b9d0",
+			"0aab4c900501b3e24d7cdf4663326a3a" +
+					"87df5e4843b2cbdb67cbf6e460fec350" +
+					"aa5371b1508f9f4528ecea23c436d94b" +
+					"5e8fcd4f681e30a6ac00a9704a188a03"
+	}, {
+			"833fe62409237b9d62ec77587520911e" +
+					"9a759cec1d19755b7da901b96dca3d42",
+			"ec172b93ad5e563bf4932c70e1245034" +
+					"c35467ef2efd4d64ebf819683467e2bf",
+			"ddaf35a193617abacc417349ae204131" +
+					"12e6fa4e89a97ea20a9eeee64b55d39a" +
+					"2192992a274fc1a836ba3c23a3feebbd" +
+					"454d4423643ce80e2a9ac94fa54ca49f",
+			"dc2a4459e7369633a52b1bf277839a00" +
+					"201009a3efbf3ecb69bea2186c26b589" +
+					"09351fc9ac90b3ecfdfbc7c66431e030" +
+					"3dca179c138ac17ad9bef1177331a704"
+	}};
+
+	@Override
+	protected KeyPair generateKeyPair() {
+		return crypto.generateSignatureKeyPair();
+	}
+
+	@Override
+	protected byte[] sign(String label, byte[] toSign, byte[] privateKey)
+			throws GeneralSecurityException {
+		return crypto.sign(label, toSign, privateKey);
+	}
+
+	@Override
+	protected boolean verify(String label, byte[] signedData, byte[] publicKey,
+			byte[] signature) throws GeneralSecurityException {
+		return crypto.verify(label, signedData, publicKey, signature);
+	}
+
+	@Test
+	public void testRfc8032TestVectors() throws Exception {
+		for (String[] vector : TEST_VECTORS) {
+			byte[] privateKeyBytes = fromHexString(vector[0]);
+			byte[] publicKeyBytes = fromHexString(vector[1]);
+			byte[] messageBytes = fromHexString(vector[2]);
+			byte[] signatureBytes = fromHexString(vector[3]);
+
+			EdSignature signature = new EdSignature();
+			signature.initSign(new EdPrivateKey(privateKeyBytes));
+			signature.update(messageBytes);
+			assertArrayEquals(signatureBytes, signature.sign());
+
+			signature.initVerify(new EdPublicKey(publicKeyBytes));
+			signature.update(messageBytes);
+			assertTrue(signature.verify(signatureBytes));
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/crypto/EllipticCurveMultiplicationTest.java

@@ -13,11 +13,11 @@ import org.spongycastle.crypto.params.ECPrivateKeyParameters;
 import org.spongycastle.crypto.params.ECPublicKeyParameters;
 import org.spongycastle.math.ec.ECCurve;
 import org.spongycastle.math.ec.ECPoint;
+import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
 
 import java.math.BigInteger;
 import java.security.SecureRandom;
 
-import static org.briarproject.bramble.crypto.EllipticCurveConstants.PARAMETERS;
 import static org.junit.Assert.assertEquals;
 
 public class EllipticCurveMultiplicationTest extends BrambleTestCase {
@@ -31,15 +31,11 @@ public class EllipticCurveMultiplicationTest extends BrambleTestCase {
 		ECPoint defaultG = defaultX9Parameters.getG();
 		BigInteger defaultN = defaultX9Parameters.getN();
 		BigInteger defaultH = defaultX9Parameters.getH();
-		// Check that the default parameters are equal to our parameters
-		assertEquals(PARAMETERS.getCurve(), defaultCurve);
-		assertEquals(PARAMETERS.getG(), defaultG);
-		assertEquals(PARAMETERS.getN(), defaultN);
-		assertEquals(PARAMETERS.getH(), defaultH);
-		// ECDomainParameters doesn't have an equals() method, but it's just a
-		// container for the parameters
 		ECDomainParameters defaultParameters = new ECDomainParameters(
 				defaultCurve, defaultG, defaultN, defaultH);
+		// Instantiate an implementation using the Montgomery ladder multiplier
+		ECDomainParameters montgomeryParameters =
+				constantTime(defaultParameters);
 		// Generate two key pairs with each set of parameters, using the same
 		// deterministic PRNG for both sets of parameters
 		byte[] seed = new byte[32];
@@ -47,7 +43,7 @@ public class EllipticCurveMultiplicationTest extends BrambleTestCase {
 		// Montgomery ladder multiplier
 		SecureRandom random = new PseudoSecureRandom(seed);
 		ECKeyGenerationParameters montgomeryGeneratorParams =
-				new ECKeyGenerationParameters(PARAMETERS, random);
+				new ECKeyGenerationParameters(montgomeryParameters, random);
 		ECKeyPairGenerator montgomeryGenerator = new ECKeyPairGenerator();
 		montgomeryGenerator.init(montgomeryGeneratorParams);
 		AsymmetricCipherKeyPair montgomeryKeyPair1 =
@@ -107,4 +103,13 @@ public class EllipticCurveMultiplicationTest extends BrambleTestCase {
 		assertEquals(sharedSecretMontgomeryMontgomery,
 				sharedSecretDefaultDefault);
 	}
+
+	private static ECDomainParameters constantTime(ECDomainParameters in) {
+		ECCurve curve = in.getCurve().configure().setMultiplier(
+				new MontgomeryLadderMultiplier()).create();
+		BigInteger x = in.getG().getAffineXCoord().toBigInteger();
+		BigInteger y = in.getG().getAffineYCoord().toBigInteger();
+		ECPoint g = curve.createPoint(x, y);
+		return new ECDomainParameters(curve, g, in.getN(), in.getH());
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/crypto/EllipticCurvePerformanceTest.java

@@ -1,16 +1,20 @@
 package org.briarproject.bramble.crypto;
 
+import net.i2p.crypto.eddsa.EdDSASecurityProvider;
+import net.i2p.crypto.eddsa.KeyPairGenerator;
+
 import org.spongycastle.asn1.sec.SECNamedCurves;
 import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
 import org.spongycastle.asn1.x9.X9ECParameters;
 import org.spongycastle.crypto.AsymmetricCipherKeyPair;
+import org.spongycastle.crypto.BasicAgreement;
 import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.agreement.ECDHBasicAgreement;
 import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
+import org.spongycastle.crypto.digests.Blake2bDigest;
 import org.spongycastle.crypto.generators.ECKeyPairGenerator;
 import org.spongycastle.crypto.params.ECDomainParameters;
 import org.spongycastle.crypto.params.ECKeyGenerationParameters;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
 import org.spongycastle.crypto.params.ParametersWithRandom;
 import org.spongycastle.crypto.signers.DSADigestSigner;
 import org.spongycastle.crypto.signers.DSAKCalculator;
@@ -19,14 +23,22 @@ import org.spongycastle.crypto.signers.HMacDSAKCalculator;
 import org.spongycastle.math.ec.ECCurve;
 import org.spongycastle.math.ec.ECPoint;
 import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
+import org.whispersystems.curve25519.Curve25519;
+import org.whispersystems.curve25519.Curve25519KeyPair;
 
 import java.math.BigInteger;
+import java.security.GeneralSecurityException;
+import java.security.KeyPair;
+import java.security.Provider;
 import java.security.SecureRandom;
+import java.security.Signature;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
+import static net.i2p.crypto.eddsa.EdDSAEngine.SIGNATURE_ALGORITHM;
+
 // Not a JUnit test
 public class EllipticCurvePerformanceTest {
 
@@ -37,8 +49,9 @@ public class EllipticCurvePerformanceTest {
 			"secp256k1", "secp256r1", "secp384r1", "secp521r1");
 	private static final List<String> BRAINPOOL_NAMES = Arrays.asList(
 			"brainpoolp256r1", "brainpoolp384r1", "brainpoolp512r1");
+	private static final Provider ED_PROVIDER = new EdDSASecurityProvider();
 
-	public static void main(String[] args) {
+	public static void main(String[] args) throws GeneralSecurityException {
 		for (String name : SEC_NAMES) {
 			ECDomainParameters params =
 					convertParams(SECNamedCurves.getByName(name));
@@ -51,43 +64,31 @@ public class EllipticCurvePerformanceTest {
 			runTest(name + " default", params);
 			runTest(name + " constant", constantTime(params));
 		}
-		runTest("ours", EllipticCurveConstants.PARAMETERS);
+		runCurve25519Test();
+		runEd25519Test();
 	}
 
 	private static void runTest(String name, ECDomainParameters params) {
 		// Generate two key pairs using the given parameters
-		ECKeyGenerationParameters generatorParams =
-				new ECKeyGenerationParameters(params, random);
 		ECKeyPairGenerator generator = new ECKeyPairGenerator();
-		generator.init(generatorParams);
+		generator.init(new ECKeyGenerationParameters(params, random));
 		AsymmetricCipherKeyPair keyPair1 = generator.generateKeyPair();
-		ECPublicKeyParameters public1 =
-				(ECPublicKeyParameters) keyPair1.getPublic();
-		ECPrivateKeyParameters private1 =
-				(ECPrivateKeyParameters) keyPair1.getPrivate();
 		AsymmetricCipherKeyPair keyPair2 = generator.generateKeyPair();
-		ECPublicKeyParameters public2 =
-				(ECPublicKeyParameters) keyPair2.getPublic();
-		// Time some ECDH key agreements
-		List<Long> samples = new ArrayList<>();
-		for (int i = 0; i < SAMPLES; i++) {
-			ECDHCBasicAgreement agreement = new ECDHCBasicAgreement();
-			long start = System.nanoTime();
-			agreement.init(private1);
-			agreement.calculateAgreement(public2);
-			samples.add(System.nanoTime() - start);
-		}
-		long agreementMedian = median(samples);
+		// Time some ECDH and ECDHC key agreements
+		long agreementMedian = runAgreementTest(keyPair1, keyPair2, false);
+		long agreementWithCofactorMedian =
+				runAgreementTest(keyPair1, keyPair2, true);
 		// Time some signatures
+		List<Long> samples = new ArrayList<>();
 		List<byte[]> signatures = new ArrayList<>();
-		samples.clear();
 		for (int i = 0; i < SAMPLES; i++) {
-			Digest digest = new Blake2sDigest();
+			Digest digest = new Blake2bDigest(256);
 			DSAKCalculator calculator = new HMacDSAKCalculator(digest);
 			DSADigestSigner signer = new DSADigestSigner(new ECDSASigner(
 					calculator), digest);
 			long start = System.nanoTime();
-			signer.init(true, new ParametersWithRandom(private1, random));
+			signer.init(true,
+					new ParametersWithRandom(keyPair1.getPrivate(), random));
 			signer.update(new byte[BYTES_TO_SIGN], 0, BYTES_TO_SIGN);
 			signatures.add(signer.generateSignature());
 			samples.add(System.nanoTime() - start);
@@ -96,22 +97,88 @@ public class EllipticCurvePerformanceTest {
 		// Time some signature verifications
 		samples.clear();
 		for (int i = 0; i < SAMPLES; i++) {
-			Digest digest = new Blake2sDigest();
+			Digest digest = new Blake2bDigest(256);
 			DSAKCalculator calculator = new HMacDSAKCalculator(digest);
 			DSADigestSigner signer = new DSADigestSigner(new ECDSASigner(
 					calculator), digest);
 			long start = System.nanoTime();
-			signer.init(false, public1);
+			signer.init(false, keyPair1.getPublic());
 			signer.update(new byte[BYTES_TO_SIGN], 0, BYTES_TO_SIGN);
 			if (!signer.verifySignature(signatures.get(i)))
 				throw new AssertionError();
 			samples.add(System.nanoTime() - start);
 		}
 		long verificationMedian = median(samples);
-		System.out.println(name + ": "
-				+ agreementMedian + " "
-				+ signatureMedian + " "
-				+ verificationMedian);
+		System.out.println(String.format("%s: %,d %,d %,d %,d", name,
+				agreementMedian, agreementWithCofactorMedian,
+				signatureMedian, verificationMedian));
+	}
+
+	private static long runAgreementTest(AsymmetricCipherKeyPair keyPair1,
+			AsymmetricCipherKeyPair keyPair2, boolean withCofactor) {
+		List<Long> samples = new ArrayList<>();
+		for (int i = 0; i < SAMPLES; i++) {
+			BasicAgreement agreement = createAgreement(withCofactor);
+			long start = System.nanoTime();
+			agreement.init(keyPair1.getPrivate());
+			agreement.calculateAgreement(keyPair2.getPublic());
+			samples.add(System.nanoTime() - start);
+		}
+		return median(samples);
+	}
+
+	private static BasicAgreement createAgreement(boolean withCofactor) {
+		if (withCofactor) return new ECDHCBasicAgreement();
+		else return new ECDHBasicAgreement();
+	}
+
+	private static void runCurve25519Test() {
+		Curve25519 curve25519 = Curve25519.getInstance("java");
+		Curve25519KeyPair keyPair1 = curve25519.generateKeyPair();
+		Curve25519KeyPair keyPair2 = curve25519.generateKeyPair();
+		// Time some key agreements
+		List<Long> samples = new ArrayList<>();
+		for (int i = 0; i < SAMPLES; i++) {
+			long start = System.nanoTime();
+			curve25519.calculateAgreement(keyPair1.getPublicKey(),
+					keyPair2.getPrivateKey());
+			samples.add(System.nanoTime() - start);
+		}
+		long agreementMedian = median(samples);
+		System.out.println(String.format("Curve25519: %,d - - -",
+				agreementMedian));
+	}
+
+	private static void runEd25519Test() throws GeneralSecurityException {
+		KeyPair keyPair = new KeyPairGenerator().generateKeyPair();
+		// Time some signatures
+		List<Long> samples = new ArrayList<>();
+		List<byte[]> signatures = new ArrayList<>();
+		for (int i = 0; i < SAMPLES; i++) {
+			Signature signature =
+					Signature.getInstance(SIGNATURE_ALGORITHM, ED_PROVIDER);
+			long start = System.nanoTime();
+			signature.initSign(keyPair.getPrivate(), random);
+			signature.update(new byte[BYTES_TO_SIGN], 0, BYTES_TO_SIGN);
+			signatures.add(signature.sign());
+			samples.add(System.nanoTime() - start);
+		}
+		long signatureMedian = median(samples);
+		// Time some signature verifications
+		samples.clear();
+		for (int i = 0; i < SAMPLES; i++) {
+			Signature signature =
+					Signature.getInstance(SIGNATURE_ALGORITHM, ED_PROVIDER);
+			long start = System.nanoTime();
+			signature.initVerify(keyPair.getPublic());
+			signature.update(new byte[BYTES_TO_SIGN], 0, BYTES_TO_SIGN);
+			if (!signature.verify(signatures.get(i)))
+				throw new AssertionError();
+			samples.add(System.nanoTime() - start);
+		}
+		long verificationMedian = median(samples);
+		System.out.println(String.format("Ed25519: - - %,d %,d",
+				signatureMedian, verificationMedian));
 	}
 
 	private static long median(List<Long> list) {

bramble-core/src/test/java/org/briarproject/bramble/crypto/HashTest.java

@@ -22,7 +22,7 @@ public class HashTest extends BrambleTestCase {
 	private final byte[] inputBytes2 = new byte[0];
 
 	public HashTest() {
-		crypto = new CryptoComponentImpl(new TestSecureRandomProvider());
+		crypto = new CryptoComponentImpl(new TestSecureRandomProvider(), null);
 	}
 
 	@Test

bramble-core/src/test/java/org/briarproject/bramble/crypto/KeyAgreementTest.java

@@ -2,41 +2,80 @@ package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyPair;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.system.SecureRandomProvider;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
 import org.junit.Test;
+import org.whispersystems.curve25519.Curve25519;
 
+import java.security.GeneralSecurityException;
+import java.util.Random;
+
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.SHARED_SECRET_LABEL;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.util.StringUtils.fromHexString;
 import static org.junit.Assert.assertArrayEquals;
 
 public class KeyAgreementTest extends BrambleTestCase {
 
-	@Test
-	public void testDeriveMasterSecret() throws Exception {
-		SecureRandomProvider
-				secureRandomProvider = new TestSecureRandomProvider();
-		CryptoComponent crypto = new CryptoComponentImpl(secureRandomProvider);
-		KeyPair aPair = crypto.generateAgreementKeyPair();
-		byte[] aPub = aPair.getPublic().getEncoded();
-		KeyPair bPair = crypto.generateAgreementKeyPair();
-		byte[] bPub = bPair.getPublic().getEncoded();
-		SecretKey aMaster = crypto.deriveMasterSecret(aPub, bPair, true);
-		SecretKey bMaster = crypto.deriveMasterSecret(bPub, aPair, false);
-		assertArrayEquals(aMaster.getBytes(), bMaster.getBytes());
+	// Test vector from RFC 7748: Alice's private and public keys, Bob's
+	// private and public keys, and the shared secret
+	// https://tools.ietf.org/html/rfc7748#section-6.1
+	private static final String ALICE_PRIVATE =
+			"77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a";
+	private static final String ALICE_PUBLIC =
+			"8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a";
+	private static final String BOB_PRIVATE =
+			"5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb";
+	private static final String BOB_PUBLIC =
+			"de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f";
+	private static final String SHARED_SECRET =
+			"4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742";
+
+	private final CryptoComponent crypto =
+			new CryptoComponentImpl(new TestSecureRandomProvider(), null);
+	private final byte[][] inputs;
+
+	public KeyAgreementTest() {
+		Random random = new Random();
+		inputs = new byte[random.nextInt(10) + 1][];
+		for (int i = 0; i < inputs.length; i++)
+			inputs[i] = getRandomBytes(random.nextInt(256));
 	}
 
 	@Test
-	public void testDeriveSharedSecret() throws Exception {
-		SecureRandomProvider
-				secureRandomProvider = new TestSecureRandomProvider();
-		CryptoComponent crypto = new CryptoComponentImpl(secureRandomProvider);
+	public void testDerivesSharedSecret() throws Exception {
 		KeyPair aPair = crypto.generateAgreementKeyPair();
-		byte[] aPub = aPair.getPublic().getEncoded();
 		KeyPair bPair = crypto.generateAgreementKeyPair();
-		byte[] bPub = bPair.getPublic().getEncoded();
-		SecretKey aShared = crypto.deriveSharedSecret(bPub, aPair, true);
-		SecretKey bShared = crypto.deriveSharedSecret(aPub, bPair, false);
+		SecretKey aShared = crypto.deriveSharedSecret(SHARED_SECRET_LABEL,
+				bPair.getPublic(), aPair, inputs);
+		SecretKey bShared = crypto.deriveSharedSecret(SHARED_SECRET_LABEL,
+				aPair.getPublic(), bPair, inputs);
 		assertArrayEquals(aShared.getBytes(), bShared.getBytes());
 	}
+
+	@Test(expected = GeneralSecurityException.class)
+	public void testRejectsInvalidPublicKey() throws Exception {
+		KeyPair keyPair = crypto.generateAgreementKeyPair();
+		PublicKey invalid = new Curve25519PublicKey(new byte[32]);
+		crypto.deriveSharedSecret(SHARED_SECRET_LABEL, invalid, keyPair,
+				inputs);
+	}
+
+	@Test
+	public void testRfc7748TestVector() throws Exception {
+		// Private keys need to be clamped because curve25519-java does the
+		// clamping at key generation time, not multiplication time
+		byte[] aPriv = Curve25519KeyParser.clamp(fromHexString(ALICE_PRIVATE));
+		byte[] aPub = fromHexString(ALICE_PUBLIC);
+		byte[] bPriv = Curve25519KeyParser.clamp(fromHexString(BOB_PRIVATE));
+		byte[] bPub = fromHexString(BOB_PUBLIC);
+		byte[] sharedSecret = fromHexString(SHARED_SECRET);
+		Curve25519 curve25519 = Curve25519.getInstance("java");
+		assertArrayEquals(sharedSecret,
+				curve25519.calculateAgreement(aPub, bPriv));
+		assertArrayEquals(sharedSecret,
+				curve25519.calculateAgreement(bPub, aPriv));
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/crypto/KeyDerivationTest.java

@@ -3,11 +3,11 @@ package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
 import org.junit.Test;
 
 import java.util.ArrayList;
@@ -16,35 +16,34 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 public class KeyDerivationTest extends BrambleTestCase {
 
+	private final CryptoComponent crypto =
+			new CryptoComponentImpl(new TestSecureRandomProvider(), null);
+	private final TransportCrypto transportCrypto =
+			new TransportCryptoImpl(crypto);
 	private final TransportId transportId = new TransportId("id");
-	private final CryptoComponent crypto;
-	private final SecretKey master;
-
-	public KeyDerivationTest() {
-		crypto = new CryptoComponentImpl(new TestSecureRandomProvider());
-		master = TestUtils.getSecretKey();
-	}
+	private final SecretKey master = getSecretKey();
 
 	@Test
 	public void testKeysAreDistinct() {
-		TransportKeys k = crypto.deriveTransportKeys(transportId, master,
-				123, true);
+		TransportKeys k = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
 		assertAllDifferent(k);
 	}
 
 	@Test
 	public void testCurrentKeysMatchCurrentKeysOfContact() {
 		// Start in rotation period 123
-		TransportKeys kA = crypto.deriveTransportKeys(transportId, master,
-				123, true);
-		TransportKeys kB = crypto.deriveTransportKeys(transportId, master,
-				123, false);
+		TransportKeys kA = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
+		TransportKeys kB = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, false);
 		// Alice's incoming keys should equal Bob's outgoing keys
 		assertArrayEquals(kA.getCurrentIncomingKeys().getTagKey().getBytes(),
 				kB.getCurrentOutgoingKeys().getTagKey().getBytes());
@@ -56,8 +55,8 @@ public class KeyDerivationTest extends BrambleTestCase {
 		assertArrayEquals(kA.getCurrentOutgoingKeys().getHeaderKey().getBytes(),
 				kB.getCurrentIncomingKeys().getHeaderKey().getBytes());
 		// Rotate into the future
-		kA = crypto.rotateTransportKeys(kA, 456);
-		kB = crypto.rotateTransportKeys(kB, 456);
+		kA = transportCrypto.rotateTransportKeys(kA, 456);
+		kB = transportCrypto.rotateTransportKeys(kB, 456);
 		// Alice's incoming keys should equal Bob's outgoing keys
 		assertArrayEquals(kA.getCurrentIncomingKeys().getTagKey().getBytes(),
 				kB.getCurrentOutgoingKeys().getTagKey().getBytes());
@@ -73,22 +72,23 @@ public class KeyDerivationTest extends BrambleTestCase {
 	@Test
 	public void testPreviousKeysMatchPreviousKeysOfContact() {
 		// Start in rotation period 123
-		TransportKeys kA = crypto.deriveTransportKeys(transportId, master,
-				123, true);
-		TransportKeys kB = crypto.deriveTransportKeys(transportId, master,
-				123, false);
+		TransportKeys kA = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
+		TransportKeys kB = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, false);
 		// Compare Alice's previous keys in period 456 with Bob's current keys
 		// in period 455
-		kA = crypto.rotateTransportKeys(kA, 456);
-		kB = crypto.rotateTransportKeys(kB, 455);
+		kA = transportCrypto.rotateTransportKeys(kA, 456);
+		kB = transportCrypto.rotateTransportKeys(kB, 455);
 		// Alice's previous incoming keys should equal Bob's outgoing keys
 		assertArrayEquals(kA.getPreviousIncomingKeys().getTagKey().getBytes(),
 				kB.getCurrentOutgoingKeys().getTagKey().getBytes());
-		assertArrayEquals(kA.getPreviousIncomingKeys().getHeaderKey().getBytes(),
+		assertArrayEquals(
+				kA.getPreviousIncomingKeys().getHeaderKey().getBytes(),
 				kB.getCurrentOutgoingKeys().getHeaderKey().getBytes());
 		// Compare Alice's current keys in period 456 with Bob's previous keys
 		// in period 457
-		kB = crypto.rotateTransportKeys(kB, 457);
+		kB = transportCrypto.rotateTransportKeys(kB, 457);
 		// Alice's outgoing keys should equal Bob's previous incoming keys
 		assertArrayEquals(kA.getCurrentOutgoingKeys().getTagKey().getBytes(),
 				kB.getPreviousIncomingKeys().getTagKey().getBytes());
@@ -99,14 +99,14 @@ public class KeyDerivationTest extends BrambleTestCase {
 	@Test
 	public void testNextKeysMatchNextKeysOfContact() {
 		// Start in rotation period 123
-		TransportKeys kA = crypto.deriveTransportKeys(transportId, master,
-				123, true);
-		TransportKeys kB = crypto.deriveTransportKeys(transportId, master,
-				123, false);
+		TransportKeys kA = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
+		TransportKeys kB = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, false);
 		// Compare Alice's current keys in period 456 with Bob's next keys in
 		// period 455
-		kA = crypto.rotateTransportKeys(kA, 456);
-		kB = crypto.rotateTransportKeys(kB, 455);
+		kA = transportCrypto.rotateTransportKeys(kA, 456);
+		kB = transportCrypto.rotateTransportKeys(kB, 455);
 		// Alice's outgoing keys should equal Bob's next incoming keys
 		assertArrayEquals(kA.getCurrentOutgoingKeys().getTagKey().getBytes(),
 				kB.getNextIncomingKeys().getTagKey().getBytes());
@@ -114,7 +114,7 @@ public class KeyDerivationTest extends BrambleTestCase {
 				kB.getNextIncomingKeys().getHeaderKey().getBytes());
 		// Compare Alice's next keys in period 456 with Bob's current keys
 		// in period 457
-		kB = crypto.rotateTransportKeys(kB, 457);
+		kB = transportCrypto.rotateTransportKeys(kB, 457);
 		// Alice's next incoming keys should equal Bob's outgoing keys
 		assertArrayEquals(kA.getNextIncomingKeys().getTagKey().getBytes(),
 				kB.getCurrentOutgoingKeys().getTagKey().getBytes());
@@ -124,12 +124,12 @@ public class KeyDerivationTest extends BrambleTestCase {
 
 	@Test
 	public void testMasterKeyAffectsOutput() {
-		SecretKey master1 = TestUtils.getSecretKey();
+		SecretKey master1 = getSecretKey();
 		assertFalse(Arrays.equals(master.getBytes(), master1.getBytes()));
-		TransportKeys k = crypto.deriveTransportKeys(transportId, master,
-				123, true);
-		TransportKeys k1 = crypto.deriveTransportKeys(transportId, master1,
-				123, true);
+		TransportKeys k = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
+		TransportKeys k1 = transportCrypto.deriveTransportKeys(transportId,
+				master1, 123, true);
 		assertAllDifferent(k, k1);
 	}
 
@@ -137,10 +137,10 @@ public class KeyDerivationTest extends BrambleTestCase {
 	public void testTransportIdAffectsOutput() {
 		TransportId transportId1 = new TransportId("id1");
 		assertFalse(transportId.getString().equals(transportId1.getString()));
-		TransportKeys k = crypto.deriveTransportKeys(transportId, master,
-				123, true);
-		TransportKeys k1 = crypto.deriveTransportKeys(transportId1, master,
-				123, true);
+		TransportKeys k = transportCrypto.deriveTransportKeys(transportId,
+				master, 123, true);
+		TransportKeys k1 = transportCrypto.deriveTransportKeys(transportId1,
+				master, 123, true);
 		assertAllDifferent(k, k1);
 	}
 

bramble-core/src/test/java/org/briarproject/bramble/crypto/KeyEncodingAndParsingTest.java

@@ -6,29 +6,30 @@ import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
 import org.junit.Test;
 
 import java.security.GeneralSecurityException;
 
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_AGREEMENT_PUBLIC_KEY_BYTES;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_BYTES;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_PUBLIC_KEY_BYTES;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertTrue;
 
 public class KeyEncodingAndParsingTest extends BrambleTestCase {
 
 	private final CryptoComponentImpl crypto =
-			new CryptoComponentImpl(new TestSecureRandomProvider());
+			new CryptoComponentImpl(new TestSecureRandomProvider(), null);
 
 	@Test
 	public void testAgreementPublicKeyLength() throws Exception {
 		// Generate 10 agreement key pairs
 		for (int i = 0; i < 10; i++) {
-			KeyPair keyPair = crypto.generateSignatureKeyPair();
+			KeyPair keyPair = crypto.generateAgreementKeyPair();
 			// Check the length of the public key
 			byte[] publicKey = keyPair.getPublic().getEncoded();
-			assertTrue(publicKey.length <= MAX_PUBLIC_KEY_LENGTH);
+			assertTrue(publicKey.length <= MAX_AGREEMENT_PUBLIC_KEY_BYTES);
 		}
 	}
 
@@ -45,7 +46,8 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 		aPub = parser.parsePublicKey(aPub.getEncoded());
 		aPub = parser.parsePublicKey(aPub.getEncoded());
 		// Derive the shared secret again - it should be the same
-		byte[] secret1 = crypto.performRawKeyAgreement(bPair.getPrivate(), aPub);
+		byte[] secret1 =
+				crypto.performRawKeyAgreement(bPair.getPrivate(), aPub);
 		assertArrayEquals(secret, secret1);
 	}
 
@@ -62,7 +64,8 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 		bPriv = parser.parsePrivateKey(bPriv.getEncoded());
 		bPriv = parser.parsePrivateKey(bPriv.getEncoded());
 		// Derive the shared secret again - it should be the same
-		byte[] secret1 = crypto.performRawKeyAgreement(bPriv, aPair.getPublic());
+		byte[] secret1 =
+				crypto.performRawKeyAgreement(bPriv, aPair.getPublic());
 		assertArrayEquals(secret, secret1);
 	}
 
@@ -76,12 +79,12 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 		// Parse some random byte arrays - expect GeneralSecurityException
 		for (int i = 0; i < 1000; i++) {
 			try {
-				parser.parsePublicKey(TestUtils.getRandomBytes(pubLength));
+				parser.parsePublicKey(getRandomBytes(pubLength));
 			} catch (GeneralSecurityException expected) {
 				// Expected
 			}
 			try {
-				parser.parsePrivateKey(TestUtils.getRandomBytes(privLength));
+				parser.parsePrivateKey(getRandomBytes(privLength));
 			} catch (GeneralSecurityException expected) {
 				// Expected
 			}
@@ -95,7 +98,7 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 			KeyPair keyPair = crypto.generateSignatureKeyPair();
 			// Check the length of the public key
 			byte[] publicKey = keyPair.getPublic().getEncoded();
-			assertTrue(publicKey.length <= MAX_PUBLIC_KEY_LENGTH);
+			assertTrue(publicKey.length <= MAX_SIGNATURE_PUBLIC_KEY_BYTES);
 		}
 	}
 
@@ -106,44 +109,53 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 			KeyPair keyPair = crypto.generateSignatureKeyPair();
 			byte[] key = keyPair.getPrivate().getEncoded();
 			// Sign some random data and check the length of the signature
-			byte[] toBeSigned = TestUtils.getRandomBytes(1234);
+			byte[] toBeSigned = getRandomBytes(1234);
 			byte[] signature = crypto.sign("label", toBeSigned, key);
-			assertTrue(signature.length <= MAX_SIGNATURE_LENGTH);
+			assertTrue(signature.length <= MAX_SIGNATURE_BYTES);
 		}
 	}
 
 	@Test
 	public void testSignaturePublicKeyEncodingAndParsing() throws Exception {
 		KeyParser parser = crypto.getSignatureKeyParser();
-		// Generate two key pairs
-		KeyPair aPair = crypto.generateSignatureKeyPair();
-		KeyPair bPair = crypto.generateSignatureKeyPair();
-		// Derive the shared secret
-		PublicKey aPub = aPair.getPublic();
-		byte[] secret = crypto.performRawKeyAgreement(bPair.getPrivate(), aPub);
+		// Generate a key pair and sign some data
+		KeyPair keyPair = crypto.generateSignatureKeyPair();
+		PublicKey publicKey = keyPair.getPublic();
+		PrivateKey privateKey = keyPair.getPrivate();
+		byte[] message = getRandomBytes(123);
+		byte[] signature = crypto.sign("test", message,
+				privateKey.getEncoded());
+		// Verify the signature
+		assertTrue(crypto.verify("test", message, publicKey.getEncoded(),
+				signature));
 		// Encode and parse the public key - no exceptions should be thrown
-		aPub = parser.parsePublicKey(aPub.getEncoded());
-		aPub = parser.parsePublicKey(aPub.getEncoded());
-		// Derive the shared secret again - it should be the same
-		byte[] secret1 = crypto.performRawKeyAgreement(bPair.getPrivate(), aPub);
-		assertArrayEquals(secret, secret1);
+		publicKey = parser.parsePublicKey(publicKey.getEncoded());
+		// Verify the signature again
+		assertTrue(crypto.verify("test", message, publicKey.getEncoded(),
+				signature));
 	}
 
 	@Test
 	public void testSignaturePrivateKeyEncodingAndParsing() throws Exception {
 		KeyParser parser = crypto.getSignatureKeyParser();
-		// Generate two key pairs
-		KeyPair aPair = crypto.generateSignatureKeyPair();
-		KeyPair bPair = crypto.generateSignatureKeyPair();
-		// Derive the shared secret
-		PrivateKey bPriv = bPair.getPrivate();
-		byte[] secret = crypto.performRawKeyAgreement(bPriv, aPair.getPublic());
+		// Generate a key pair and sign some data
+		KeyPair keyPair = crypto.generateSignatureKeyPair();
+		PublicKey publicKey = keyPair.getPublic();
+		PrivateKey privateKey = keyPair.getPrivate();
+		byte[] message = getRandomBytes(123);
+		byte[] signature = crypto.sign("test", message,
+				privateKey.getEncoded());
+		// Verify the signature
+		assertTrue(crypto.verify("test", message, publicKey.getEncoded(),
+				signature));
 		// Encode and parse the private key - no exceptions should be thrown
-		bPriv = parser.parsePrivateKey(bPriv.getEncoded());
-		bPriv = parser.parsePrivateKey(bPriv.getEncoded());
-		// Derive the shared secret again - it should be the same
-		byte[] secret1 = crypto.performRawKeyAgreement(bPriv, aPair.getPublic());
-		assertArrayEquals(secret, secret1);
+		privateKey = parser.parsePrivateKey(privateKey.getEncoded());
+		// Sign the data again - the signatures should be the same
+		byte[] signature1 = crypto.sign("test", message,
+				privateKey.getEncoded());
+		assertTrue(crypto.verify("test", message, publicKey.getEncoded(),
+				signature1));
+		assertArrayEquals(signature, signature1);
 	}
 
 	@Test
@@ -156,12 +168,12 @@ public class KeyEncodingAndParsingTest extends BrambleTestCase {
 		// Parse some random byte arrays - expect GeneralSecurityException
 		for (int i = 0; i < 1000; i++) {
 			try {
-				parser.parsePublicKey(TestUtils.getRandomBytes(pubLength));
+				parser.parsePublicKey(getRandomBytes(pubLength));
 			} catch (GeneralSecurityException expected) {
 				// Expected
 			}
 			try {
-				parser.parsePrivateKey(TestUtils.getRandomBytes(privLength));
+				parser.parsePrivateKey(getRandomBytes(privLength));
 			} catch (GeneralSecurityException expected) {
 				// Expected
 			}

bramble-core/src/test/java/org/briarproject/bramble/crypto/MacTest.java

@@ -4,42 +4,49 @@ import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
 import org.junit.Test;
 
 import java.util.Arrays;
 
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertFalse;
 
 public class MacTest extends BrambleTestCase {
 
-	private final CryptoComponent crypto;
+	private final CryptoComponent crypto =
+			new CryptoComponentImpl(new TestSecureRandomProvider(), null);
 
-	private final SecretKey k = TestUtils.getSecretKey();
-	private final byte[] inputBytes = TestUtils.getRandomBytes(123);
-	private final byte[] inputBytes1 = TestUtils.getRandomBytes(234);
-	private final byte[] inputBytes2 = new byte[0];
-
-	public MacTest() {
-		crypto = new CryptoComponentImpl(new TestSecureRandomProvider());
-	}
+	private final SecretKey key1 = getSecretKey(), key2 = getSecretKey();
+	private final String label1 = getRandomString(123);
+	private final String label2 = getRandomString(123);
+	private final byte[] input1 = getRandomBytes(123);
+	private final byte[] input2 = getRandomBytes(234);
+	private final byte[] input3 = new byte[0];
 
 	@Test
 	public void testIdenticalKeysAndInputsProduceIdenticalMacs() {
 		// Calculate the MAC twice - the results should be identical
-		byte[] mac = crypto.mac(k, inputBytes, inputBytes1, inputBytes2);
-		byte[] mac1 = crypto.mac(k, inputBytes, inputBytes1, inputBytes2);
+		byte[] mac = crypto.mac(label1, key1, input1, input2, input3);
+		byte[] mac1 = crypto.mac(label1, key1, input1, input2, input3);
 		assertArrayEquals(mac, mac1);
 	}
 
+	@Test
+	public void testDifferentLabelsProduceDifferentMacs() {
+		// Calculate the MAC with each label - the results should be different
+		byte[] mac = crypto.mac(label1, key1, input1, input2, input3);
+		byte[] mac1 = crypto.mac(label2, key1, input1, input2, input3);
+		assertFalse(Arrays.equals(mac, mac1));
+	}
+
 	@Test
 	public void testDifferentKeysProduceDifferentMacs() {
-		// Generate second random key
-		SecretKey k1 = TestUtils.getSecretKey();
 		// Calculate the MAC with each key - the results should be different
-		byte[] mac = crypto.mac(k, inputBytes, inputBytes1, inputBytes2);
-		byte[] mac1 = crypto.mac(k1, inputBytes, inputBytes1, inputBytes2);
+		byte[] mac = crypto.mac(label1, key1, input1, input2, input3);
+		byte[] mac1 = crypto.mac(label1, key2, input1, input2, input3);
 		assertFalse(Arrays.equals(mac, mac1));
 	}
 
@@ -47,8 +54,8 @@ public class MacTest extends BrambleTestCase {
 	public void testDifferentInputsProduceDifferentMacs() {
 		// Calculate the MAC with the inputs in different orders - the results
 		// should be different
-		byte[] mac = crypto.mac(k, inputBytes, inputBytes1, inputBytes2);
-		byte[] mac1 = crypto.mac(k, inputBytes2, inputBytes1, inputBytes);
+		byte[] mac = crypto.mac(label1, key1, input1, input2, input3);
+		byte[] mac1 = crypto.mac(label1, key1, input3, input2, input1);
 		assertFalse(Arrays.equals(mac, mac1));
 	}
 

bramble-core/src/test/java/org/briarproject/bramble/crypto/PasswordBasedEncryptionTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.system.SystemClock;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
 import org.briarproject.bramble.test.TestUtils;
@@ -8,14 +9,13 @@ import org.junit.Test;
 import java.util.Random;
 
 import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
 
-public class PasswordBasedKdfTest extends BrambleTestCase {
+public class PasswordBasedEncryptionTest extends BrambleTestCase {
 
 	private final CryptoComponentImpl crypto =
-			new CryptoComponentImpl(new TestSecureRandomProvider());
+			new CryptoComponentImpl(new TestSecureRandomProvider(),
+					new ScryptKdf(new SystemClock()));
 
 	@Test
 	public void testEncryptionAndDecryption() {
@@ -37,17 +37,4 @@ public class PasswordBasedKdfTest extends BrambleTestCase {
 		byte[] output = crypto.decryptWithPassword(ciphertext, password);
 		assertNull(output);
 	}
-
-	@Test
-	public void testCalibration() {
-		// If the target time is unachievable, one iteration should be used
-		int iterations = crypto.chooseIterationCount(0);
-		assertEquals(1, iterations);
-		// If the target time is long, more than one iteration should be used
-		iterations = crypto.chooseIterationCount(10 * 1000);
-		assertTrue(iterations > 1);
-		// If the target time is very long, max iterations should be used
-		iterations = crypto.chooseIterationCount(Integer.MAX_VALUE);
-		assertEquals(Integer.MAX_VALUE, iterations);
-	}
 }

bramble-core/src/test/java/org/briarproject/bramble/crypto/PseudoRandom.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.digests.Blake2bDigest;
 import org.spongycastle.crypto.engines.Salsa20Engine;
 import org.spongycastle.crypto.params.KeyParameter;
 import org.spongycastle.crypto.params.ParametersWithIV;
@@ -17,7 +18,7 @@ class PseudoRandom {
 	PseudoRandom(byte[] seed) {
 		// Hash the seed to produce a 32-byte key
 		byte[] key = new byte[32];
-		Digest digest = new Blake2sDigest();
+		Digest digest = new Blake2bDigest(256);
 		digest.update(seed, 0, seed.length);
 		digest.doFinal(key, 0);
 		// Initialise the stream cipher with an all-zero nonce

bramble-core/src/test/java/org/briarproject/bramble/crypto/ScryptKdfTest.java

@@ -0,0 +1,97 @@
+package org.briarproject.bramble.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.system.SystemClock;
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.junit.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import static junit.framework.TestCase.assertTrue;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
+import static org.junit.Assert.assertEquals;
+
+public class ScryptKdfTest extends BrambleTestCase {
+
+	@Test
+	public void testPasswordAffectsKey() throws Exception {
+		PasswordBasedKdf kdf = new ScryptKdf(new SystemClock());
+		byte[] salt = getRandomBytes(32);
+		Set<Bytes> keys = new HashSet<>();
+		for (int i = 0; i < 100; i++) {
+			String password = getRandomString(16);
+			SecretKey key = kdf.deriveKey(password, salt, 256);
+			assertTrue(keys.add(new Bytes(key.getBytes())));
+		}
+	}
+
+	@Test
+	public void testSaltAffectsKey() throws Exception {
+		PasswordBasedKdf kdf = new ScryptKdf(new SystemClock());
+		String password = getRandomString(16);
+		Set<Bytes> keys = new HashSet<>();
+		for (int i = 0; i < 100; i++) {
+			byte[] salt = getRandomBytes(32);
+			SecretKey key = kdf.deriveKey(password, salt, 256);
+			assertTrue(keys.add(new Bytes(key.getBytes())));
+		}
+	}
+
+	@Test
+	public void testCostParameterAffectsKey() throws Exception {
+		PasswordBasedKdf kdf = new ScryptKdf(new SystemClock());
+		String password = getRandomString(16);
+		byte[] salt = getRandomBytes(32);
+		Set<Bytes> keys = new HashSet<>();
+		for (int cost = 2; cost <= 256; cost *= 2) {
+			SecretKey key = kdf.deriveKey(password, salt, cost);
+			assertTrue(keys.add(new Bytes(key.getBytes())));
+		}
+	}
+
+	@Test
+	public void testCalibration() throws Exception {
+		Clock clock = new ArrayClock(
+				0, 50, // Duration for cost 256
+				0, 100, // Duration for cost 512
+				0, 200, // Duration for cost 1024
+				0, 400, // Duration for cost 2048
+				0, 800 // Duration for cost 4096
+		);
+		PasswordBasedKdf kdf = new ScryptKdf(clock);
+		assertEquals(4096, kdf.chooseCostParameter());
+	}
+
+	@Test
+	public void testCalibrationChoosesMinCost() throws Exception {
+		Clock clock = new ArrayClock(
+				0, 2000 // Duration for cost 256 is already too high
+		);
+		PasswordBasedKdf kdf = new ScryptKdf(clock);
+		assertEquals(256, kdf.chooseCostParameter());
+	}
+
+	private static class ArrayClock implements Clock {
+
+		private final long[] times;
+		private int index = 0;
+
+		private ArrayClock(long... times) {
+			this.times = times;
+		}
+
+		@Override
+		public long currentTimeMillis() {
+			return times[index++];
+		}
+
+		@Override
+		public void sleep(long milliseconds) throws InterruptedException {
+			Thread.sleep(milliseconds);
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/crypto/SignatureTest.java

@@ -8,23 +8,32 @@ import org.briarproject.bramble.test.TestUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.junit.Test;
 
+import java.security.GeneralSecurityException;
 import java.util.Arrays;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-public class SignatureTest extends BrambleTestCase {
+public abstract class SignatureTest extends BrambleTestCase {
 
-	private final CryptoComponent crypto;
+	protected final CryptoComponent crypto;
 
 	private final byte[] publicKey, privateKey;
 	private final String label = StringUtils.getRandomString(42);
 	private final byte[] inputBytes = TestUtils.getRandomBytes(123);
 
-	public SignatureTest() {
-		crypto = new CryptoComponentImpl(new TestSecureRandomProvider());
-		KeyPair k = crypto.generateSignatureKeyPair();
+	protected abstract KeyPair generateKeyPair();
+
+	protected abstract byte[] sign(String label, byte[] toSign,
+			byte[] privateKey) throws GeneralSecurityException;
+
+	protected abstract boolean verify(String label, byte[] signedData,
+			byte[] publicKey, byte[] signature) throws GeneralSecurityException;
+
+	SignatureTest() {
+		crypto = new CryptoComponentImpl(new TestSecureRandomProvider(), null);
+		KeyPair k = generateKeyPair();
 		publicKey = k.getPublic().getEncoded();
 		privateKey = k.getPrivate().getEncoded();
 	}
@@ -33,19 +42,19 @@ public class SignatureTest extends BrambleTestCase {
 	public void testIdenticalKeysAndInputsProduceIdenticalSignatures()
 			throws Exception {
 		// Calculate the Signature twice - the results should be identical
-		byte[] sig1 = crypto.sign(label, inputBytes, privateKey);
-		byte[] sig2 = crypto.sign(label, inputBytes, privateKey);
+		byte[] sig1 = sign(label, inputBytes, privateKey);
+		byte[] sig2 = sign(label, inputBytes, privateKey);
 		assertArrayEquals(sig1, sig2);
 	}
 
 	@Test
 	public void testDifferentKeysProduceDifferentSignatures() throws Exception {
 		// Generate second private key
-		KeyPair k2 = crypto.generateSignatureKeyPair();
+		KeyPair k2 = generateKeyPair();
 		byte[] privateKey2 = k2.getPrivate().getEncoded();
 		// Calculate the signature with each key
-		byte[] sig1 = crypto.sign(label, inputBytes, privateKey);
-		byte[] sig2 = crypto.sign(label, inputBytes, privateKey2);
+		byte[] sig1 = sign(label, inputBytes, privateKey);
+		byte[] sig2 = sign(label, inputBytes, privateKey2);
 		assertFalse(Arrays.equals(sig1, sig2));
 	}
 
@@ -56,8 +65,8 @@ public class SignatureTest extends BrambleTestCase {
 		byte[] inputBytes2 = TestUtils.getRandomBytes(123);
 		// Calculate the signature with different inputs
 		// the results should be different
-		byte[] sig1 = crypto.sign(label, inputBytes, privateKey);
-		byte[] sig2 = crypto.sign(label, inputBytes2, privateKey);
+		byte[] sig1 = sign(label, inputBytes, privateKey);
+		byte[] sig2 = sign(label, inputBytes2, privateKey);
 		assertFalse(Arrays.equals(sig1, sig2));
 	}
 
@@ -68,25 +77,25 @@ public class SignatureTest extends BrambleTestCase {
 		String label2 = StringUtils.getRandomString(42);
 		// Calculate the signature with different inputs
 		// the results should be different
-		byte[] sig1 = crypto.sign(label, inputBytes, privateKey);
-		byte[] sig2 = crypto.sign(label2, inputBytes, privateKey);
+		byte[] sig1 = sign(label, inputBytes, privateKey);
+		byte[] sig2 = sign(label2, inputBytes, privateKey);
 		assertFalse(Arrays.equals(sig1, sig2));
 	}
 
 	@Test
 	public void testSignatureVerification() throws Exception {
-		byte[] sig = crypto.sign(label, inputBytes, privateKey);
-		assertTrue(crypto.verify(label, inputBytes, publicKey, sig));
+		byte[] sig = sign(label, inputBytes, privateKey);
+		assertTrue(verify(label, inputBytes, publicKey, sig));
 	}
 
 	@Test
 	public void testDifferentKeyFailsVerification() throws Exception {
 		// Generate second private key
-		KeyPair k2 = crypto.generateSignatureKeyPair();
+		KeyPair k2 = generateKeyPair();
 		byte[] privateKey2 = k2.getPrivate().getEncoded();
 		// calculate the signature with different key, should fail to verify
-		byte[] sig = crypto.sign(label, inputBytes, privateKey2);
-		assertFalse(crypto.verify(label, inputBytes, publicKey, sig));
+		byte[] sig = sign(label, inputBytes, privateKey2);
+		assertFalse(verify(label, inputBytes, publicKey, sig));
 	}
 
 	@Test
@@ -94,8 +103,8 @@ public class SignatureTest extends BrambleTestCase {
 		// Generate a second input
 		byte[] inputBytes2 = TestUtils.getRandomBytes(123);
 		// calculate the signature with different input, should fail to verify
-		byte[] sig = crypto.sign(label, inputBytes, privateKey);
-		assertFalse(crypto.verify(label, inputBytes2, publicKey, sig));
+		byte[] sig = sign(label, inputBytes, privateKey);
+		assertFalse(verify(label, inputBytes2, publicKey, sig));
 	}
 
 	@Test
@@ -103,8 +112,8 @@ public class SignatureTest extends BrambleTestCase {
 		// Generate a second label
 		String label2 = StringUtils.getRandomString(42);
 		// calculate the signature with different label, should fail to verify
-		byte[] sig = crypto.sign(label, inputBytes, privateKey);
-		assertFalse(crypto.verify(label2, inputBytes, publicKey, sig));
+		byte[] sig = sign(label, inputBytes, privateKey);
+		assertFalse(verify(label2, inputBytes, publicKey, sig));
 	}
 
 }

bramble-core/src/test/java/org/briarproject/bramble/crypto/TagEncodingTest.java

@@ -3,9 +3,8 @@ package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.test.BrambleTestCase;
-import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
+import org.briarproject.bramble.api.crypto.TransportCrypto;
+import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.junit.Test;
 
 import java.util.HashSet;
@@ -14,25 +13,25 @@ import java.util.Set;
 import static junit.framework.TestCase.assertTrue;
 import static org.briarproject.bramble.api.transport.TransportConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENGTH;
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 
-public class TagEncodingTest extends BrambleTestCase {
+public class TagEncodingTest extends BrambleMockTestCase {
 
-	private final CryptoComponent crypto;
-	private final SecretKey tagKey;
+	private final CryptoComponent crypto = context.mock(CryptoComponent.class);
+
+	private final TransportCrypto transportCrypto =
+			new TransportCryptoImpl(crypto);
+	private final SecretKey tagKey = getSecretKey();
 	private final long streamNumber = 1234567890;
 
-	public TagEncodingTest() {
-		crypto = new CryptoComponentImpl(new TestSecureRandomProvider());
-		tagKey = TestUtils.getSecretKey();
-	}
-
 	@Test
 	public void testKeyAffectsTag() throws Exception {
 		Set<Bytes> set = new HashSet<>();
 		for (int i = 0; i < 100; i++) {
 			byte[] tag = new byte[TAG_LENGTH];
-			SecretKey tagKey = TestUtils.getSecretKey();
-			crypto.encodeTag(tag, tagKey, PROTOCOL_VERSION, streamNumber);
+			SecretKey tagKey = getSecretKey();
+			transportCrypto.encodeTag(tag, tagKey, PROTOCOL_VERSION,
+					streamNumber);
 			assertTrue(set.add(new Bytes(tag)));
 		}
 	}
@@ -42,7 +41,8 @@ public class TagEncodingTest extends BrambleTestCase {
 		Set<Bytes> set = new HashSet<>();
 		for (int i = 0; i < 100; i++) {
 			byte[] tag = new byte[TAG_LENGTH];
-			crypto.encodeTag(tag, tagKey, PROTOCOL_VERSION + i, streamNumber);
+			transportCrypto.encodeTag(tag, tagKey, PROTOCOL_VERSION + i,
+					streamNumber);
 			assertTrue(set.add(new Bytes(tag)));
 		}
 	}
@@ -52,7 +52,8 @@ public class TagEncodingTest extends BrambleTestCase {
 		Set<Bytes> set = new HashSet<>();
 		for (int i = 0; i < 100; i++) {
 			byte[] tag = new byte[TAG_LENGTH];
-			crypto.encodeTag(tag, tagKey, PROTOCOL_VERSION, streamNumber + i);
+			transportCrypto.encodeTag(tag, tagKey, PROTOCOL_VERSION,
+					streamNumber + i);
 			assertTrue(set.add(new Bytes(tag)));
 		}
 	}

bramble-core/src/test/java/org/briarproject/bramble/db/BasicDatabaseTest.java

@@ -0,0 +1,380 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.TestUtils;
+import org.briarproject.bramble.util.StringUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.sql.Types.BINARY;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public abstract class BasicDatabaseTest extends BrambleTestCase {
+
+	private static final int BATCH_SIZE = 100;
+
+	private final File testDir = TestUtils.getTestDirectory();
+	private final File db = new File(testDir, "db");
+
+	protected abstract String getBinaryType();
+
+	protected abstract String getDriverName();
+
+	protected abstract Connection openConnection(File db, boolean encrypt)
+			throws SQLException;
+
+	protected abstract void shutdownDatabase(File db, boolean encrypt)
+			throws SQLException;
+
+	@Before
+	public void setUp() throws Exception {
+		testDir.mkdirs();
+		Class.forName(getDriverName());
+	}
+
+	@Test
+	public void testInsertUpdateAndDelete() throws Exception {
+		Connection connection = openConnection(db, false);
+		try {
+			// Create the table
+			createTable(connection);
+			// Generate an ID and two names
+			byte[] id = TestUtils.getRandomId();
+			String oldName = StringUtils.getRandomString(50);
+			String newName = StringUtils.getRandomString(50);
+			// Insert the ID and old name into the table
+			insertRow(connection, id, oldName);
+			// Check that the old name can be retrieved using the ID
+			assertTrue(rowExists(connection, id));
+			assertEquals(oldName, getName(connection, id));
+			// Update the name
+			updateRow(connection, id, newName);
+			// Check that the new name can be retrieved using the ID
+			assertTrue(rowExists(connection, id));
+			assertEquals(newName, getName(connection, id));
+			// Delete the row from the table
+			assertTrue(deleteRow(connection, id));
+			// Check that the row no longer exists
+			assertFalse(rowExists(connection, id));
+			// Deleting the row again should have no effect
+			assertFalse(deleteRow(connection, id));
+		} finally {
+			connection.close();
+			shutdownDatabase(db, false);
+		}
+	}
+
+	@Test
+	public void testBatchInsertUpdateAndDelete() throws Exception {
+		Connection connection = openConnection(db, false);
+		try {
+			// Create the table
+			createTable(connection);
+			// Generate some IDs and two sets of names
+			byte[][] ids = new byte[BATCH_SIZE][];
+			String[] oldNames = new String[BATCH_SIZE];
+			String[] newNames = new String[BATCH_SIZE];
+			for (int i = 0; i < BATCH_SIZE; i++) {
+				ids[i] = TestUtils.getRandomId();
+				oldNames[i] = StringUtils.getRandomString(50);
+				newNames[i] = StringUtils.getRandomString(50);
+			}
+			// Insert the IDs and old names into the table as a batch
+			insertBatch(connection, ids, oldNames);
+			// Update the names as a batch
+			updateBatch(connection, ids, newNames);
+			// Check that the new names can be retrieved using the IDs
+			for (int i = 0; i < BATCH_SIZE; i++) {
+				assertTrue(rowExists(connection, ids[i]));
+				assertEquals(newNames[i], getName(connection, ids[i]));
+			}
+			// Delete the rows as a batch
+			boolean[] deleted = deleteBatch(connection, ids);
+			// Check that the rows no longer exist
+			for (int i = 0; i < BATCH_SIZE; i++) {
+				assertTrue(deleted[i]);
+				assertFalse(rowExists(connection, ids[i]));
+			}
+			// Deleting the rows again should have no effect
+			deleted = deleteBatch(connection, ids);
+			for (int i = 0; i < BATCH_SIZE; i++) assertFalse(deleted[i]);
+		} finally {
+			connection.close();
+			shutdownDatabase(db, false);
+		}
+	}
+
+	@Test
+	public void testSortOrder() throws Exception {
+		byte[] first = new byte[] {
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0
+		};
+		byte[] second = new byte[] {
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 127
+		};
+		byte[] third = new byte[] {
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, 0,
+				0, 0, 0, 0, 0, 0, 0, (byte) 255
+		};
+		Connection connection = openConnection(db, false);
+		try {
+			// Create the table
+			createTable(connection);
+			// Insert the rows
+			insertRow(connection, first, "first");
+			insertRow(connection, second, "second");
+			insertRow(connection, third, "third");
+			insertRow(connection, null, "null");
+			// Check the ordering of the < operator: null is not comparable
+			assertNull(getPredecessor(connection, first));
+			assertEquals("first", getPredecessor(connection, second));
+			assertEquals("second", getPredecessor(connection, third));
+			assertNull(getPredecessor(connection, null));
+			// Check the ordering of ORDER BY: nulls come first
+			List<String> names = getNames(connection);
+			assertEquals(4, names.size());
+			assertEquals("null", names.get(0));
+			assertEquals("first", names.get(1));
+			assertEquals("second", names.get(2));
+			assertEquals("third", names.get(3));
+		} finally {
+			connection.close();
+			shutdownDatabase(db, false);
+		}
+	}
+
+	@Test
+	public void testDataIsFoundWithoutEncryption() throws Exception {
+		testEncryption(false);
+	}
+
+	@Test
+	public void testDataIsNotFoundWithEncryption() throws Exception {
+		testEncryption(true);
+	}
+
+	private void testEncryption(boolean encrypt) throws Exception {
+		byte[] sequence = new byte[] {'a', 'b', 'c', 'd', 'e', 'f', 'g'};
+		Connection connection = openConnection(db, encrypt);
+		try {
+			createTable(connection);
+			insertRow(connection, sequence, "abcdefg");
+		} finally {
+			connection.close();
+			shutdownDatabase(db, encrypt);
+		}
+		try {
+			if (findSequence(testDir, sequence) == encrypt) fail();
+		} finally {
+			shutdownDatabase(db, encrypt);
+		}
+	}
+
+	private void createTable(Connection connection) throws SQLException {
+		Statement s = connection.createStatement();
+		String sql = "CREATE TABLE foo (uniqueId " + getBinaryType() + ","
+				+ " name VARCHAR(100) NOT NULL)";
+		s.executeUpdate(sql);
+		s.close();
+	}
+
+	private void insertRow(Connection connection, byte[] id, String name)
+			throws SQLException {
+		String sql = "INSERT INTO foo (uniqueId, name) VALUES (?, ?)";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		if (id == null) ps.setNull(1, BINARY);
+		else ps.setBytes(1, id);
+		ps.setString(2, name);
+		int affected = ps.executeUpdate();
+		assertEquals(1, affected);
+		ps.close();
+	}
+
+	private boolean rowExists(Connection connection, byte[] id)
+			throws SQLException {
+		assertNotNull(id);
+		String sql = "SELECT * FROM foo WHERE uniqueID = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		ps.setBytes(1, id);
+		ResultSet rs = ps.executeQuery();
+		boolean found = rs.next();
+		assertFalse(rs.next());
+		rs.close();
+		ps.close();
+		return found;
+	}
+
+	private String getName(Connection connection, byte[] id)
+			throws SQLException {
+		assertNotNull(id);
+		String sql = "SELECT name FROM foo WHERE uniqueID = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		ps.setBytes(1, id);
+		ResultSet rs = ps.executeQuery();
+		assertTrue(rs.next());
+		String name = rs.getString(1);
+		assertFalse(rs.next());
+		rs.close();
+		ps.close();
+		return name;
+	}
+
+	private void updateRow(Connection connection, byte[] id, String name)
+			throws SQLException {
+		String sql = "UPDATE foo SET name = ? WHERE uniqueId = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		if (id == null) ps.setNull(2, BINARY);
+		else ps.setBytes(2, id);
+		ps.setString(1, name);
+		assertEquals(1, ps.executeUpdate());
+		ps.close();
+	}
+
+	private boolean deleteRow(Connection connection, byte[] id)
+			throws SQLException {
+		String sql = "DELETE FROM foo WHERE uniqueId = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		if (id == null) ps.setNull(1, BINARY);
+		else ps.setBytes(1, id);
+		int affected = ps.executeUpdate();
+		ps.close();
+		return affected == 1;
+	}
+
+	private void insertBatch(Connection connection, byte[][] ids,
+			String[] names) throws SQLException {
+		assertEquals(ids.length, names.length);
+		String sql = "INSERT INTO foo (uniqueId, name) VALUES (?, ?)";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		for (int i = 0; i < ids.length; i++) {
+			if (ids[i] == null) ps.setNull(1, BINARY);
+			else ps.setBytes(1, ids[i]);
+			ps.setString(2, names[i]);
+			ps.addBatch();
+		}
+		int[] batchAffected = ps.executeBatch();
+		assertEquals(ids.length, batchAffected.length);
+		for (int affected : batchAffected) assertEquals(1, affected);
+		ps.close();
+	}
+
+	private void updateBatch(Connection connection, byte[][] ids,
+			String[] names) throws SQLException {
+		assertEquals(ids.length, names.length);
+		String sql = "UPDATE foo SET name = ? WHERE uniqueId = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		for (int i = 0; i < ids.length; i++) {
+			if (ids[i] == null) ps.setNull(2, BINARY);
+			else ps.setBytes(2, ids[i]);
+			ps.setString(1, names[i]);
+			ps.addBatch();
+		}
+		int[] batchAffected = ps.executeBatch();
+		assertEquals(ids.length, batchAffected.length);
+		for (int affected : batchAffected) assertEquals(1, affected);
+		ps.close();
+	}
+
+	private boolean[] deleteBatch(Connection connection, byte[][] ids)
+			throws SQLException {
+		String sql = "DELETE FROM foo WHERE uniqueId = ?";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		for (byte[] id : ids) {
+			if (id == null) ps.setNull(1, BINARY);
+			else ps.setBytes(1, id);
+			ps.addBatch();
+		}
+		int[] batchAffected = ps.executeBatch();
+		assertEquals(ids.length, batchAffected.length);
+		boolean[] ret = new boolean[ids.length];
+		for (int i = 0; i < batchAffected.length; i++)
+			ret[i] = batchAffected[i] == 1;
+		ps.close();
+		return ret;
+	}
+
+	private String getPredecessor(Connection connection, byte[] id)
+			throws SQLException {
+		String sql = "SELECT name FROM foo WHERE uniqueId < ?"
+				+ " ORDER BY uniqueId DESC";
+		PreparedStatement ps = connection.prepareStatement(sql);
+		ps.setBytes(1, id);
+		ps.setMaxRows(1);
+		ResultSet rs = ps.executeQuery();
+		String name = rs.next() ? rs.getString(1) : null;
+		assertFalse(rs.next());
+		rs.close();
+		ps.close();
+		return name;
+	}
+
+	private List<String> getNames(Connection connection) throws SQLException {
+		String sql = "SELECT name FROM foo ORDER BY uniqueId NULLS FIRST";
+		List<String> names = new ArrayList<>();
+		PreparedStatement ps = connection.prepareStatement(sql);
+		ResultSet rs = ps.executeQuery();
+		while (rs.next()) names.add(rs.getString(1));
+		rs.close();
+		ps.close();
+		return names;
+	}
+
+	private boolean findSequence(File f, byte[] sequence) throws IOException {
+		if (f.isDirectory()) {
+			File[] children = f.listFiles();
+			if (children != null)
+				for (File child : children)
+					if (findSequence(child, sequence)) return true;
+			return false;
+		} else if (f.isFile()) {
+			FileInputStream in = new FileInputStream(f);
+			try {
+				int offset = 0;
+				while (true) {
+					int read = in.read();
+					if (read == -1) return false;
+					if (((byte) read) == sequence[offset]) {
+						offset++;
+						if (offset == sequence.length) return true;
+					} else {
+						offset = 0;
+					}
+				}
+			} finally {
+				in.close();
+			}
+		} else {
+			return false;
+		}
+	}
+
+	@After
+	public void tearDown() throws Exception {
+		TestUtils.deleteTestDirectory(testDir);
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/db/BasicH2Test.java

@@ -1,345 +1,46 @@
 package org.briarproject.bramble.db;
 
-import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.test.TestUtils;
 import org.briarproject.bramble.util.StringUtils;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
 
 import java.io.File;
 import java.sql.Connection;
 import java.sql.DriverManager;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.ArrayList;
-import java.util.List;
+import java.util.Properties;
 
-import static java.sql.Types.BINARY;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
+public class BasicH2Test extends BasicDatabaseTest {
 
-public class BasicH2Test extends BrambleTestCase {
+	private final SecretKey key = TestUtils.getSecretKey();
 
-	private static final String CREATE_TABLE =
-			"CREATE TABLE foo (uniqueId BINARY(32), name VARCHAR NOT NULL)";
-	private static final int BATCH_SIZE = 100;
-
-	private final File testDir = TestUtils.getTestDirectory();
-	private final File db = new File(testDir, "db");
-	private final String url = "jdbc:h2:" + db.getAbsolutePath();
-
-	private Connection connection = null;
-
-	@Before
-	public void setUp() throws Exception {
-		testDir.mkdirs();
-		Class.forName("org.h2.Driver");
-		connection = DriverManager.getConnection(url);
+	@Override
+	protected String getBinaryType() {
+		return "BINARY(32)";
 	}
 
-	@Test
-	public void testInsertUpdateAndDelete() throws Exception {
-		// Create the table
-		createTable(connection);
-		// Generate an ID and two names
-		byte[] id = TestUtils.getRandomId();
-		String oldName = StringUtils.getRandomString(50);
-		String newName = StringUtils.getRandomString(50);
-		// Insert the ID and old name into the table
-		insertRow(id, oldName);
-		// Check that the old name can be retrieved using the ID
-		assertTrue(rowExists(id));
-		assertEquals(oldName, getName(id));
-		// Update the name
-		updateRow(id, newName);
-		// Check that the new name can be retrieved using the ID
-		assertTrue(rowExists(id));
-		assertEquals(newName, getName(id));
-		// Delete the row from the table
-		assertTrue(deleteRow(id));
-		// Check that the row no longer exists
-		assertFalse(rowExists(id));
-		// Deleting the row again should have no effect
-		assertFalse(deleteRow(id));
+	@Override
+	protected String getDriverName() {
+		return "org.h2.Driver";
 	}
 
-	@Test
-	public void testBatchInsertUpdateAndDelete() throws Exception {
-		// Create the table
-		createTable(connection);
-		// Generate some IDs and two sets of names
-		byte[][] ids = new byte[BATCH_SIZE][];
-		String[] oldNames = new String[BATCH_SIZE];
-		String[] newNames = new String[BATCH_SIZE];
-		for (int i = 0; i < BATCH_SIZE; i++) {
-			ids[i] = TestUtils.getRandomId();
-			oldNames[i] = StringUtils.getRandomString(50);
-			newNames[i] = StringUtils.getRandomString(50);
+	@Override
+	protected Connection openConnection(File db, boolean encrypt)
+			throws SQLException {
+		String url = "jdbc:h2:split:" + db.getAbsolutePath();
+		Properties props = new Properties();
+		props.setProperty("user", "user");
+		if (encrypt) {
+			url += ";CIPHER=AES";
+			String hex = StringUtils.toHexString(key.getBytes());
+			props.setProperty("password", hex + " password");
 		}
-		// Insert the IDs and old names into the table as a batch
-		insertBatch(ids, oldNames);
-		// Update the names as a batch
-		updateBatch(ids, newNames);
-		// Check that the new names can be retrieved using the IDs
-		for (int i = 0; i < BATCH_SIZE; i++) {
-			assertTrue(rowExists(ids[i]));
-			assertEquals(newNames[i], getName(ids[i]));
-		}
-		// Delete the rows as a batch
-		boolean[] deleted = deleteBatch(ids);
-		// Check that the rows no longer exist
-		for (int i = 0; i < BATCH_SIZE; i++) {
-			assertTrue(deleted[i]);
-			assertFalse(rowExists(ids[i]));
-		}
-		// Deleting the rows again should have no effect
-		deleted = deleteBatch(ids);
-		for (int i = 0; i < BATCH_SIZE; i++) assertFalse(deleted[i]);
+		return DriverManager.getConnection(url, props);
 	}
 
-	@Test
-	public void testSortOrder() throws Exception {
-		byte[] first = new byte[] {
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0
-		};
-		byte[] second = new byte[] {
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 127
-		};
-		byte[] third = new byte[] {
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, 0,
-				0, 0, 0, 0, 0, 0, 0, (byte) 255
-		};
-		// Create the table
-		createTable(connection);
-		// Insert the rows
-		insertRow(first, "first");
-		insertRow(second, "second");
-		insertRow(third, "third");
-		insertRow(null, "null");
-		// Check the ordering of the < operator: the null ID is not comparable
-		assertNull(getPredecessor(first));
-		assertEquals("first", getPredecessor(second));
-		assertEquals("second", getPredecessor(third));
-		assertNull(getPredecessor(null));
-		// Check the ordering of ORDER BY: nulls come first
-		List<String> names = getNames();
-		assertEquals(4, names.size());
-		assertEquals("null", names.get(0));
-		assertEquals("first", names.get(1));
-		assertEquals("second", names.get(2));
-		assertEquals("third", names.get(3));
-	}
-
-	private void createTable(Connection connection) throws SQLException {
-		try {
-			Statement s = connection.createStatement();
-			s.executeUpdate(CREATE_TABLE);
-			s.close();
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private void insertRow(byte[] id, String name) throws SQLException {
-		String sql = "INSERT INTO foo (uniqueId, name) VALUES (?, ?)";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			if (id == null) ps.setNull(1, BINARY);
-			else ps.setBytes(1, id);
-			ps.setString(2, name);
-			int affected = ps.executeUpdate();
-			assertEquals(1, affected);
-			ps.close();
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private boolean rowExists(byte[] id) throws SQLException {
-		assertNotNull(id);
-		String sql = "SELECT NULL FROM foo WHERE uniqueID = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			ps.setBytes(1, id);
-			ResultSet rs = ps.executeQuery();
-			boolean found = rs.next();
-			assertFalse(rs.next());
-			rs.close();
-			ps.close();
-			return found;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private String getName(byte[] id) throws SQLException {
-		assertNotNull(id);
-		String sql = "SELECT name FROM foo WHERE uniqueID = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			ps.setBytes(1, id);
-			ResultSet rs = ps.executeQuery();
-			assertTrue(rs.next());
-			String name = rs.getString(1);
-			assertFalse(rs.next());
-			rs.close();
-			ps.close();
-			return name;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private void updateRow(byte[] id, String name) throws SQLException {
-		String sql = "UPDATE foo SET name = ? WHERE uniqueId = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			if (id == null) ps.setNull(2, BINARY);
-			else ps.setBytes(2, id);
-			ps.setString(1, name);
-			assertEquals(1, ps.executeUpdate());
-			ps.close();
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private boolean deleteRow(byte[] id) throws SQLException {
-		String sql = "DELETE FROM foo WHERE uniqueId = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			if (id == null) ps.setNull(1, BINARY);
-			else ps.setBytes(1, id);
-			int affected = ps.executeUpdate();
-			ps.close();
-			return affected == 1;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private void insertBatch(byte[][] ids, String[] names) throws SQLException {
-		assertEquals(ids.length, names.length);
-		String sql = "INSERT INTO foo (uniqueId, name) VALUES (?, ?)";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			for (int i = 0; i < ids.length; i++) {
-				if (ids[i] == null) ps.setNull(1, BINARY);
-				else ps.setBytes(1, ids[i]);
-				ps.setString(2, names[i]);
-				ps.addBatch();
-			}
-			int[] batchAffected = ps.executeBatch();
-			assertEquals(ids.length, batchAffected.length);
-			for (int affected : batchAffected) assertEquals(1, affected);
-			ps.close();
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private void updateBatch(byte[][] ids, String[] names) throws SQLException {
-		assertEquals(ids.length, names.length);
-		String sql = "UPDATE foo SET name = ? WHERE uniqueId = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			for (int i = 0; i < ids.length; i++) {
-				if (ids[i] == null) ps.setNull(2, BINARY);
-				else ps.setBytes(2, ids[i]);
-				ps.setString(1, names[i]);
-				ps.addBatch();
-			}
-			int[] batchAffected = ps.executeBatch();
-			assertEquals(ids.length, batchAffected.length);
-			for (int affected : batchAffected) assertEquals(1, affected);
-			ps.close();
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private boolean[] deleteBatch(byte[][] ids) throws SQLException {
-		String sql = "DELETE FROM foo WHERE uniqueId = ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			for (byte[] id : ids) {
-				if (id == null) ps.setNull(1, BINARY);
-				else ps.setBytes(1, id);
-				ps.addBatch();
-			}
-			int[] batchAffected = ps.executeBatch();
-			assertEquals(ids.length, batchAffected.length);
-			boolean[] ret = new boolean[ids.length];
-			for (int i = 0; i < batchAffected.length; i++)
-				ret[i] = batchAffected[i] == 1;
-			ps.close();
-			return ret;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private String getPredecessor(byte[] id) throws SQLException {
-		String sql = "SELECT name FROM foo WHERE uniqueId < ?"
-				+ " ORDER BY uniqueId DESC LIMIT ?";
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			ps.setBytes(1, id);
-			ps.setInt(2, 1);
-			ResultSet rs = ps.executeQuery();
-			String name = rs.next() ? rs.getString(1) : null;
-			assertFalse(rs.next());
-			rs.close();
-			ps.close();
-			return name;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	private List<String> getNames() throws SQLException {
-		String sql = "SELECT name FROM foo ORDER BY uniqueId";
-		List<String> names = new ArrayList<>();
-		try {
-			PreparedStatement ps = connection.prepareStatement(sql);
-			ResultSet rs = ps.executeQuery();
-			while (rs.next()) names.add(rs.getString(1));
-			rs.close();
-			ps.close();
-			return names;
-		} catch (SQLException e) {
-			connection.close();
-			throw e;
-		}
-	}
-
-	@After
-	public void tearDown() throws Exception {
-		if (connection != null) connection.close();
-		TestUtils.deleteTestDirectory(testDir);
+	@Override
+	protected void shutdownDatabase(File db, boolean encrypt)
+			throws SQLException {
+		// The DB is closed automatically when the connection is closed
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/BasicHyperSqlTest.java

@@ -0,0 +1,48 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.test.TestUtils;
+import org.briarproject.bramble.util.StringUtils;
+
+import java.io.File;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class BasicHyperSqlTest extends BasicDatabaseTest {
+
+	private final SecretKey key = TestUtils.getSecretKey();
+
+	@Override
+	protected String getBinaryType() {
+		return "BINARY(32)";
+	}
+
+	@Override
+	protected String getDriverName() {
+		return "org.hsqldb.jdbc.JDBCDriver";
+	}
+
+	@Override
+	protected Connection openConnection(File db, boolean encrypt)
+			throws SQLException {
+		String url = "jdbc:hsqldb:file:" + db.getAbsolutePath() +
+				";sql.enforce_size=false;allow_empty_batch=true";
+		if (encrypt) {
+			String hex = StringUtils.toHexString(key.getBytes());
+			url += ";encrypt_lobs=true;crypt_type=AES;crypt_key=" + hex;
+		}
+		return DriverManager.getConnection(url);
+	}
+
+	@Override
+	protected void shutdownDatabase(File db, boolean encrypt)
+			throws SQLException {
+		Connection c = openConnection(db, encrypt);
+		Statement s = c.createStatement();
+		s.executeQuery("SHUTDOWN");
+		s.close();
+		c.close();
+	}
+}