Bump version numbers for 1.1.9 release.

Use trimmed length when deciding whether text is empty

Closes #1609

See merge request briar/briar!1153

.gitlab-ci.yml

@@ -1,6 +1,11 @@
 image: briar/ci-image-android:latest
 
+stages:
+- test
+- check_reproducibility
+
 test:
+  stage: test
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
@@ -21,6 +26,7 @@ test:
 
 
 test_reproducible:
+  stage: check_reproducibility
   script:
     - "curl -X POST -F token=${RELEASE_CHECK_TOKEN} -F ref=master -F variables[RELEASE_TAG]=${CI_COMMIT_REF_NAME} https://code.briarproject.org/api/v4/projects/61/trigger/pipeline"
   only:

.idea/codeStyles/Project.xml

@@ -39,31 +39,6 @@
     <JetCodeStyleSettings>
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
-    <Objective-C-extensions>
-      <file>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
-      </file>
-      <class>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
-      </class>
-      <extensions>
-        <pair source="cpp" header="h" fileNamingConvention="NONE" />
-        <pair source="c" header="h" fileNamingConvention="NONE" />
-      </extensions>
-    </Objective-C-extensions>
     <XML>
       <option name="XML_LEGACY_SETTINGS_IMPORTED" value="true" />
     </XML>

.idea/runConfigurations/All_in_briar_headless.xml

@@ -1,20 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="All in briar-headless" type="AndroidJUnit" factoryName="Android JUnit" nameIsGenerated="true">
-    <module name="briar-headless" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
-    <option name="PACKAGE_NAME" value="org.briarproject.briar.headless" />
-    <option name="MAIN_CLASS_NAME" value="" />
-    <option name="METHOD_NAME" value="" />
-    <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="" />
-    <option name="PARAMETERS" value="" />
-    <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-headless" />
-    <option name="PASS_PARENT_ENVS" value="true" />
-    <option name="TEST_SEARCH_SCOPE">
-      <value defaultName="singleModule" />
-    </option>
-    <patterns />
-    <method />
-  </configuration>
-</component>

.idea/runConfigurations/All_tests.xml

@@ -1,30 +1,20 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests" type="AndroidJUnit" factoryName="Android JUnit">
-    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
     <module name="briar-android" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
-    <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-android" />
-    <option name="ENV_VARIABLES" />
-    <option name="PASS_PARENT_ENVS" value="true" />
-    <option name="TEST_SEARCH_SCOPE">
-      <value defaultName="singleModule" />
-    </option>
-    <envs />
-    <patterns />
-    <method>
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/briar-android" />
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-api" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-core" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-android" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-java" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in briar-core" run_configuration_type="AndroidJUnit" />
-      <option name="RunConfigurationTask" enabled="true" run_configuration_name="All in briar-headless" run_configuration_type="AndroidJUnit" />
+      <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in briar-headless" run_configuration_type="AndroidJUnit" />
     </method>
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_headless.xml

@@ -0,0 +1,15 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="All tests in briar-headless" type="AndroidJUnit" factoryName="Android JUnit">
+    <module name="briar-headless" />
+    <option name="PACKAGE_NAME" value="org.briarproject.briar.headless" />
+    <option name="MAIN_CLASS_NAME" value="" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="package" />
+    <option name="VM_PARAMETERS" />
+    <option name="PARAMETERS" value="" />
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/briar-headless" />
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

bramble-android/build.gradle

@@ -11,8 +11,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 10105
-		versionName "1.1.5"
+		versionCode 10109
+		versionName "1.1.9"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -30,10 +30,10 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.4.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.7@zip'
+	tor 'org.briarproject:tor-android:0.3.5.8@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.9@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidEagerSingletons.java

@@ -2,10 +2,13 @@ package org.briarproject.bramble;
 
 import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
+import org.briarproject.bramble.reporting.ReportingModule;
 
 public interface BrambleAndroidEagerSingletons {
 
 	void inject(AndroidBatteryModule.EagerSingletons init);
 
 	void inject(AndroidNetworkModule.EagerSingletons init);
+
+	void inject(ReportingModule.EagerSingletons init);
 }

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidModule.java

@@ -3,6 +3,8 @@ package org.briarproject.bramble;
 import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
 import org.briarproject.bramble.plugin.tor.CircumventionModule;
+import org.briarproject.bramble.reporting.ReportingModule;
+import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.system.AndroidSystemModule;
 
 import dagger.Module;
@@ -11,12 +13,15 @@ import dagger.Module;
 		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
-		CircumventionModule.class
+		CircumventionModule.class,
+		ReportingModule.class,
+		SocksModule.class
 })
 public class BrambleAndroidModule {
 
 	public static void initEagerSingletons(BrambleAndroidEagerSingletons c) {
 		c.inject(new AndroidBatteryModule.EagerSingletons());
 		c.inject(new AndroidNetworkModule.EagerSingletons());
+		c.inject(new ReportingModule.EagerSingletons());
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/account/AndroidAccountManager.java

@@ -9,14 +9,20 @@ import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
+import java.util.HashSet;
+import java.util.Set;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static android.os.Build.VERSION.SDK_INT;
+import static java.util.logging.Level.INFO;
+import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
+import static org.briarproject.bramble.util.LogUtils.logFileOrDir;
+
 class AndroidAccountManager extends AccountManagerImpl
 		implements AccountManager {
 
@@ -37,6 +43,16 @@ class AndroidAccountManager extends AccountManagerImpl
 		appContext = app.getApplicationContext();
 	}
 
+	@Override
+	public boolean accountExists() {
+		boolean exists = super.accountExists();
+		if (!exists && LOG.isLoggable(INFO)) {
+			LOG.info("Account does not exist. Contents of account directory:");
+			logFileOrDir(LOG, INFO, getDataDir());
+		}
+		return exists;
+	}
+
 	// Locking: stateChangeLock
 	@Override
 	@Nullable
@@ -70,9 +86,17 @@ class AndroidAccountManager extends AccountManagerImpl
 	@Override
 	public void deleteAccount() {
 		synchronized (stateChangeLock) {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Contents of account directory before deleting:");
+				logFileOrDir(LOG, INFO, getDataDir());
+			}
 			super.deleteAccount();
 			SharedPreferences defaultPrefs = getDefaultSharedPreferences();
 			deleteAppData(prefs, defaultPrefs);
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Contents of account directory after deleting:");
+				logFileOrDir(LOG, INFO, getDataDir());
+			}
 		}
 	}
 
@@ -89,20 +113,46 @@ class AndroidAccountManager extends AccountManagerImpl
 				LOG.warning("Could not clear shared preferences");
 		}
 		// Delete files, except lib and shared_prefs directories
-		File dataDir = new File(appContext.getApplicationInfo().dataDir);
-		File[] children = dataDir.listFiles();
-		if (children == null) {
+		Set<File> files = new HashSet<>();
+		File dataDir = getDataDir();
+		@Nullable
+		File[] fileArray = dataDir.listFiles();
+		if (fileArray == null) {
 			LOG.warning("Could not list files in app data dir");
 		} else {
-			for (File child : children) {
-				String name = child.getName();
+			for (File file : fileArray) {
+				String name = file.getName();
 				if (!name.equals("lib") && !name.equals("shared_prefs")) {
-					IoUtils.deleteFileOrDir(child);
+					files.add(file);
 				}
 			}
 		}
+		files.add(appContext.getFilesDir());
+		files.add(appContext.getCacheDir());
+		addIfNotNull(files, appContext.getExternalCacheDir());
+		if (SDK_INT >= 19) {
+			for (File file : appContext.getExternalCacheDirs()) {
+				addIfNotNull(files, file);
+			}
+		}
+		if (SDK_INT >= 21) {
+			for (File file : appContext.getExternalMediaDirs()) {
+				addIfNotNull(files, file);
+			}
+		}
+		for (File file : files) {
+			deleteFileOrDir(file);
+		}
 		// Recreate the cache dir as some OpenGL drivers expect it to exist
-		if (!new File(dataDir, "cache").mkdir())
+		if (!new File(dataDir, "cache").mkdirs())
 			LOG.warning("Could not recreate cache dir");
 	}
+
+	private File getDataDir() {
+		return new File(appContext.getApplicationInfo().dataDir);
+	}
+
+	private void addIfNotNull(Set<File> files, @Nullable File file) {
+		if (file != null) files.add(file);
+	}
 }

bramble-android/src/main/java/org/briarproject/bramble/battery/AndroidBatteryManager.java

@@ -19,9 +19,7 @@ import javax.inject.Inject;
 import static android.content.Intent.ACTION_BATTERY_CHANGED;
 import static android.content.Intent.ACTION_POWER_CONNECTED;
 import static android.content.Intent.ACTION_POWER_DISCONNECTED;
-import static android.os.BatteryManager.BATTERY_STATUS_CHARGING;
-import static android.os.BatteryManager.BATTERY_STATUS_FULL;
-import static android.os.BatteryManager.EXTRA_STATUS;
+import static android.os.BatteryManager.EXTRA_PLUGGED;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 
@@ -48,9 +46,8 @@ class AndroidBatteryManager implements BatteryManager, Service {
 		IntentFilter filter = new IntentFilter(ACTION_BATTERY_CHANGED);
 		Intent i = appContext.registerReceiver(null, filter);
 		if (i == null) return false;
-		int status = i.getIntExtra(EXTRA_STATUS, -1);
-		return status == BATTERY_STATUS_CHARGING ||
-				status == BATTERY_STATUS_FULL;
+		int status = i.getIntExtra(EXTRA_PLUGGED, 0);
+		return status != 0;
 	}
 
 	@Override

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -12,8 +12,8 @@ import android.content.IntentFilter;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
@@ -51,6 +51,7 @@ import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
@@ -58,7 +59,7 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	private static final Logger LOG =
-			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
+			getLogger(AndroidBluetoothPlugin.class.getName());
 
 	private static final int MAX_DISCOVERY_MS = 10_000;
 
@@ -75,7 +76,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
 			Executor ioExecutor, AndroidExecutor androidExecutor,
 			Context appContext, SecureRandom secureRandom, Clock clock,
-			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
+			Backoff backoff, PluginCallback callback, int maxLatency) {
 		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
 				maxLatency);
 		this.androidExecutor = androidExecutor;

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPluginFactory.java

@@ -6,9 +6,9 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
@@ -61,7 +61,7 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
 				new BluetoothConnectionLimiterImpl();
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,

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

@@ -13,7 +13,7 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -32,17 +32,18 @@ import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
+import static java.util.logging.Logger.getLogger;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
+	private static final Logger LOG =
+			getLogger(AndroidLanTcpPlugin.class.getName());
+
 	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);
@@ -60,7 +61,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	private volatile SocketFactory socketFactory;
 
 	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
-			Backoff backoff, DuplexPluginCallback callback, int maxLatency,
+			Backoff backoff, PluginCallback callback, int maxLatency,
 			int maxIdleTime) {
 		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
 		// Don't execute more than one connection status check at a time

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

@@ -6,9 +6,9 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
@@ -51,7 +51,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidLanTcpPlugin plugin = new AndroidLanTcpPlugin(ioExecutor,

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

@@ -11,7 +11,7 @@ import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
@@ -32,9 +32,6 @@ import static java.util.concurrent.TimeUnit.MINUTES;
 @ParametersNotNullByDefault
 class AndroidTorPlugin extends TorPlugin {
 
-	// This tag may prevent Huawei's power manager from killing us
-	private static final String WAKE_LOCK_TAG = "LocationManagerService";
-
 	private final Context appContext;
 	private final RenewableWakeLock wakeLock;
 
@@ -44,18 +41,19 @@ class AndroidTorPlugin extends TorPlugin {
 			Clock clock, ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager, Backoff backoff,
-			DuplexPluginCallback callback, String architecture, int maxLatency,
+			TorRendezvousCrypto torRendezvousCrypto,
+			PluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
 				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, callback, architecture, maxLatency, maxIdleTime,
+				backoff, torRendezvousCrypto, callback, architecture, maxLatency, maxIdleTime,
 				appContext.getDir("tor", MODE_PRIVATE));
 		this.appContext = appContext;
 		PowerManager pm = (PowerManager)
 				appContext.getSystemService(POWER_SERVICE);
 		if (pm == null) throw new AssertionError();
 		wakeLock = new RenewableWakeLock(pm, scheduler, PARTIAL_WAKE_LOCK,
-				WAKE_LOCK_TAG, 1, MINUTES);
+				getWakeLockTag(), 1, MINUTES);
 	}
 
 	@Override
@@ -87,4 +85,17 @@ class AndroidTorPlugin extends TorPlugin {
 		super.stop();
 		wakeLock.release();
 	}
+
+	private String getWakeLockTag() {
+		PackageManager pm = appContext.getPackageManager();
+		for (PackageInfo info : pm.getInstalledPackages(0)) {
+			String name = info.packageName.toLowerCase();
+			if (name.startsWith("com.huawei.powergenie")) {
+				return "LocationManagerService";
+			} else if (name.startsWith("com.evenwell.powermonitor")) {
+				return "AudioIn";
+			}
+		}
+		return getClass().getSimpleName();
+	}
 }

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

@@ -9,10 +9,10 @@ import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
@@ -84,7 +84,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 
 		// Check that we have a Tor binary for this architecture
 		String architecture = null;
@@ -106,10 +106,12 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
 		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor, scheduler,
 				appContext, networkManager, locationUtils, torSocketFactory,
 				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
+				backoff, torRendezvousCrypto, callback, architecture,
+				MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSystemModule.java

@@ -1,10 +1,13 @@
 package org.briarproject.bramble.system;
 
+import org.briarproject.bramble.api.event.EventExecutor;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
 
+import java.util.concurrent.Executor;
+
 import javax.inject.Singleton;
 
 import dagger.Module;
@@ -32,6 +35,13 @@ public class AndroidSystemModule {
 		return androidExecutor;
 	}
 
+	@Provides
+	@Singleton
+	@EventExecutor
+	Executor provideEventExecutor(AndroidExecutor androidExecutor) {
+		return androidExecutor::runOnUiThread;
+	}
+
 	@Provides
 	@Singleton
 	ResourceProvider provideResourceProvider(AndroidResourceProvider provider) {

bramble-android/src/test/java/org/briarproject/bramble/account/AndroidAccountManagerTest.java

@@ -112,6 +112,8 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		// Other directories should be deleted
 		File potatoDir = new File(testDir, ".potato");
 		File potatoFile = new File(potatoDir, "file");
+		File filesDir = new File(testDir, "filesDir");
+		File externalCacheDir = new File(testDir, "externalCacheDir");
 
 		context.checking(new Expectations() {{
 			oneOf(prefs).edit();
@@ -126,8 +128,14 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 			will(returnValue(editor));
 			oneOf(editor).commit();
 			will(returnValue(true));
-			oneOf(app).getApplicationInfo();
+			allowing(app).getApplicationInfo();
 			will(returnValue(applicationInfo));
+			oneOf(app).getFilesDir();
+			will(returnValue(filesDir));
+			oneOf(app).getCacheDir();
+			will(returnValue(cacheDir));
+			oneOf(app).getExternalCacheDir();
+			will(returnValue(externalCacheDir));
 		}});
 
 		assertTrue(dbDir.mkdirs());
@@ -140,6 +148,8 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		assertTrue(cacheFile.createNewFile());
 		assertTrue(potatoDir.mkdirs());
 		assertTrue(potatoFile.createNewFile());
+		assertTrue(filesDir.mkdirs());
+		assertTrue(externalCacheDir.mkdirs());
 
 		accountManager.deleteAccount();
 
@@ -153,6 +163,8 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		assertFalse(cacheFile.exists());
 		assertFalse(potatoDir.exists());
 		assertFalse(potatoFile.exists());
+		assertFalse(filesDir.exists());
+		assertFalse(externalCacheDir.exists());
 	}
 
 	@After

bramble-android/witness.gradle

@@ -1,47 +1,45 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:26.2.1:protos-26.2.1.jar:2f371f5b1f551e85ab08be4d6a2873471b3d44afd1ebf6aa3298f3b796bf691f',
-        'com.android.tools.analytics-library:shared:26.2.1:shared-26.2.1.jar:4c1e4e705fa4d45f23aaea230557f6508155012d9c296337787c1d7b26a97f5a',
-        'com.android.tools.analytics-library:tracker:26.2.1:tracker-26.2.1.jar:4a624ecc976539f755ddb0bb8dfc2dd3d08326cfec59a098dbd70f701ca7fb75',
-        'com.android.tools.build:aapt2:3.2.1-4818971:aapt2-3.2.1-4818971-linux.jar:f431b6f96c91a2c155144b091a9c97d9805c589fe8efc9c930b6cd346cb60a1e',
-        'com.android.tools.build:apksig:3.2.1:apksig-3.2.1.jar:2b46f2feffea66037aab29e4261b2433c190194a6ef97b958511eb157f2ccba5',
-        'com.android.tools.build:apkzlib:3.2.1:apkzlib-3.2.1.jar:c39ad0313905932431fe81c8899c2cf39a4d92ad6c4edcaa4b25432f461452aa',
-        'com.android.tools.build:builder-model:3.2.1:builder-model-3.2.1.jar:a9f68e6abcec122f9cb5ad352d3f05a3eb03acbcdca95e4d25c16310c2c965ff',
-        'com.android.tools.build:builder-test-api:3.2.1:builder-test-api-3.2.1.jar:533ac6c2b5884bb54967a33791f2628dfdfac7981af39417a333b43d4379b6be',
-        'com.android.tools.build:builder:3.2.1:builder-3.2.1.jar:aedcbfd115dbe91d09b4113e66ef50589b558d0aa3b2f133b1d867c9b87fae83',
-        'com.android.tools.build:gradle-api:3.2.1:gradle-api-3.2.1.jar:57cf0ac5ac1dca8afdb3f62b94265e776e7dcfa641cc3844fb53a05193de208d',
-        'com.android.tools.build:manifest-merger:26.2.1:manifest-merger-26.2.1.jar:8830573263361035d38cfdcb51e2db94029c93865b21334f5fbf8a27984281a6',
-        'com.android.tools.ddms:ddmlib:26.2.1:ddmlib-26.2.1.jar:a4bf0a29a19980bf27269465cc782064656750b77c26728f82f9e148b705218b',
-        'com.android.tools.external.com-intellij:intellij-core:26.2.1:intellij-core-26.2.1.jar:4925ad1892c2687cb1a63427d440ef519c8c59215fefe0dc5d541d5d411fcafe',
-        'com.android.tools.external.com-intellij:kotlin-compiler:26.2.1:kotlin-compiler-26.2.1.jar:daa064fd708f340ee25fb9823c4c74104ac77f1370b76d907eb9ae6daec0a2ae',
-        'com.android.tools.external.org-jetbrains:uast:26.2.1:uast-26.2.1.jar:f10f7258d2ab9189562cc0f9ad838c0378fdba439229173390a99de02ebac75b',
-        'com.android.tools.layoutlib:layoutlib-api:26.2.1:layoutlib-api-26.2.1.jar:ddbf4fca123733fa011595b1cc1f4ac2937ed327b60990711fafc33c775c2ade',
-        'com.android.tools.lint:lint-api:26.2.1:lint-api-26.2.1.jar:3b57e739de567b98bc9ab56c2c0ee66fc026b4adf5843e8f9804ca0666a6f66e',
-        'com.android.tools.lint:lint-checks:26.2.1:lint-checks-26.2.1.jar:c86f4cc9aaee722ee4ad70062f7b5af91e9b041914af27adc09f545ab0fb3bc6',
-        'com.android.tools.lint:lint-gradle-api:26.2.1:lint-gradle-api-26.2.1.jar:2283e7af32e301565f2a797e531f0fc8c648077d457afb3ffdddbee638976c2f',
-        'com.android.tools.lint:lint-gradle:26.2.1:lint-gradle-26.2.1.jar:8fd90b2f3ec788cbb9801c07ab3e1ea2255aa31a6093157d7ea0ff13d0315ecb',
-        'com.android.tools.lint:lint-kotlin:26.2.1:lint-kotlin-26.2.1.jar:7a6a5d2b18f69cf1b900d857c2632b4c683713c533295933b8b759f8cab4a877',
-        'com.android.tools.lint:lint:26.2.1:lint-26.2.1.jar:7848b82ae988b90dee259ae7c7e86e05cbf52db6cd21c8bbd38ce7df08f3f8c5',
-        'com.android.tools:annotations:26.2.1:annotations-26.2.1.jar:7391c6a1e080174b96e64ceb078dadd31ce4d8a2d2fee0ec65be202126f90f24',
-        'com.android.tools:common:26.2.1:common-26.2.1.jar:a50aab2d6411ff68f4004a87c7e93d87d8e980a0ec3b352246549897ea2d78e5',
-        'com.android.tools:dvlib:26.2.1:dvlib-26.2.1.jar:72a83bf2839b1df9b1fbf67ba45d1bfb9f966cd774da4320c762b2be8f1688aa',
-        'com.android.tools:repository:26.2.1:repository-26.2.1.jar:fa74dae09103faef703df38550ad8fa244c5b6d1bf90d6198be932292b3d9cc1',
-        'com.android.tools:sdk-common:26.2.1:sdk-common-26.2.1.jar:759d4b292ca69a35cf961fca377b54158fc6c88108978006999442e80a011cf4',
-        'com.android.tools:sdklib:26.2.1:sdklib-26.2.1.jar:248df7ad5eac4aeb6f96c394c76760de4b7b89ac056e54d0c21a739368b91b45',
+        'com.android.tools.analytics-library:protos:26.4.0:protos-26.4.0.jar:ad760915586797d39319f402837b378bff3bb4ed583e3e0c48c965631fb2135f',
+        'com.android.tools.analytics-library:shared:26.4.0:shared-26.4.0.jar:1332106a905d48909c81268c9e414946de3e83487db394c6073b0a9b5c3d0ed2',
+        'com.android.tools.analytics-library:tracker:26.4.0:tracker-26.4.0.jar:d0020cfbfd4cd75935f2972d6a24089840d4a10df6f3ef2a796093217dd37796',
+        'com.android.tools.build:apksig:3.4.0:apksig-3.4.0.jar:91d5a1866139c69756280355a6f61b4d619d0516841580114f45a10f2177327e',
+        'com.android.tools.build:apkzlib:3.4.0:apkzlib-3.4.0.jar:8653c85f5fdf1dde840e8b8af7396aeb79c34b66e541b5860059616006535592',
+        'com.android.tools.build:builder-model:3.4.0:builder-model-3.4.0.jar:a88f138124a9f016a70bcb4760359a502f65c7deed56507ee4014f4dd9ea853b',
+        'com.android.tools.build:builder-test-api:3.4.0:builder-test-api-3.4.0.jar:31089ab1ec19ca7687a010867d2f3807513c805b8226979706f4247b5d4df26f',
+        'com.android.tools.build:builder:3.4.0:builder-3.4.0.jar:476221b5203a7f50089bf185ed95000a34b6f5020ef0a17815afd58606922679',
+        'com.android.tools.build:gradle-api:3.4.0:gradle-api-3.4.0.jar:215eca38f6719213c2f492b4d622cdd11676c66c9871f8a2aed0c66d00175628',
+        'com.android.tools.build:manifest-merger:26.4.0:manifest-merger-26.4.0.jar:29e45e690dedd165035e97c21c2ca94d0bd4ec16b6b210daa26669a582b6f220',
+        'com.android.tools.ddms:ddmlib:26.4.0:ddmlib-26.4.0.jar:93f56fe4630c3166adbd6c51d7bb602d96abb91b07ba5b1165fdcd071e88c940',
+        'com.android.tools.external.com-intellij:intellij-core:26.4.0:intellij-core-26.4.0.jar:30cb0e879d4424de9677a50b537fb628636b4a50f5470af5e52437980c41421f',
+        'com.android.tools.external.com-intellij:kotlin-compiler:26.4.0:kotlin-compiler-26.4.0.jar:dd1fe225c31a0e012dc025336363a5b783e2c5c20ffb69e77f8f57e89420d998',
+        'com.android.tools.external.org-jetbrains:uast:26.4.0:uast-26.4.0.jar:f25f3285b775a983327583ff6584dea54e447813ef69e0ce08b05a45b5f4aab0',
+        'com.android.tools.layoutlib:layoutlib-api:26.4.0:layoutlib-api-26.4.0.jar:52128f5cf293b224072be361919bfd416e59480ab7264ddcdbbf046b0d7a12e3',
+        'com.android.tools.lint:lint-api:26.4.0:lint-api-26.4.0.jar:fdb8fca8ae4c254f438338d03d72605e00ed106f2d5550405af41ca1c8509401',
+        'com.android.tools.lint:lint-checks:26.4.0:lint-checks-26.4.0.jar:4ff52d40488cd3e22b9c6b2eb67784e0c3269d0b42ef9d17689cd75a7b2bceb4',
+        'com.android.tools.lint:lint-gradle-api:26.4.0:lint-gradle-api-26.4.0.jar:714b7a85c7d2aa10daeab16e969fe7530c659d0728a7f24021da456870418d0f',
+        'com.android.tools.lint:lint-gradle:26.4.0:lint-gradle-26.4.0.jar:b8c130d273f522388734457e1b96790f41528fcec6fda9e8eaa4e4d95a07cfbb',
+        'com.android.tools.lint:lint:26.4.0:lint-26.4.0.jar:83aa062fb0405b60ed358d858c8c2955e1bae44a455b498068c6a60988755f00',
+        'com.android.tools:annotations:26.4.0:annotations-26.4.0.jar:a7955b8e19c3a2a861d6faa43a58b7c0d46ea9112188ee3e235c6f9f439ecc1a',
+        'com.android.tools:common:26.4.0:common-26.4.0.jar:ea40b94b3c1284ea7700f011388e2906a8363a66abd902891722b3c557984852',
+        'com.android.tools:dvlib:26.4.0:dvlib-26.4.0.jar:23af89c535b01ba36ceed1b6b309b672814eba624e643cd7dedf0519edad50cc',
+        'com.android.tools:repository:26.4.0:repository-26.4.0.jar:3d1763ab46199374dc6d94129bba11c70f1d5857e2c81a3ac4898abca40b176b',
+        'com.android.tools:sdk-common:26.4.0:sdk-common-26.4.0.jar:78a522525b30ffc6b7bf1299c831d24ce385f68a9f4878f8f752e9baefa31b0f',
+        'com.android.tools:sdklib:26.4.0:sdklib-26.4.0.jar:b854c23892013a326d761cf071c72cf3e038ed0469d10f4a356829fa56e4c132',
         'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
+        'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
         'com.google.code.gson:gson:2.8.0:gson-2.8.0.jar:c6221763bd79c4f1c3dc7f750b5f29a0bb38b367b81314c4f71896e340c40825',
-        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
-        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
-        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
-        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
-        'com.google.errorprone:error_prone_annotations:2.0.18:error_prone_annotations-2.0.18.jar:cb4cfad870bf563a07199f3ebea5763f0dec440fcda0b318640b1feaa788656b',
+        'com.google.dagger:dagger-compiler:2.22.1:dagger-compiler-2.22.1.jar:e5f28302cbe70a79d3620cddebfb8ec0736814f3980ffe1e673bfe3342f507d3',
+        'com.google.dagger:dagger-producers:2.22.1:dagger-producers-2.22.1.jar:f834a0082014213a68ff06a0f048d750178d02196c58b0b15beb367d32b97e35',
+        'com.google.dagger:dagger-spi:2.22.1:dagger-spi-2.22.1.jar:4b0b922793b3bcb91b99fabb75dba77c68afd7ae4c5f0c4fd6ba681f0a291c7d',
+        'com.google.dagger:dagger:2.22.1:dagger-2.22.1.jar:329d4340f24c4f5717af016c097e90668bfea2a5376e6aa9964b01cef3fd241a',
         'com.google.errorprone:error_prone_annotations:2.1.3:error_prone_annotations-2.1.3.jar:03d0329547c13da9e17c634d1049ea2ead093925e290567e1a364fd6b1fc7ff8',
         'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
         'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
-        'com.google.guava:guava:23.0:guava-23.0.jar:7baa80df284117e5b945b19b98d367a85ea7b7801bd358ff657946c3bd1b6596',
         'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
-        'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
+        'com.google.guava:guava:26.0-jre:guava-26.0-jre.jar:a0e9cabad665bc20bcd2b01f108e5fc03f756e13aea80abaadb9f407033bea2c',
+        'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
         'com.google.protobuf:protobuf-java:3.4.0:protobuf-java-3.4.0.jar:dce7e66b32456a1b1198da0caff3a8acb71548658391e798c79369241e6490a4',
         'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
@@ -50,7 +48,7 @@ dependencyVerification {
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
         'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
         'com.sun.xml.fastinfoset:FastInfoset:1.2.13:FastInfoset-1.2.13.jar:27a77db909f3c2833c0b1a37c55af1db06045118ad2eed96ce567b6632bce038',
-        'commons-codec:commons-codec:1.9:commons-codec-1.9.jar:ad19d2601c3abf0b946b5c3a4113e226a8c1e3305e395b90013b78dd94a723ce',
+        'commons-codec:commons-codec:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
         'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
         'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
         'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
@@ -62,27 +60,28 @@ dependencyVerification {
         '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.apache.commons:commons-compress:1.12:commons-compress-1.12.jar:2c1542faf343185b7cab9c3d55c8ae5471d6d095d3887a4adefdbdf2984dc0b6',
-        'org.apache.httpcomponents:httpclient:4.5.2:httpclient-4.5.2.jar:0dffc621400d6c632f55787d996b8aeca36b30746a716e079a985f24d8074057',
-        'org.apache.httpcomponents:httpcore:4.4.5:httpcore-4.4.5.jar:64d5453874cab7e40a7065cb01a9a9ca1053845a9786b478878b679e0580cec3',
-        'org.apache.httpcomponents:httpmime:4.5.2:httpmime-4.5.2.jar:231a3f7e4962053db2be8461d5422e68fc458a3a7dd7d8ada803a348e21f8f07',
+        'org.apache.httpcomponents:httpclient:4.5.6:httpclient-4.5.6.jar:c03f813195e7a80e3608d0ddd8da80b21696a4c92a6a2298865bf149071551c7',
+        'org.apache.httpcomponents:httpcore:4.4.10:httpcore-4.4.10.jar:78ba1096561957db1b55200a159b648876430342d15d461277e62360da19f6fd',
+        'org.apache.httpcomponents:httpmime:4.5.6:httpmime-4.5.6.jar:0b2b1102c18d3c7e05a77214b9b7501a6f6056174ae5604e0e256776eda7553e',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.7:obfs4proxy-android-0.0.7.zip:abdfb5d889d848de9bf214f9276abbf454808a505b870819eccc9a9e985bf617',
-        'org.briarproject:tor-android:0.3.4.8:tor-android-0.3.4.8.zip:989a0352d9d8d8172cd6c2137654e165e5d2beb10ed1211bab3814e224ad1926',
+        'org.briarproject:obfs4proxy-android:0.0.9:obfs4proxy-android-0.0.9.zip:9b7e9181535ea8d8bbe8ae6338e08cf4c5fc1e357a779393e0ce49586d459ae0',
+        'org.briarproject:tor-android:0.3.5.8:tor-android-0.3.5.8.zip:42a13a6f185be1a62f42e3f30ce66a3c099ac5ec890a65e7593111b65b44a54a',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
-        'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
+        'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
+        'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
         'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
         'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
         'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
         '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.jetbrains.kotlin:kotlin-reflect:1.2.0:kotlin-reflect-1.2.0.jar:4f48a872bad6e4d9c053f4ad610d11e4012ad7e58dc19a03dd5eb811f36069dd',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.2.71:kotlin-stdlib-common-1.2.71.jar:63999687ff2fce8a592dd180ffbbf8f1d21c26b4044c55cdc74ff3cf3b3cf328',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.2.71:kotlin-stdlib-jdk7-1.2.71.jar:b136bd61b240e07d4d92ce00d3bd1dbf584400a7bf5f220c2f3cd22446858082',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.2.71:kotlin-stdlib-jdk8-1.2.71.jar:ac3c8abf47790b64b4f7e2509a53f0c145e061ac1612a597520535d199946ea9',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.2.71:kotlin-stdlib-1.2.71.jar:4c895c270b87f5fec2a2796e1d89c15407ee821de961527c28588bb46afbc68b',
+        'org.jetbrains.kotlin:kotlin-reflect:1.3.21:kotlin-reflect-1.3.21.jar:a3065c822633191e0a3e3ee12a29bec234fc4b2864a6bb87ef48cce3e9e0c26a',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.21:kotlin-stdlib-common-1.3.21.jar:cea61f7b611895e64f58569a9757fc0ab0d582f107211e1930e0ce2a0add52a7',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.21:kotlin-stdlib-jdk7-1.3.21.jar:a87875604fd42140da6938ae4d35ee61081f4482536efc6d2615b8b626a198af',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.21:kotlin-stdlib-jdk8-1.3.21.jar:5823ed66ac122a1c55442ebca5a209a843ccd87f562edc31a787f3d2e47f74d4',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.3.21:kotlin-stdlib-1.3.21.jar:38ba2370d9f06f50433e06b2ca775b94473c2e2785f410926079ab793c72b034',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',

bramble-api/build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.19"
+	implementation "com.google.dagger:dagger:2.22.1"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
 	testImplementation 'junit:junit:4.12'

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

@@ -4,8 +4,8 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.util.Arrays;
-import java.util.Comparator;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -15,8 +15,6 @@ import javax.annotation.concurrent.ThreadSafe;
 @NotNullByDefault
 public class Bytes implements Comparable<Bytes> {
 
-	public static final BytesComparator COMPARATOR = new BytesComparator();
-
 	private final byte[] bytes;
 
 	private int hashCode = -1;
@@ -38,20 +36,13 @@ public class Bytes implements Comparable<Bytes> {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 		return o instanceof Bytes && Arrays.equals(bytes, ((Bytes) o).bytes);
 	}
 
 	@Override
 	public int compareTo(Bytes other) {
-		byte[] aBytes = bytes, bBytes = other.bytes;
-		int length = Math.min(aBytes.length, bBytes.length);
-		for (int i = 0; i < length; i++) {
-			int aUnsigned = aBytes[i] & 0xFF, bUnsigned = bBytes[i] & 0xFF;
-			if (aUnsigned < bUnsigned) return -1;
-			if (aUnsigned > bUnsigned) return 1;
-		}
-		return aBytes.length - bBytes.length;
+		return compare(bytes, other.bytes);
 	}
 
 	@Override
@@ -60,11 +51,13 @@ public class Bytes implements Comparable<Bytes> {
 				"(" + StringUtils.toHexString(getBytes()) + ")";
 	}
 
-	public static class BytesComparator implements Comparator<Bytes> {
-
-		@Override
-		public int compare(Bytes a, Bytes b) {
-			return a.compareTo(b);
+	public static int compare(byte[] a, byte[] b) {
+		int length = Math.min(a.length, b.length);
+		for (int i = 0; i < length; i++) {
+			int aUnsigned = a[i] & 0xFF, bUnsigned = b[i] & 0xFF;
+			if (aUnsigned < bUnsigned) return -1;
+			if (aUnsigned > bUnsigned) return 1;
 		}
+		return a.length - b.length;
 	}
 }

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

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api;
+
+/**
+ * Interface for specifying which features are enabled in a build.
+ */
+public interface FeatureFlags {
+
+	boolean shouldEnableImageAttachments();
+
+	boolean shouldEnableRemoteContacts();
+}

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

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface Predicate<T> {
+
+	boolean test(T t);
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.api;
+
+/**
+ * Thrown when data being parsed uses a protocol or format version that is not
+ * supported.
+ */
+public class UnsupportedVersionException extends FormatException {
+
+	private final boolean tooOld;
+
+	public UnsupportedVersionException(boolean tooOld) {
+		this.tooOld = tooOld;
+	}
+
+	public boolean isTooOld() {
+		return tooOld;
+	}
+}

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

@@ -33,7 +33,8 @@ public abstract class BdfIncomingMessageHook implements IncomingMessageHook {
 	/**
 	 * Called once for each incoming message that passes validation.
 	 *
-	 * @return whether or not this message should be shared
+	 * @param txn A read-write transaction
+	 * @return Whether or not this message should be shared
 	 * @throws DbException Should only be used for real database errors.
 	 * If this is thrown, delivery will be attempted again at next startup,
 	 * whereas if a FormatException is thrown, the message will be permanently

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

@@ -1,6 +1,8 @@
 package org.briarproject.bramble.api.client;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.DbException;
@@ -23,7 +25,10 @@ public interface ClientHelper {
 			throws DbException, FormatException;
 
 	void addLocalMessage(Transaction txn, Message m, BdfDictionary metadata,
-			boolean shared) throws DbException, FormatException;
+			boolean shared, boolean temporary)
+			throws DbException, FormatException;
+
+	Message createMessage(GroupId g, long timestamp, byte[] body);
 
 	Message createMessage(GroupId g, long timestamp, BdfList body)
 			throws FormatException;
@@ -96,14 +101,18 @@ public interface ClientHelper {
 
 	BdfList toList(Author a);
 
-	byte[] sign(String label, BdfList toSign, byte[] privateKey)
+	byte[] sign(String label, BdfList toSign, PrivateKey privateKey)
 			throws FormatException, GeneralSecurityException;
 
 	void verifySignature(byte[] signature, String label, BdfList signed,
-			byte[] publicKey) throws FormatException, GeneralSecurityException;
+			PublicKey publicKey)
+			throws FormatException, GeneralSecurityException;
 
 	Author parseAndValidateAuthor(BdfList author) throws FormatException;
 
+	PublicKey parseAndValidateAgreementPublicKey(byte[] publicKeyBytes)
+			throws FormatException;
+
 	TransportProperties parseAndValidateTransportProperties(
 			BdfDictionary properties) throws FormatException;
 

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.contact;
 
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -19,10 +20,13 @@ public class Contact {
 	private final AuthorId localAuthorId;
 	@Nullable
 	private final String alias;
-	private final boolean verified, active;
+	@Nullable
+	private final PublicKey handshakePublicKey;
+	private final boolean verified;
 
 	public Contact(ContactId id, Author author, AuthorId localAuthorId,
-			@Nullable String alias, boolean verified, boolean active) {
+			@Nullable String alias, @Nullable PublicKey handshakePublicKey,
+			boolean verified) {
 		if (alias != null) {
 			int aliasLength = toUtf8(alias).length;
 			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
@@ -32,8 +36,8 @@ public class Contact {
 		this.author = author;
 		this.localAuthorId = localAuthorId;
 		this.alias = alias;
+		this.handshakePublicKey = handshakePublicKey;
 		this.verified = verified;
-		this.active = active;
 	}
 
 	public ContactId getId() {
@@ -53,12 +57,13 @@ public class Contact {
 		return alias;
 	}
 
-	public boolean isVerified() {
-		return verified;
+	@Nullable
+	public PublicKey getHandshakePublicKey() {
+		return handshakePublicKey;
 	}
 
-	public boolean isActive() {
-		return active;
+	public boolean isVerified() {
+		return verified;
 	}
 
 	@Override

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

@@ -1,20 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface ContactExchangeListener {
-
-	void contactExchangeSucceeded(Author remoteAuthor);
-
-	/**
-	 * The exchange failed because the contact already exists.
-	 */
-	void duplicateContact(Author remoteAuthor);
-
-	/**
-	 * A general failure.
-	 */
-	void contactExchangeFailed();
-}

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

@@ -0,0 +1,37 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.ContactExistsException;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+import java.io.IOException;
+
+@NotNullByDefault
+public interface ContactExchangeManager {
+
+	/**
+	 * Exchanges contact information with a remote peer and adds the peer
+	 * as a contact.
+	 *
+	 * @param alice Whether the local peer takes the role of Alice
+	 * @return The newly added contact
+	 * @throws ContactExistsException If the contact already exists
+	 */
+	Contact exchangeContacts(DuplexTransportConnection conn,
+			SecretKey masterKey, boolean alice, boolean verified)
+			throws IOException, DbException;
+
+	/**
+	 * Exchanges contact information with a remote peer and adds the peer
+	 * as a contact, replacing the given pending contact.
+	 *
+	 * @param alice Whether the local peer takes the role of Alice
+	 * @return The newly added contact
+	 * @throws ContactExistsException If the contact already exists
+	 */
+	Contact exchangeContacts(PendingContactId p, DuplexTransportConnection conn,
+			SecretKey masterKey, boolean alice, boolean verified)
+			throws IOException, DbException;
+}

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

@@ -1,48 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-
-/**
- * A task for conducting a contact information exchange with a remote peer.
- */
-@NotNullByDefault
-public interface ContactExchangeTask {
-
-	/**
-	 * The current version of the contact exchange protocol.
-	 */
-	byte PROTOCOL_VERSION = 1;
-
-	/**
-	 * 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.
-	 */
-	void startExchange(ContactExchangeListener listener,
-			LocalAuthor localAuthor, SecretKey masterSecret,
-			DuplexTransportConnection conn, TransportId transportId,
-			boolean alice);
-}

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.api.contact;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -28,7 +29,7 @@ public class ContactId {
 	}
 
 	@Override
-	public boolean equals(Object o) {
+	public boolean equals(@Nullable Object o) {
 		return o instanceof ContactId && id == ((ContactId) o).id;
 	}
 }

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

@@ -1,7 +1,11 @@
 package org.briarproject.bramble.api.contact;
 
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
@@ -9,6 +13,7 @@ import org.briarproject.bramble.api.identity.AuthorInfo;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import java.security.GeneralSecurityException;
 import java.util.Collection;
 
 import javax.annotation.Nullable;
@@ -25,60 +30,147 @@ public interface ContactManager {
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores transport keys for each transport, and returns an ID
-	 * for the contact.
+	 * derives and stores rotation mode transport keys for each transport, and
+	 * returns an ID for the contact.
 	 *
-	 * @param alice true if the local party is Alice
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			SecretKey master, long timestamp, boolean alice, boolean verified,
+			SecretKey rootKey, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
+	/**
+	 * Stores a contact associated with the given local and remote pseudonyms,
+	 * replacing the given pending contact, derives and stores handshake mode
+	 * and rotation mode transport keys for each transport, and returns an ID
+	 * for the contact.
+	 *
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
+	 * @throws GeneralSecurityException If the pending contact's handshake
+	 * public key is invalid
+	 */
+	ContactId addContact(Transaction txn, PendingContactId p, Author remote,
+			AuthorId local, SecretKey rootKey, long timestamp, boolean alice,
+			boolean verified, boolean active)
+			throws DbException, GeneralSecurityException;
+
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms
 	 * and returns an ID for the contact.
+	 *
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			boolean verified, boolean active) throws DbException;
+			boolean verified) throws DbException;
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores transport keys for each transport, and returns an ID
-	 * for the contact.
+	 * derives and stores rotation mode transport keys for each transport, and
+	 * returns an ID for the contact.
 	 *
-	 * @param alice true if the local party is Alice
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
 	 */
-	ContactId addContact(Author remote, AuthorId local, SecretKey master,
+	ContactId addContact(Author remote, AuthorId local, SecretKey rootKey,
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException;
 
+	/**
+	 * Returns the handshake link that needs to be sent to a contact we want
+	 * to add.
+	 */
+	String getHandshakeLink() throws DbException;
+
+	/**
+	 * Creates a {@link PendingContact} from the given handshake link and
+	 * alias, adds it to the database and returns it.
+	 *
+	 * @param link The handshake link received from the pending contact
+	 * @param alias The alias the user has given this pending contact
+	 * @throws UnsupportedVersionException If the link uses a format version
+	 * that is not supported
+	 * @throws FormatException If the link is invalid
+	 * @throws GeneralSecurityException If the pending contact's handshake
+	 * public key is invalid
+	 */
+	PendingContact addPendingContact(String link, String alias)
+			throws DbException, FormatException, GeneralSecurityException;
+
+	/**
+	 * Returns the pending contact with the given ID.
+	 */
+	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
+	/**
+	 * Returns a list of {@link PendingContact PendingContacts} and their
+	 * {@link PendingContactState states}.
+	 */
+	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
+			throws DbException;
+
+	/**
+	 * Removes a {@link PendingContact}.
+	 */
+	void removePendingContact(PendingContactId p) throws DbException;
+
 	/**
 	 * Returns the contact with the given ID.
 	 */
 	Contact getContact(ContactId c) throws DbException;
 
 	/**
-	 * Returns the contact with the given remoteAuthorId
-	 * that was added by the LocalAuthor with the given localAuthorId
+	 * Returns the contact with the given ID.
+	 */
+	Contact getContact(Transaction txn, ContactId c) throws DbException;
+
+	/**
+	 * Returns the contact with the given {@code remoteAuthorId}
+	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
 	 *
-	 * @throws org.briarproject.bramble.api.db.NoSuchContactException
+	 * @throws NoSuchContactException If the contact is not in the database
 	 */
 	Contact getContact(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
 
 	/**
-	 * Returns the contact with the given remoteAuthorId
-	 * that was added by the LocalAuthor with the given localAuthorId
+	 * Returns the contact with the given {@code remoteAuthorId}
+	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
 	 *
-	 * @throws org.briarproject.bramble.api.db.NoSuchContactException
+	 * @throws NoSuchContactException If the contact is not in the database
 	 */
 	Contact getContact(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Returns all active contacts.
+	 * Returns all contacts.
 	 */
-	Collection<Contact> getActiveContacts() throws DbException;
+	Collection<Contact> getContacts() throws DbException;
 
 	/**
 	 * Removes a contact and all associated state.
@@ -91,31 +183,27 @@ public interface ContactManager {
 	void removeContact(Transaction txn, ContactId c) throws DbException;
 
 	/**
-	 * Marks a contact as active or inactive.
-	 */
-	void setContactActive(Transaction txn, ContactId c, boolean active)
-			throws DbException;
-
-	/**
-	 * Sets an alias name for the contact or unsets it if alias is null.
+	 * Sets an alias for the contact or unsets it if {@code alias} is null.
 	 */
 	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Sets an alias name for the contact or unsets it if alias is null.
+	 * Sets an alias for the contact or unsets it if {@code alias} is null.
 	 */
 	void setContactAlias(ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Return true if a contact with this name and public key already exists
+	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Return true if a contact with this name and public key already exists
+	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
@@ -132,8 +220,20 @@ public interface ContactManager {
 
 	interface ContactHook {
 
+		/**
+		 * Called when a contact is being added.
+		 *
+		 * @param txn A read-write transaction
+		 * @param c The contact that is being added
+		 */
 		void addingContact(Transaction txn, Contact c) throws DbException;
 
+		/**
+		 * Called when a contact is being removed
+		 *
+		 * @param txn A read-write transaction
+		 * @param c The contact that is being removed
+		 */
 		void removingContact(Transaction txn, Contact c) throws DbException;
 	}
 }

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

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.api.contact;
+
+import java.util.regex.Pattern;
+
+public interface HandshakeLinkConstants {
+
+	/**
+	 * The current version of the handshake link format.
+	 */
+	int FORMAT_VERSION = 0;
+
+	/**
+	 * The length of a base32-encoded handshake link in bytes, excluding the
+	 * 'briar://' prefix.
+	 */
+	int BASE32_LINK_BYTES = 53;
+
+	/**
+	 * The length of a raw handshake link in bytes, before base32 encoding.
+	 */
+	int RAW_LINK_BYTES = 33;
+
+	/**
+	 * Regular expression for matching handshake links, including or excluding
+	 * the 'briar://' prefix.
+	 */
+	Pattern LINK_REGEX =
+			Pattern.compile("(briar://)?([a-z2-7]{" + BASE32_LINK_BYTES + "})");
+
+	/**
+	 * Label for hashing handshake public keys to calculate their identifiers.
+	 */
+	String ID_LABEL = "org.briarproject.bramble/HANDSHAKE_KEY_ID";
+}

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

@@ -0,0 +1,45 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.transport.StreamWriter;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+@NotNullByDefault
+public interface HandshakeManager {
+
+	/**
+	 * Handshakes with the given pending contact. Returns an ephemeral master
+	 * key authenticated with both parties' handshake key pairs and a flag
+	 * indicating whether the local peer is Alice or Bob.
+	 *
+	 * @param in An incoming stream for the handshake, which must be secured in
+	 * handshake mode
+	 * @param out An outgoing stream for the handshake, which must be secured
+	 * in handshake mode
+	 */
+	HandshakeResult handshake(PendingContactId p, InputStream in,
+			StreamWriter out) throws DbException, IOException;
+
+	class HandshakeResult {
+
+		private final SecretKey masterKey;
+		private final boolean alice;
+
+		public HandshakeResult(SecretKey masterKey, boolean alice) {
+			this.masterKey = masterKey;
+			this.alice = alice;
+		}
+
+		public SecretKey getMasterKey() {
+			return masterKey;
+		}
+
+		public boolean isAlice() {
+			return alice;
+		}
+	}
+}

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

@@ -0,0 +1,51 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class PendingContact {
+
+	private final PendingContactId id;
+	private final PublicKey publicKey;
+	private final String alias;
+	private final long timestamp;
+
+	public PendingContact(PendingContactId id, PublicKey publicKey,
+			String alias, long timestamp) {
+		this.id = id;
+		this.publicKey = publicKey;
+		this.alias = alias;
+		this.timestamp = timestamp;
+	}
+
+	public PendingContactId getId() {
+		return id;
+	}
+
+	public PublicKey getPublicKey() {
+		return publicKey;
+	}
+
+	public String getAlias() {
+		return alias;
+	}
+
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof PendingContact &&
+				id.equals(((PendingContact) o).id);
+	}
+}

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

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.UniqueId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a
+ * {@link PendingContact}.
+ */
+@ThreadSafe
+@NotNullByDefault
+public class PendingContactId extends UniqueId {
+
+	public PendingContactId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof PendingContactId && super.equals(o);
+	}
+}

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

@@ -0,0 +1,10 @@
+package org.briarproject.bramble.api.contact;
+
+public enum PendingContactState {
+
+	WAITING_FOR_CONNECTION,
+	OFFLINE,
+	CONNECTING,
+	ADDING_CONTACT,
+	FAILED
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactAddedEvent.java

@@ -14,18 +14,18 @@ import javax.annotation.concurrent.Immutable;
 public class ContactAddedEvent extends Event {
 
 	private final ContactId contactId;
-	private final boolean active;
+	private final boolean verified;
 
-	public ContactAddedEvent(ContactId contactId, boolean active) {
+	public ContactAddedEvent(ContactId contactId, boolean verified) {
 		this.contactId = contactId;
-		this.active = active;
+		this.verified = verified;
 	}
 
 	public ContactId getContactId() {
 		return contactId;
 	}
 
-	public boolean isActive() {
-		return active;
+	public boolean isVerified() {
+		return verified;
 	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactStatusChangedEvent.java

@@ -1,31 +0,0 @@
-package org.briarproject.bramble.api.contact.event;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.concurrent.Immutable;
-
-/**
- * An event that is broadcast when a contact is marked active or inactive.
- */
-@Immutable
-@NotNullByDefault
-public class ContactStatusChangedEvent extends Event {
-
-	private final ContactId contactId;
-	private final boolean active;
-
-	public ContactStatusChangedEvent(ContactId contactId, boolean active) {
-		this.contactId = contactId;
-		this.active = active;
-	}
-
-	public ContactId getContactId() {
-		return contactId;
-	}
-
-	public boolean isActive() {
-		return active;
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/PendingContactAddedEvent.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.PendingContact;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a pending contact is added.
+ */
+@Immutable
+@NotNullByDefault
+public class PendingContactAddedEvent extends Event {
+
+	private final PendingContact pendingContact;
+
+	public PendingContactAddedEvent(PendingContact pendingContact) {
+		this.pendingContact = pendingContact;
+	}
+
+	public PendingContact getPendingContact() {
+		return pendingContact;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/PendingContactRemovedEvent.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a pending contact is removed.
+ */
+@Immutable
+@NotNullByDefault
+public class PendingContactRemovedEvent extends Event {
+
+	private final PendingContactId id;
+
+	public PendingContactRemovedEvent(PendingContactId id) {
+		this.id = id;
+	}
+
+	public PendingContactId getId() {
+		return id;
+	}
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/PendingContactStateChangedEvent.java

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.contact.PendingContactState;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a pending contact's state is changed.
+ */
+@Immutable
+@NotNullByDefault
+public class PendingContactStateChangedEvent extends Event {
+
+	private final PendingContactId id;
+	private final PendingContactState state;
+
+	public PendingContactStateChangedEvent(PendingContactId id,
+			PendingContactState state) {
+		this.id = id;
+		this.state = state;
+	}
+
+	public PendingContactId getId() {
+		return id;
+	}
+
+	public PendingContactState getPendingContactState() {
+		return state;
+	}
+
+}

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

@@ -0,0 +1,30 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
+
+/**
+ * Type-safe wrapper for a private key used for key agreement.
+ */
+@Immutable
+@NotNullByDefault
+public class AgreementPrivateKey extends Bytes implements PrivateKey {
+
+	public AgreementPrivateKey(byte[] encoded) {
+		super(encoded);
+	}
+
+	@Override
+	public String getKeyType() {
+		return KEY_TYPE_AGREEMENT;
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

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

@@ -0,0 +1,35 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_AGREEMENT_PUBLIC_KEY_BYTES;
+
+/**
+ * Type-safe wrapper for a public key used for key agreement.
+ */
+@Immutable
+@NotNullByDefault
+public class AgreementPublicKey extends Bytes implements PublicKey {
+
+	public AgreementPublicKey(byte[] encoded) {
+		super(encoded);
+		if (encoded.length == 0 ||
+				encoded.length > MAX_AGREEMENT_PUBLIC_KEY_BYTES) {
+			throw new IllegalArgumentException();
+		}
+	}
+
+	@Override
+	public String getKeyType() {
+		return KEY_TYPE_AGREEMENT;
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

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

@@ -27,54 +27,78 @@ public interface CryptoComponent {
 	/**
 	 * Derives another secret key from the given secret key.
 	 *
-	 * @param label a namespaced label indicating the purpose of the derived
+	 * @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
+	 * @param inputs Additional inputs that will be included in the derivation
+	 * of the key
 	 */
 	SecretKey deriveKey(String label, SecretKey k, byte[]... inputs);
 
 	/**
-	 * Derives a common shared secret from two public keys and one of the
-	 * corresponding private keys.
+	 * Derives a shared secret from two key pairs.
 	 *
-	 * @param label a namespaced label indicating the purpose of this shared
+	 * @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
+	 * @param theirPublicKey The public key of the remote party
+	 * @param ourKeyPair The key pair of the local party
+	 * @param inputs Additional inputs that will be included in the derivation
+	 * of the shared secret
+	 * @return The shared secret
 	 */
 	SecretKey deriveSharedSecret(String label, PublicKey theirPublicKey,
 			KeyPair ourKeyPair, byte[]... inputs)
 			throws GeneralSecurityException;
 
+	/**
+	 * Derives a shared secret from two static and two ephemeral key pairs.
+	 *
+	 * @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 theirStaticPublicKey The static public key of the remote party
+	 * @param theirEphemeralPublicKey The ephemeral public key of the remote
+	 * party
+	 * @param ourStaticKeyPair The static key pair of the local party
+	 * @param ourEphemeralKeyPair The ephemeral key pair of the local party
+	 * @param alice True if the local party is Alice
+	 * @param inputs Additional inputs that will be included in the
+	 * derivation of the shared secret
+	 * @return The shared secret
+	 */
+	SecretKey deriveSharedSecret(String label, PublicKey theirStaticPublicKey,
+			PublicKey theirEphemeralPublicKey, KeyPair ourStaticKeyPair,
+			KeyPair ourEphemeralKeyPair, boolean alice, byte[]... inputs)
+			throws GeneralSecurityException;
+
 	/**
 	 * Signs the given byte[] with the given private key.
 	 *
-	 * @param label a namespaced label indicating the purpose of this
+	 * @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)
+	byte[] sign(String label, byte[] toSign, PrivateKey privateKey)
 			throws GeneralSecurityException;
 
 	/**
 	 * Verifies that the given signature is valid for the signed data
 	 * and the given public key.
 	 *
-	 * @param label a namespaced label indicating the purpose of this
+	 * @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.
+	 * @return True if the signature was valid, false otherwise.
 	 */
 	boolean verifySignature(byte[] signature, String label, byte[] signed,
-			byte[] publicKey) throws GeneralSecurityException;
+			PublicKey publicKey) throws GeneralSecurityException;
 
 	/**
 	 * Returns the hash of 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 hash, to
+	 * @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
 	 */
@@ -85,7 +109,7 @@ public interface CryptoComponent {
 	 * 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
+	 * @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
 	 */
@@ -95,10 +119,10 @@ public interface CryptoComponent {
 	 * Verifies that the given message authentication code is valid for the
 	 * given secret key and inputs.
 	 *
-	 * @param label a namespaced label indicating the purpose of this MAC, to
+	 * @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
-	 * @return true if the MAC was valid, false otherwise.
+	 * @return True if the MAC was valid, false otherwise.
 	 */
 	boolean verifyMac(byte[] mac, String label, SecretKey macKey,
 			byte[]... inputs);

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

@@ -7,11 +7,21 @@ public interface CryptoConstants {
 	 */
 	int MAX_AGREEMENT_PUBLIC_KEY_BYTES = 32;
 
+	/**
+	 * The key type for agreement key pairs.
+	 */
+	String KEY_TYPE_AGREEMENT = "Curve25519";
+
 	/**
 	 * The maximum length of a signature public key in bytes.
 	 */
 	int MAX_SIGNATURE_PUBLIC_KEY_BYTES = 32;
 
+	/**
+	 * The key type for signature key pairs.
+	 */
+	String KEY_TYPE_SIGNATURE = "Ed25519";
+
 	/**
 	 * The maximum length of a signature in bytes.
 	 */

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

@@ -2,7 +2,7 @@ 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
+ * https://code.briarproject.org/briar/briar-spec/blob/master/protocols/BQP.md
  */
 public interface KeyAgreementCrypto {
 

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

@@ -15,6 +15,8 @@ public class KeyPair {
 	private final PrivateKey privateKey;
 
 	public KeyPair(PublicKey publicKey, PrivateKey privateKey) {
+		if (!publicKey.getKeyType().equals(privateKey.getKeyType()))
+			throw new IllegalArgumentException();
 		this.publicKey = publicKey;
 		this.privateKey = privateKey;
 	}

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

@@ -8,6 +8,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 @NotNullByDefault
 public interface PrivateKey {
 
+	/**
+	 * Returns the type of this key pair.
+	 */
+	String getKeyType();
+
 	/**
 	 * Returns the encoded representation of this key.
 	 */

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

@@ -8,6 +8,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 @NotNullByDefault
 public interface PublicKey {
 
+	/**
+	 * Returns the type of this key pair.
+	 */
+	String getKeyType();
+
 	/**
 	 * Returns the encoded representation of this key.
 	 */

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

@@ -0,0 +1,30 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
+
+/**
+ * Type-safe wrapper for a public key used for signing.
+ */
+@Immutable
+@NotNullByDefault
+public class SignaturePrivateKey extends Bytes implements PrivateKey {
+
+	public SignaturePrivateKey(byte[] bytes) {
+		super(bytes);
+	}
+
+	@Override
+	public String getKeyType() {
+		return KEY_TYPE_SIGNATURE;
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

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

@@ -0,0 +1,35 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_PUBLIC_KEY_BYTES;
+
+/**
+ * Type-safe wrapper for a public key used for verifying signatures.
+ */
+@Immutable
+@NotNullByDefault
+public class SignaturePublicKey extends Bytes implements PublicKey {
+
+	public SignaturePublicKey(byte[] encoded) {
+		super(encoded);
+		if (encoded.length == 0 ||
+				encoded.length > MAX_SIGNATURE_PUBLIC_KEY_BYTES) {
+			throw new IllegalArgumentException();
+		}
+	}
+
+	@Override
+	public String getKeyType() {
+		return KEY_TYPE_SIGNATURE;
+	}
+
+	@Override
+	public byte[] getEncoded() {
+		return getBytes();
+	}
+}

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

@@ -3,27 +3,61 @@ package org.briarproject.bramble.api.crypto;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
+import java.security.GeneralSecurityException;
+
 /**
  * Crypto operations for the transport security protocol - see
- * https://code.briarproject.org/akwizgran/briar-spec/blob/master/protocols/BTP.md
+ * https://code.briarproject.org/briar/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.
-	 * @param active whether the keys are usable for outgoing streams.
+	 * Returns true if the local peer is Alice.
 	 */
-	TransportKeys deriveTransportKeys(TransportId t, SecretKey master,
-			long rotationPeriod, boolean alice, boolean active);
+	boolean isAlice(PublicKey theirHandshakePublicKey,
+			KeyPair ourHandshakeKeyPair);
 
 	/**
-	 * 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.
+	 * Derives the static master key shared with a contact or pending contact.
 	 */
-	TransportKeys rotateTransportKeys(TransportKeys k, long rotationPeriod);
+	SecretKey deriveStaticMasterKey(PublicKey theirHandshakePublicKey,
+			KeyPair ourHandshakeKeyPair) throws GeneralSecurityException;
+
+	/**
+	 * Derives the handshake mode root key from the static master key. To
+	 * prevent tag reuse, separate root keys are derived for contacts and
+	 * pending contacts.
+	 *
+	 * @param pendingContact Whether the static master key is shared with a
+	 * pending contact or a contact
+	 */
+	SecretKey deriveHandshakeRootKey(SecretKey staticMasterKey,
+			boolean pendingContact);
+
+	/**
+	 * Derives initial rotation mode transport keys for the given transport in
+	 * the given time period from the given root key.
+	 *
+	 * @param alice Whether the keys are for use by Alice or Bob
+	 * @param active Whether the keys are usable for outgoing streams
+	 */
+	TransportKeys deriveRotationKeys(TransportId t, SecretKey rootKey,
+			long timePeriod, boolean alice, boolean active);
+
+	/**
+	 * Derives handshake keys for the given transport in the given time period
+	 * from the given root key.
+	 *
+	 * @param alice Whether the keys are for use by Alice or Bob
+	 */
+	TransportKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
+			long timePeriod, boolean alice);
+
+	/**
+	 * Updates the given transport keys to the given time period. If the keys
+	 * are for the given period or any later period they are not updated.
+	 */
+	TransportKeys updateTransportKeys(TransportKeys k, long timePeriod);
 
 	/**
 	 * Encodes the pseudo-random tag that is used to recognise a stream.

bramble-api/src/main/java/org/briarproject/bramble/api/db/CommitAction.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.db;
+
+import org.briarproject.bramble.api.event.EventExecutor;
+
+/**
+ * An action that's taken when a {@link Transaction} is committed.
+ */
+public interface CommitAction {
+
+	void accept(Visitor visitor);
+
+	interface Visitor {
+
+		@EventExecutor
+		void visit(EventAction a);
+
+		@EventExecutor
+		void visit(TaskAction a);
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/ContactExistsException.java

@@ -1,8 +1,27 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+
 /**
  * Thrown when a duplicate contact is added to the database. This exception may
  * occur due to concurrent updates and does not indicate a database error.
  */
 public class ContactExistsException extends DbException {
+
+	private final AuthorId local;
+	private final Author remote;
+
+	public ContactExistsException(AuthorId local, Author remote) {
+		this.local = local;
+		this.remote = remote;
+	}
+
+	public AuthorId getLocalAuthorId() {
+		return local;
+	}
+
+	public Author getRemoteAuthor() {
+		return remote;
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -2,10 +2,14 @@ package org.briarproject.bramble.api.db;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContact;
+import org.briarproject.bramble.api.contact.PendingContactId;
+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.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.identity.Identity;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.settings.Settings;
@@ -20,11 +24,12 @@ import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.validation.MessageState;
-import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
+import org.briarproject.bramble.api.transport.TransportKeySet;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -34,7 +39,7 @@ import javax.annotation.Nullable;
  * to other components.
  */
 @NotNullByDefault
-public interface DatabaseComponent {
+public interface DatabaseComponent extends TransactionManager {
 
 	/**
 	 * Opens the database and returns true if the database already existed.
@@ -52,56 +57,12 @@ public interface DatabaseComponent {
 	 */
 	void close() throws DbException;
 
-	/**
-	 * Starts a new transaction and returns an object representing it.
-	 * <p/>
-	 * This method acquires locks, so it must not be called while holding a
-	 * lock.
-	 *
-	 * @param readOnly true if the transaction will only be used for reading.
-	 */
-	Transaction startTransaction(boolean readOnly) throws DbException;
-
-	/**
-	 * Commits a transaction to the database.
-	 */
-	void commitTransaction(Transaction txn) throws DbException;
-
-	/**
-	 * Ends a transaction. If the transaction has not been committed,
-	 * it will be aborted. If the transaction has been committed,
-	 * any events attached to the transaction are broadcast.
-	 * The database lock will be released in either case.
-	 */
-	void endTransaction(Transaction txn);
-
-	/**
-	 * Runs the given task within a transaction.
-	 */
-	<E extends Exception> void transaction(boolean readOnly,
-			DbRunnable<E> task) throws DbException, E;
-
-	/**
-	 * Runs the given task within a transaction and returns the result of the
-	 * task.
-	 */
-	<R, E extends Exception> R transactionWithResult(boolean readOnly,
-			DbCallable<R, E> task) throws DbException, E;
-
-	/**
-	 * Runs the given task within a transaction and returns the result of the
-	 * task, which may be null.
-	 */
-	@Nullable
-	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,
-			NullableDbCallable<R, E> task) throws DbException, E;
-
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
 	 * and returns an ID for the contact.
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			boolean verified, boolean active) throws DbException;
+			@Nullable PublicKey handshake, boolean verified) throws DbException;
 
 	/**
 	 * Stores a group.
@@ -109,15 +70,21 @@ public interface DatabaseComponent {
 	void addGroup(Transaction txn, Group g) throws DbException;
 
 	/**
-	 * Stores a local pseudonym.
+	 * Stores an identity.
 	 */
-	void addLocalAuthor(Transaction txn, LocalAuthor a) throws DbException;
+	void addIdentity(Transaction txn, Identity i) throws DbException;
 
 	/**
 	 * Stores a local message.
 	 */
 	void addLocalMessage(Transaction txn, Message m, Metadata meta,
-			boolean shared) throws DbException;
+			boolean shared, boolean temporary) throws DbException;
+
+	/**
+	 * Stores a pending contact.
+	 */
+	void addPendingContact(Transaction txn, PendingContact p)
+			throws DbException;
 
 	/**
 	 * Stores a transport.
@@ -129,25 +96,46 @@ public interface DatabaseComponent {
 	 * Stores the given transport keys for the given contact and returns a
 	 * key set ID.
 	 */
-	KeySetId addTransportKeys(Transaction txn, ContactId c,
+	KeySetId addTransportKeys(Transaction txn, ContactId c, TransportKeys k)
+			throws DbException;
+
+	/**
+	 * Stores the given transport keys for the given pending contact and
+	 * returns a key set ID.
+	 */
+	KeySetId addTransportKeys(Transaction txn, PendingContactId p,
 			TransportKeys k) throws DbException;
 
 	/**
 	 * Returns true if the database contains the given contact for the given
 	 * local pseudonym.
+	 * <p/>
+	 * Read-only.
 	 */
 	boolean containsContact(Transaction txn, AuthorId remote, AuthorId local)
 			throws DbException;
 
 	/**
 	 * Returns true if the database contains the given group.
+	 * <p/>
+	 * Read-only.
 	 */
 	boolean containsGroup(Transaction txn, GroupId g) throws DbException;
 
 	/**
-	 * Returns true if the database contains the given local author.
+	 * Returns true if the database contains an identity for the given
+	 * pseudonym.
+	 * <p/>
+	 * Read-only.
 	 */
-	boolean containsLocalAuthor(Transaction txn, AuthorId local)
+	boolean containsIdentity(Transaction txn, AuthorId a) throws DbException;
+
+	/**
+	 * Returns true if the database contains the given pending contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	boolean containsPendingContact(Transaction txn, PendingContactId p)
 			throws DbException;
 
 	/**
@@ -235,7 +223,7 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<ContactId> getContacts(Transaction txn, AuthorId a)
+	Collection<ContactId> getContacts(Transaction txn, AuthorId local)
 			throws DbException;
 
 	/**
@@ -270,18 +258,18 @@ public interface DatabaseComponent {
 			throws DbException;
 
 	/**
-	 * Returns the local pseudonym with the given ID.
+	 * Returns the identity for the local pseudonym with the given ID.
 	 * <p/>
 	 * Read-only.
 	 */
-	LocalAuthor getLocalAuthor(Transaction txn, AuthorId a) throws DbException;
+	Identity getIdentity(Transaction txn, AuthorId a) throws DbException;
 
 	/**
-	 * Returns all local pseudonyms.
+	 * Returns the identities for all local pseudonyms.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<LocalAuthor> getLocalAuthors(Transaction txn) throws DbException;
+	Collection<Identity> getIdentities(Transaction txn) throws DbException;
 
 	/**
 	 * Returns the message with the given ID.
@@ -417,6 +405,22 @@ public interface DatabaseComponent {
 	 */
 	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns the pending contact with the given ID.
+	 * <p/>
+	 * Read-only.
+	 */
+	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
+	/**
+	 * Returns all pending contacts.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<PendingContact> getPendingContacts(Transaction txn)
+			throws DbException;
+
 	/**
 	 * Returns all settings in the given namespace.
 	 * <p/>
@@ -424,12 +428,19 @@ public interface DatabaseComponent {
 	 */
 	Settings getSettings(Transaction txn, String namespace) throws DbException;
 
+	/**
+	 * Returns the versions of the sync protocol supported by the given contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	List<Byte> getSyncVersions(Transaction txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns all transport keys for the given transport.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<KeySet> getTransportKeys(Transaction txn, TransportId t)
+	Collection<TransportKeySet> getTransportKeys(Transaction txn, TransportId t)
 			throws DbException;
 
 	/**
@@ -492,15 +503,27 @@ public interface DatabaseComponent {
 	void removeGroup(Transaction txn, Group g) throws DbException;
 
 	/**
-	 * Removes a local pseudonym (and all associated state) from the database.
+	 * Removes an identity (and all associated state) from the database.
 	 */
-	void removeLocalAuthor(Transaction txn, AuthorId a) throws DbException;
+	void removeIdentity(Transaction txn, AuthorId a) throws DbException;
 
 	/**
 	 * Removes a message (and all associated state) from the database.
 	 */
 	void removeMessage(Transaction txn, MessageId m) throws DbException;
 
+	/**
+	 * Removes a pending contact (and all associated state) from the database.
+	 */
+	void removePendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
+	/**
+	 * Removes all temporary messages (and all associated state) from the
+	 * database.
+	 */
+	void removeTemporaryMessages(Transaction txn) throws DbException;
+
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */
@@ -517,12 +540,6 @@ public interface DatabaseComponent {
 	 */
 	void setContactVerified(Transaction txn, ContactId c) throws DbException;
 
-	/**
-	 * Marks the given contact as active or inactive.
-	 */
-	void setContactActive(Transaction txn, ContactId c, boolean active)
-			throws DbException;
-
 	/**
 	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */
@@ -535,6 +552,11 @@ public interface DatabaseComponent {
 	void setGroupVisibility(Transaction txn, ContactId c, GroupId g,
 			Visibility v) throws DbException;
 
+	/**
+	 * Marks the given message as permanent, i.e. not temporary.
+	 */
+	void setMessagePermanent(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -553,11 +575,23 @@ public interface DatabaseComponent {
 			Collection<MessageId> dependencies) throws DbException;
 
 	/**
-	 * Sets the reordering window for the given key set and transport in the
-	 * given rotation period.
+	 * Sets the handshake key pair for the identity with the given ID.
+	 */
+	void setHandshakeKeyPair(Transaction txn, AuthorId local,
+			PublicKey publicKey, PrivateKey privateKey) throws DbException;
+
+	/**
+	 * Sets the reordering window for the given transport keys in the given
+	 * time period.
 	 */
 	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
-			long rotationPeriod, long base, byte[] bitmap) throws DbException;
+			long timePeriod, long base, byte[] bitmap) throws DbException;
+
+	/**
+	 * Sets the versions of the sync protocol supported by the given contact.
+	 */
+	void setSyncVersions(Transaction txn, ContactId c, List<Byte> supported)
+			throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
@@ -568,6 +602,6 @@ public interface DatabaseComponent {
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
-	void updateTransportKeys(Transaction txn, Collection<KeySet> keys)
+	void updateTransportKeys(Transaction txn, Collection<TransportKeySet> keys)
 			throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseConfig.java

@@ -10,6 +10,4 @@ public interface DatabaseConfig {
 	File getDatabaseDirectory();
 
 	File getDatabaseKeyDirectory();
-
-	long getMaxSize();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/EventAction.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.db;
+
+import org.briarproject.bramble.api.event.Event;
+
+/**
+ * A {@link CommitAction} that broadcasts an event.
+ */
+public class EventAction implements CommitAction {
+
+	private final Event event;
+
+	EventAction(Event event) {
+		this.event = event;
+	}
+
+	public Event getEvent() {
+		return event;
+	}
+
+	@Override
+	public void accept(Visitor visitor) {
+		visitor.visit(this);
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchIdentityException.java

@@ -1,9 +1,9 @@
 package org.briarproject.bramble.api.db;
 
 /**
- * Thrown when a database operation is attempted for a pseudonym that is not in
+ * Thrown when a database operation is attempted for an identity that is not in
  * the database. This exception may occur due to concurrent updates and does
  * not indicate a database error.
  */
-public class NoSuchLocalAuthorException extends DbException {
+public class NoSuchIdentityException extends DbException {
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/NoSuchPendingContactException.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when a database operation is attempted for a pending contact that is
+ * not in the database. This exception may occur due to concurrent updates and
+ * does not indicate a database error.
+ */
+public class NoSuchPendingContactException extends DbException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/PendingContactExistsException.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when a duplicate pending contact is added to the database. This
+ * exception may occur due to concurrent updates and does not indicate a
+ * database error.
+ */
+public class PendingContactExistsException extends DbException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/TaskAction.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.db;
+
+import org.briarproject.bramble.api.event.EventExecutor;
+
+/**
+ * A {@link CommitAction} that submits a task to the {@link EventExecutor}.
+ */
+public class TaskAction implements CommitAction {
+
+	private final Runnable task;
+
+	TaskAction(Runnable task) {
+		this.task = task;
+	}
+
+	public Runnable getTask() {
+		return task;
+	}
+
+	@Override
+	public void accept(Visitor visitor) {
+		visitor.visit(this);
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/Transaction.java

@@ -1,13 +1,15 @@
 package org.briarproject.bramble.api.db;
 
 import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventExecutor;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
+import static java.util.Collections.emptyList;
+
 /**
  * A wrapper around a database transaction. Transactions are not thread-safe.
  */
@@ -17,7 +19,7 @@ public class Transaction {
 	private final Object txn;
 	private final boolean readOnly;
 
-	private List<Event> events = null;
+	private List<CommitAction> actions = null;
 	private boolean committed = false;
 
 	public Transaction(Object txn, boolean readOnly) {
@@ -42,19 +44,27 @@ public class Transaction {
 
 	/**
 	 * Attaches an event to be broadcast when the transaction has been
-	 * committed.
+	 * committed. The event will be broadcast on the {@link EventExecutor}.
 	 */
 	public void attach(Event e) {
-		if (events == null) events = new ArrayList<>();
-		events.add(e);
+		if (actions == null) actions = new ArrayList<>();
+		actions.add(new EventAction(e));
 	}
 
 	/**
-	 * Returns any events attached to the transaction.
+	 * Attaches a task to be executed when the transaction has been
+	 * committed. The task will be run on the {@link EventExecutor}.
 	 */
-	public List<Event> getEvents() {
-		if (events == null) return Collections.emptyList();
-		return events;
+	public void attach(Runnable r) {
+		if (actions == null) actions = new ArrayList<>();
+		actions.add(new TaskAction(r));
+	}
+
+	/**
+	 * Returns any actions attached to the transaction.
+	 */
+	public List<CommitAction> getActions() {
+		return actions == null ? emptyList() : actions;
 	}
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/db/TransactionManager.java

@@ -0,0 +1,54 @@
+package org.briarproject.bramble.api.db;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface TransactionManager {
+
+	/**
+	 * Starts a new transaction and returns an object representing it.
+	 * <p/>
+	 * This method acquires locks, so it must not be called while holding a
+	 * lock.
+	 *
+	 * @param readOnly true if the transaction will only be used for reading.
+	 */
+	Transaction startTransaction(boolean readOnly) throws DbException;
+
+	/**
+	 * Commits a transaction to the database.
+	 */
+	void commitTransaction(Transaction txn) throws DbException;
+
+	/**
+	 * Ends a transaction. If the transaction has not been committed,
+	 * it will be aborted. If the transaction has been committed,
+	 * any events attached to the transaction are broadcast.
+	 * The database lock will be released in either case.
+	 */
+	void endTransaction(Transaction txn);
+
+	/**
+	 * Runs the given task within a transaction.
+	 */
+	<E extends Exception> void transaction(boolean readOnly,
+			DbRunnable<E> task) throws DbException, E;
+
+	/**
+	 * Runs the given task within a transaction and returns the result of the
+	 * task.
+	 */
+	<R, E extends Exception> R transactionWithResult(boolean readOnly,
+			DbCallable<R, E> task) throws DbException, E;
+
+	/**
+	 * Runs the given task within a transaction and returns the result of the
+	 * task, which may be null.
+	 */
+	@Nullable
+	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,
+			NullableDbCallable<R, E> task) throws DbException, E;
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventBus.java

@@ -16,7 +16,8 @@ public interface EventBus {
 	void removeListener(EventListener l);
 
 	/**
-	 * Notifies all listeners of an event.
+	 * Asynchronously notifies all listeners of an event. Listeners are
+	 * notified on the {@link EventExecutor}.
 	 */
 	void broadcast(Event e);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventExecutor.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.event;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import javax.inject.Qualifier;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+/**
+ * Annotation for injecting the executor for broadcasting events and running
+ * tasks that need to run in a defined order with respect to events. Also used
+ * for annotating methods that should run on the event executor.
+ * <p>
+ * The contract of this executor is that tasks are run in the order they're
+ * submitted, tasks are not run concurrently, and submitting a task will never
+ * block. Tasks must not block. Tasks submitted during shutdown are discarded.
+ */
+@Qualifier
+@Target({FIELD, METHOD, PARAMETER})
+@Retention(RUNTIME)
+public @interface EventExecutor {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventListener.java

@@ -12,5 +12,6 @@ public interface EventListener {
 	 * Called when an event is broadcast. Implementations of this method must
 	 * not block.
 	 */
+	@EventExecutor
 	void eventOccurred(Event e);
 }

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

@@ -1,13 +1,14 @@
 package org.briarproject.bramble.api.identity;
 
 import org.briarproject.bramble.api.Nameable;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
 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.util.StringUtils.toUtf8;
 
 /**
  * A pseudonym for a user.
@@ -24,14 +25,14 @@ public class Author implements Nameable {
 	private final AuthorId id;
 	private final int formatVersion;
 	private final String name;
-	private final byte[] publicKey;
+	private final PublicKey publicKey;
 
 	public Author(AuthorId id, int formatVersion, String name,
-			byte[] publicKey) {
-		int nameLength = StringUtils.toUtf8(name).length;
+			PublicKey publicKey) {
+		int nameLength = toUtf8(name).length;
 		if (nameLength == 0 || nameLength > MAX_AUTHOR_NAME_LENGTH)
 			throw new IllegalArgumentException();
-		if (publicKey.length == 0 || publicKey.length > MAX_PUBLIC_KEY_LENGTH)
+		if (!publicKey.getKeyType().equals(KEY_TYPE_SIGNATURE))
 			throw new IllegalArgumentException();
 		this.id = id;
 		this.formatVersion = formatVersion;
@@ -63,7 +64,7 @@ public class Author implements Nameable {
 	/**
 	 * Returns the public key used to verify the pseudonym's signatures.
 	 */
-	public byte[] getPublicKey() {
+	public PublicKey getPublicKey() {
 		return publicKey;
 	}
 

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.identity;
 
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 @NotNullByDefault
@@ -9,23 +10,16 @@ public interface AuthorFactory {
 	 * Creates an author with the current format version and the given name and
 	 * public key.
 	 */
-	Author createAuthor(String name, byte[] publicKey);
+	Author createAuthor(String name, PublicKey publicKey);
 
 	/**
 	 * Creates an author with the given format version, name and public key.
 	 */
-	Author createAuthor(int formatVersion, String name, byte[] publicKey);
+	Author createAuthor(int formatVersion, String name, PublicKey publicKey);
 
 	/**
 	 * Creates a local author with the current format version and the given
-	 * name and keys.
+	 * name.
 	 */
-	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);
+	LocalAuthor createLocalAuthor(String name);
 }

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

@@ -0,0 +1,88 @@
+package org.briarproject.bramble.api.identity;
+
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
+
+@Immutable
+@NotNullByDefault
+public class Identity {
+
+	private final LocalAuthor localAuthor;
+	@Nullable
+	private final PublicKey handshakePublicKey;
+	@Nullable
+	private final PrivateKey handshakePrivateKey;
+	private final long created;
+
+	public Identity(LocalAuthor localAuthor,
+			@Nullable PublicKey handshakePublicKey,
+			@Nullable PrivateKey handshakePrivateKey, long created) {
+		if (handshakePublicKey != null) {
+			if (handshakePrivateKey == null)
+				throw new IllegalArgumentException();
+			if (!handshakePublicKey.getKeyType().equals(KEY_TYPE_AGREEMENT))
+				throw new IllegalArgumentException();
+		}
+		if (handshakePrivateKey != null) {
+			if (handshakePublicKey == null)
+				throw new IllegalArgumentException();
+			if (!handshakePrivateKey.getKeyType().equals(KEY_TYPE_AGREEMENT))
+				throw new IllegalArgumentException();
+		}
+		this.localAuthor = localAuthor;
+		this.handshakePublicKey = handshakePublicKey;
+		this.handshakePrivateKey = handshakePrivateKey;
+		this.created = created;
+	}
+
+	/**
+	 * Returns the ID of the user's pseudonym.
+	 */
+	public AuthorId getId() {
+		return localAuthor.getId();
+	}
+
+	/**
+	 * Returns the user's pseudonym.
+	 */
+	public LocalAuthor getLocalAuthor() {
+		return localAuthor;
+	}
+
+	/**
+	 * Returns true if the identity has a handshake key pair.
+	 */
+	public boolean hasHandshakeKeyPair() {
+		return handshakePublicKey != null && handshakePrivateKey != null;
+	}
+
+	/**
+	 * Returns the public key used for handshaking, or null if no key exists.
+	 */
+	@Nullable
+	public PublicKey getHandshakePublicKey() {
+		return handshakePublicKey;
+	}
+
+	/**
+	 * Returns the private key used for handshaking, or null if no key exists.
+	 */
+	@Nullable
+	public PrivateKey getHandshakePrivateKey() {
+		return handshakePrivateKey;
+	}
+
+	/**
+	 * Returns the time the identity was created, in milliseconds since the
+	 * Unix epoch.
+	 */
+	public long getTimeCreated() {
+		return created;
+	}
+}

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

@@ -1,30 +1,30 @@
 package org.briarproject.bramble.api.identity;
 
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.crypto.KeyPair;
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 @NotNullByDefault
 public interface IdentityManager {
 
 	/**
-	 * Creates a local identity with the given name.
+	 * Creates an identity with the given name. The identity includes a
+	 * handshake key pair.
 	 */
 	@CryptoExecutor
-	LocalAuthor createLocalAuthor(String name);
+	Identity createIdentity(String name);
 
 	/**
-	 * Registers the given local identity with the manager. The identity is
-	 * not stored until {@link #storeLocalAuthor()} is called.
+	 * Registers the given identity with the manager. This method should be
+	 * called before {@link LifecycleManager#startServices(SecretKey)}. The
+	 * identity is stored when {@link LifecycleManager#startServices(SecretKey)}
+	 * is called. The identity must include a handshake key pair.
 	 */
-	void registerLocalAuthor(LocalAuthor a);
-
-	/**
-	 * Stores the local identity registered with
-	 * {@link #registerLocalAuthor(LocalAuthor)}, if any.
-	 */
-	void storeLocalAuthor() throws DbException;
+	void registerIdentity(Identity i);
 
 	/**
 	 * Returns the cached local identity or loads it from the database.
@@ -33,7 +33,15 @@ public interface IdentityManager {
 
 	/**
 	 * Returns the cached local identity or loads it from the database.
+	 * <p/>
+	 * Read-only.
 	 */
 	LocalAuthor getLocalAuthor(Transaction txn) throws DbException;
 
+	/**
+	 * Returns the cached handshake keys or loads them from the database.
+	 * <p/>
+	 * Read-only.
+	 */
+	KeyPair getHandshakeKeys(Transaction txn) throws DbException;
 }

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

@@ -1,9 +1,13 @@
 package org.briarproject.bramble.api.identity;
 
+import org.briarproject.bramble.api.crypto.PrivateKey;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
+
 /**
  * A pseudonym for the local user.
  */
@@ -11,28 +15,20 @@ import javax.annotation.concurrent.Immutable;
 @NotNullByDefault
 public class LocalAuthor extends Author {
 
-	private final byte[] privateKey;
-	private final long created;
+	private final PrivateKey privateKey;
 
 	public LocalAuthor(AuthorId id, int formatVersion, String name,
-			byte[] publicKey, byte[] privateKey, long created) {
+			PublicKey publicKey, PrivateKey privateKey) {
 		super(id, formatVersion, name, publicKey);
+		if (!privateKey.getKeyType().equals(KEY_TYPE_SIGNATURE))
+			throw new IllegalArgumentException();
 		this.privateKey = privateKey;
-		this.created = created;
 	}
 
 	/**
 	 * Returns the private key used to generate the pseudonym's signatures.
 	 */
-	public byte[] getPrivateKey() {
+	public PrivateKey getPrivateKey() {
 		return privateKey;
 	}
-
-	/**
-	 * Returns the time the pseudonym was created, in milliseconds since the
-	 * Unix epoch.
-	 */
-	public long getTimeCreated() {
-		return created;
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/identity/event/IdentityAddedEvent.java

@@ -7,15 +7,15 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a local pseudonym is added.
+ * An event that is broadcast when an identity is added.
  */
 @Immutable
 @NotNullByDefault
-public class LocalAuthorAddedEvent extends Event {
+public class IdentityAddedEvent extends Event {
 
 	private final AuthorId authorId;
 
-	public LocalAuthorAddedEvent(AuthorId authorId) {
+	public IdentityAddedEvent(AuthorId authorId) {
 		this.authorId = authorId;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/identity/event/IdentityRemovedEvent.java

@@ -7,15 +7,15 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a local pseudonym is removed.
+ * An event that is broadcast when an identity is removed.
  */
 @Immutable
 @NotNullByDefault
-public class LocalAuthorRemovedEvent extends Event {
+public class IdentityRemovedEvent extends Event {
 
 	private final AuthorId authorId;
 
-	public LocalAuthorRemovedEvent(AuthorId authorId) {
+	public IdentityRemovedEvent(AuthorId authorId) {
 		this.authorId = authorId;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/io/BlockSink.java

@@ -1,20 +0,0 @@
-package org.briarproject.bramble.api.io;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.sync.tree.TreeHash;
-
-import java.util.List;
-
-public interface BlockSink {
-
-	/**
-	 * Stores a block of the message with the given temporary ID.
-	 */
-	void putBlock(HashingId h, int blockNumber, byte[] data) throws DbException;
-
-	/**
-	 * Sets the hash tree path of a previously stored block.
-	 */
-	void setPath(HashingId h, int blockNumber, List<TreeHash> path)
-			throws DbException;
-}

bramble-api/src/main/java/org/briarproject/bramble/api/io/HashingId.java

@@ -1,27 +0,0 @@
-package org.briarproject.bramble.api.io;
-
-import org.briarproject.bramble.api.UniqueId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.Message;
-import org.briarproject.bramble.api.sync.MessageId;
-
-import javax.annotation.concurrent.ThreadSafe;
-
-/**
- * Type-safe wrapper for a byte array that uniquely identifies a
- * {@link Message} while it's being hashed and the {@link MessageId} is not
- * yet known.
- */
-@ThreadSafe
-@NotNullByDefault
-public class HashingId extends UniqueId {
-
-	public HashingId(byte[] id) {
-		super(id);
-	}
-
-	@Override
-	public boolean equals(Object o) {
-		return o instanceof HashingId && super.equals(o);
-	}
-}

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

@@ -40,8 +40,8 @@ public interface KeyAgreementConstants {
 			"org.briarproject.bramble.keyagreement/SHARED_SECRET";
 
 	/**
-	 * Label for deriving the master secret.
+	 * Label for deriving the master key.
 	 */
-	String MASTER_SECRET_LABEL =
+	String MASTER_KEY_LABEL =
 			"org.briarproject.bramble.keyagreement/MASTER_SECRET";
 }

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

@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.data.BdfList;
 import java.io.IOException;
 
 /**
- * An class for managing a particular key agreement listener.
+ * Accepts key agreement connections over a given transport.
  */
 public abstract class KeyAgreementListener {
 

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

@@ -1,20 +0,0 @@
-package org.briarproject.bramble.api.keyagreement;
-
-import java.io.IOException;
-
-/**
- * Thrown when a QR code that has been scanned uses a protocol version that is
- * not supported.
- */
-public class UnsupportedVersionException extends IOException {
-
-	private final boolean tooOld;
-
-	public UnsupportedVersionException(boolean tooOld) {
-		this.tooOld = tooOld;
-	}
-
-	public boolean isTooOld() {
-		return tooOld;
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java

@@ -2,16 +2,16 @@ package org.briarproject.bramble.api.lifecycle;
 
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.Client;
 
 import java.util.concurrent.ExecutorService;
 
 /**
- * Manages the lifecycle of the app, starting {@link Client Clients}, starting
- * and stopping {@link Service Services}, shutting down
- * {@link ExecutorService ExecutorServices}, and opening and closing the
- * {@link DatabaseComponent}.
+ * Manages the lifecycle of the app: opening and closing the
+ * {@link DatabaseComponent} starting and stopping {@link Service Services},
+ * and shutting down {@link ExecutorService ExecutorServices}.
  */
 @NotNullByDefault
 public interface LifecycleManager {
@@ -42,18 +42,19 @@ public interface LifecycleManager {
 		}
 	}
 
+	/**
+	 * Registers a hook to be called after the database is opened and before
+	 * {@link Service services} are started. This method should be called
+	 * before {@link #startServices(SecretKey)}.
+	 */
+	void registerOpenDatabaseHook(OpenDatabaseHook hook);
+
 	/**
 	 * Registers a {@link Service} to be started and stopped. This method
 	 * should be called before {@link #startServices(SecretKey)}.
 	 */
 	void registerService(Service s);
 
-	/**
-	 * Registers a {@link Client} to be started. This method should be called
-	 * before {@link #startServices(SecretKey)}.
-	 */
-	void registerClient(Client c);
-
 	/**
 	 * Registers an {@link ExecutorService} to be shut down. This method
 	 * should be called before {@link #startServices(SecretKey)}.
@@ -62,7 +63,7 @@ public interface LifecycleManager {
 
 	/**
 	 * Opens the {@link DatabaseComponent} using the given key and starts any
-	 * registered {@link Client Clients} and {@link Service Services}.
+	 * registered {@link Service Services}.
 	 */
 	StartResult startServices(SecretKey dbKey);
 
@@ -80,8 +81,7 @@ public interface LifecycleManager {
 
 	/**
 	 * Waits for the {@link DatabaseComponent} to be opened and all registered
-	 * {@link Client Clients} and {@link Service Services} to start before
-	 * returning.
+	 * {@link Service Services} to start before returning.
 	 */
 	void waitForStartup() throws InterruptedException;
 
@@ -97,4 +97,13 @@ public interface LifecycleManager {
 	 */
 	LifecycleState getLifecycleState();
 
+	interface OpenDatabaseHook {
+		/**
+		 * Called when the database is being opened, before
+		 * {@link #waitForDatabase()} returns.
+		 *
+		 * @param txn A read-write transaction
+		 */
+		void onDatabaseOpened(Transaction txn) throws DbException;
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/nullsafety/NullSafety.java

@@ -6,10 +6,27 @@ import javax.annotation.Nullable;
 public class NullSafety {
 
 	/**
-	 * Stand-in for `Objects.requireNonNull()`.
+	 * Stand-in for {@code Objects.requireNonNull()}.
 	 */
 	public static <T> T requireNonNull(@Nullable T t) {
 		if (t == null) throw new NullPointerException();
 		return t;
 	}
+
+	/**
+	 * Checks that exactly one of the arguments is null.
+	 *
+	 * @throws AssertionError If both or neither of the arguments are null
+	 */
+	public static void requireExactlyOneNull(@Nullable Object a,
+			@Nullable Object b) {
+		if ((a == null) == (b == null)) throw new AssertionError();
+	}
+
+	/**
+	 * Checks that the argument is null.
+	 */
+	public static void requireNull(@Nullable Object o) {
+		if (o != null) throw new AssertionError();
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/ConnectionHandler.java

@@ -0,0 +1,28 @@
+package org.briarproject.bramble.api.plugin;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
+
+/**
+ * An interface for handling connections created by transport plugins.
+ */
+@NotNullByDefault
+public interface ConnectionHandler {
+
+	/**
+	 * Handles a connection created by a {@link DuplexPlugin}.
+	 */
+	void handleConnection(DuplexTransportConnection c);
+
+	/**
+	 * Handles a reader created by a {@link SimplexPlugin}.
+	 */
+	void handleReader(TransportConnectionReader r);
+
+	/**
+	 * Handles a writer created by a {@link SimplexPlugin}.
+	 */
+	void handleWriter(TransportConnectionWriter w);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/ConnectionManager.java

@@ -1,17 +1,46 @@
 package org.briarproject.bramble.api.plugin;
 
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+@NotNullByDefault
 public interface ConnectionManager {
 
+	/**
+	 * Manages an incoming connection from a contact over a simplex transport.
+	 */
 	void manageIncomingConnection(TransportId t, TransportConnectionReader r);
 
+	/**
+	 * Manages an incoming connection from a contact over a duplex transport.
+	 */
 	void manageIncomingConnection(TransportId t, DuplexTransportConnection d);
 
+	/**
+	 * Manages an incoming handshake connection from a pending contact over a
+	 * duplex transport.
+	 */
+	void manageIncomingConnection(PendingContactId p, TransportId t,
+			DuplexTransportConnection d);
+
+	/**
+	 * Manages an outgoing connection to a contact over a simplex transport.
+	 */
 	void manageOutgoingConnection(ContactId c, TransportId t,
 			TransportConnectionWriter w);
 
+	/**
+	 * Manages an outgoing connection to a contact over a duplex transport.
+	 */
 	void manageOutgoingConnection(ContactId c, TransportId t,
 			DuplexTransportConnection d);
+
+	/**
+	 * Manages an outgoing handshake connection to a pending contact over a
+	 * duplex transport.
+	 */
+	void manageOutgoingConnection(PendingContactId p, TransportId t,
+			DuplexTransportConnection d);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/ConnectionRegistry.java

@@ -1,7 +1,14 @@
 package org.briarproject.bramble.api.plugin;
 
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
+import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
+import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionClosedEvent;
+import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionOpenedEvent;
 
 import java.util.Collection;
 
@@ -11,13 +18,50 @@ import java.util.Collection;
 @NotNullByDefault
 public interface ConnectionRegistry {
 
+	/**
+	 * Registers a connection with the given contact over the given transport.
+	 * Broadcasts {@link ConnectionOpenedEvent}. Also broadcasts
+	 * {@link ContactConnectedEvent} if this is the only connection with the
+	 * contact.
+	 */
 	void registerConnection(ContactId c, TransportId t, boolean incoming);
 
+	/**
+	 * Unregisters a connection with the given contact over the given transport.
+	 * Broadcasts {@link ConnectionClosedEvent}. Also broadcasts
+	 * {@link ContactDisconnectedEvent} if this is the only connection with
+	 * the contact.
+	 */
 	void unregisterConnection(ContactId c, TransportId t, boolean incoming);
 
+	/**
+	 * Returns any contacts that are connected via the given transport.
+	 */
 	Collection<ContactId> getConnectedContacts(TransportId t);
 
+	/**
+	 * Returns true if the given contact is connected via the given transport.
+	 */
 	boolean isConnected(ContactId c, TransportId t);
 
+	/**
+	 * Returns true if the given contact is connected via any transport.
+	 */
 	boolean isConnected(ContactId c);
+
+	/**
+	 * Registers a connection with the given pending contact. Broadcasts
+	 * {@link RendezvousConnectionOpenedEvent} if this is the only connection
+	 * with the pending contact.
+	 *
+	 * @return True if this is the only connection with the pending contact,
+	 * false if it is redundant and should be closed
+	 */
+	boolean registerConnection(PendingContactId p);
+
+	/**
+	 * Unregisters a connection with the given pending contact. Broadcasts
+	 * {@link RendezvousConnectionClosedEvent}.
+	 */
+	void unregisterConnection(PendingContactId p, boolean success);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/Plugin.java

@@ -1,10 +1,10 @@
 package org.briarproject.bramble.api.plugin;
 
-import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.properties.TransportProperties;
 
-import java.util.Map;
+import java.util.Collection;
 
 @NotNullByDefault
 public interface Plugin {
@@ -51,8 +51,9 @@ public interface Plugin {
 	int getPollingInterval();
 
 	/**
-	 * Attempts to establish connections to the given contacts, passing any
-	 * created connections to the callback.
+	 * Attempts to create connections using the given transport properties,
+	 * passing any created connections to the corresponding handlers.
 	 */
-	void poll(Map<ContactId, TransportProperties> contacts);
+	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
+			properties);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/PluginCallback.java

@@ -9,7 +9,7 @@ import org.briarproject.bramble.api.settings.Settings;
  * the application.
  */
 @NotNullByDefault
-public interface PluginCallback {
+public interface PluginCallback extends ConnectionHandler {
 
 	/**
 	 * Returns the plugin's settings

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/PluginManager.java

@@ -36,4 +36,9 @@ public interface PluginManager {
 	 * Returns any duplex plugins that support key agreement.
 	 */
 	Collection<DuplexPlugin> getKeyAgreementPlugins();
+
+	/**
+	 * Returns any duplex plugins that support rendezvous.
+	 */
+	Collection<DuplexPlugin> getRendezvousPlugins();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TorConstants.java

@@ -16,6 +16,7 @@ public interface TorConstants {
 	String PREF_TOR_NETWORK = "network2";
 	String PREF_TOR_PORT = "port";
 	String PREF_TOR_MOBILE = "useMobileData";
+	String PREF_TOR_ONLY_WHEN_CHARGING = "onlyWhenCharging";
 
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;
 	int PREF_TOR_NETWORK_WITHOUT_BRIDGES = 1;

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/duplex/DuplexPlugin.java

@@ -3,8 +3,11 @@ package org.briarproject.bramble.api.plugin.duplex;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
+import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
 
 import javax.annotation.Nullable;
 
@@ -40,4 +43,19 @@ public interface DuplexPlugin extends Plugin {
 	@Nullable
 	DuplexTransportConnection createKeyAgreementConnection(
 			byte[] remoteCommitment, BdfList descriptor);
+
+	/**
+	 * Returns true if the plugin supports rendezvous connections.
+	 */
+	boolean supportsRendezvous();
+
+	/**
+	 * Creates and returns an endpoint that uses the given key material to
+	 * rendezvous with a pending contact, and the given connection handler to
+	 * handle incoming connections. Returns null if an endpoint cannot be
+	 * created.
+	 */
+	@Nullable
+	RendezvousEndpoint createRendezvousEndpoint(KeyMaterialSource k,
+			boolean alice, ConnectionHandler incoming);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/duplex/DuplexPluginCallback.java

@@ -1,17 +0,0 @@
-package org.briarproject.bramble.api.plugin.duplex;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
-
-/**
- * An interface through which a duplex plugin interacts with the rest of the
- * application.
- */
-@NotNullByDefault
-public interface DuplexPluginCallback extends PluginCallback {
-
-	void incomingConnectionCreated(DuplexTransportConnection d);
-
-	void outgoingConnectionCreated(ContactId c, DuplexTransportConnection d);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/duplex/DuplexPluginFactory.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.plugin.duplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.Nullable;
@@ -25,5 +26,5 @@ public interface DuplexPluginFactory {
 	 * Creates and returns a plugin, or null if no plugin can be created.
 	 */
 	@Nullable
-	DuplexPlugin createPlugin(DuplexPluginCallback callback);
+	DuplexPlugin createPlugin(PluginCallback callback);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/simplex/SimplexPluginCallback.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.api.plugin.simplex;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.plugin.TransportConnectionReader;
-import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
-
-/**
- * An interface through which a simplex plugin interacts with the rest of the
- * application.
- */
-@NotNullByDefault
-public interface SimplexPluginCallback extends PluginCallback {
-
-	void readerCreated(TransportConnectionReader r);
-
-	void writerCreated(ContactId c, TransportConnectionWriter w);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/simplex/SimplexPluginFactory.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.plugin.simplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.Nullable;
@@ -25,5 +26,5 @@ public interface SimplexPluginFactory {
 	 * Creates and returns a plugin, or null if no plugin can be created.
 	 */
 	@Nullable
-	SimplexPlugin createPlugin(SimplexPluginCallback callback);
+	SimplexPlugin createPlugin(PluginCallback callback);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordReader.java

@@ -1,10 +1,14 @@
 package org.briarproject.bramble.api.record;
 
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.Predicate;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.EOFException;
 import java.io.IOException;
 
+import javax.annotation.Nullable;
+
 @NotNullByDefault
 public interface RecordReader {
 
@@ -16,5 +20,20 @@ public interface RecordReader {
 	 */
 	Record readRecord() throws IOException;
 
+	/**
+	 * Reads and returns the next record matching the 'accept' predicate,
+	 * skipping any records that match the 'ignore' predicate. Returns null if
+	 * no record matching the 'accept' predicate is found before the end of the
+	 * stream.
+	 *
+	 * @throws EOFException If the end of the stream is reached without
+	 * reading a complete record
+	 * @throws FormatException If a record is read that does not match the
+	 * 'accept' or 'ignore' predicates
+	 */
+	@Nullable
+	Record readRecord(Predicate<Record> accept, Predicate<Record> ignore)
+			throws IOException;
+
 	void close() throws IOException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/KeyMaterialSource.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.rendezvous;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * A source of key material for use in making rendezvous connections.
+ */
+@NotNullByDefault
+public interface KeyMaterialSource {
+
+	/**
+	 * Returns the requested amount of key material.
+	 */
+	byte[] getKeyMaterial(int length);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/RendezvousEndpoint.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.rendezvous;
+
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.io.Closeable;
+import java.io.IOException;
+
+/**
+ * An interface for making and accepting rendezvous connections with a pending
+ * contact over a given transport.
+ */
+public interface RendezvousEndpoint extends Closeable {
+
+	/**
+	 * Returns a set of transport properties for connecting to the pending
+	 * contact.
+	 */
+	TransportProperties getRemoteTransportProperties();
+
+	/**
+	 * Closes the handler and releases any resources held by it, such as
+	 * network sockets.
+	 */
+	@Override
+	void close() throws IOException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/RendezvousPoller.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.api.rendezvous;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+
+/**
+ * Interface for the poller that makes rendezvous connections to pending
+ * contacts.
+ */
+public interface RendezvousPoller {
+
+	long getLastPollTime(PendingContactId p);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/event/RendezvousConnectionClosedEvent.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.rendezvous.event;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a rendezvous connection is closed.
+ */
+@Immutable
+@NotNullByDefault
+public class RendezvousConnectionClosedEvent extends Event {
+
+	private final PendingContactId pendingContactId;
+	private final boolean success;
+
+	public RendezvousConnectionClosedEvent(PendingContactId pendingContactId,
+			boolean success) {
+		this.pendingContactId = pendingContactId;
+		this.success = success;
+	}
+
+	public PendingContactId getPendingContactId() {
+		return pendingContactId;
+	}
+
+	public boolean isSuccess() {
+		return success;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/event/RendezvousConnectionOpenedEvent.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.rendezvous.event;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a rendezvous connection is opened.
+ */
+@Immutable
+@NotNullByDefault
+public class RendezvousConnectionOpenedEvent extends Event {
+
+	private final PendingContactId pendingContactId;
+
+	public RendezvousConnectionOpenedEvent(PendingContactId pendingContactId) {
+		this.pendingContactId = pendingContactId;
+	}
+
+	public PendingContactId getPendingContactId() {
+		return pendingContactId;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/rendezvous/event/RendezvousPollEvent.java

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.api.rendezvous.event;
+
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+
+import java.util.Collection;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a transport plugin is polled for connections
+ * to one or more pending contacts.
+ */
+@Immutable
+@NotNullByDefault
+public class RendezvousPollEvent extends Event {
+
+	private final TransportId transportId;
+	private final Collection<PendingContactId> pendingContacts;
+
+	public RendezvousPollEvent(TransportId transportId,
+			Collection<PendingContactId> pendingContacts) {
+		this.transportId = transportId;
+		this.pendingContacts = pendingContacts;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public Collection<PendingContactId> getPendingContacts() {
+		return pendingContacts;
+	}
+}