Remove local author from contacts.

.gitlab-ci.yml

@@ -1,11 +1,6 @@
 image: briar/ci-image-android:latest
 
-stages:
-- test
-- check_reproducibility
-
 test:
-  stage: test
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
@@ -26,7 +21,6 @@ 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

@@ -39,6 +39,31 @@
     <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

@@ -0,0 +1,20 @@
+<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

@@ -1,20 +1,30 @@
 <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="$PROJECT_DIR$/briar-android" />
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    <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="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 tests in briar-headless" run_configuration_type="AndroidJUnit" />
+      <option name="RunConfigurationTask" enabled="true" run_configuration_name="All in briar-headless" run_configuration_type="AndroidJUnit" />
     </method>
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_headless.xml

@@ -1,15 +0,0 @@
-<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 10107
-		versionName "1.1.7"
+		versionCode 10106
+		versionName "1.1.6"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -33,7 +33,7 @@ dependencies {
 	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:2.22.1'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 

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

@@ -2,13 +2,10 @@ 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

@@ -3,8 +3,6 @@ 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;
@@ -13,15 +11,12 @@ import dagger.Module;
 		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
-		CircumventionModule.class,
-		ReportingModule.class,
-		SocksModule.class
+		CircumventionModule.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

@@ -9,6 +9,7 @@ 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;
@@ -19,9 +20,6 @@ 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 {
@@ -43,16 +41,6 @@ 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
@@ -86,17 +74,9 @@ 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());
-			}
 		}
 	}
 
@@ -114,7 +94,7 @@ class AndroidAccountManager extends AccountManagerImpl
 		}
 		// Delete files, except lib and shared_prefs directories
 		Set<File> files = new HashSet<>();
-		File dataDir = getDataDir();
+		File dataDir = new File(appContext.getApplicationInfo().dataDir);
 		@Nullable
 		File[] fileArray = dataDir.listFiles();
 		if (fileArray == null) {
@@ -141,17 +121,13 @@ class AndroidAccountManager extends AccountManagerImpl
 			}
 		}
 		for (File file : files) {
-			deleteFileOrDir(file);
+			IoUtils.deleteFileOrDir(file);
 		}
 		// Recreate the cache dir as some OpenGL drivers expect it to exist
 		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/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;
@@ -51,7 +51,6 @@ 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
@@ -59,7 +58,7 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	private static final Logger LOG =
-			getLogger(AndroidBluetoothPlugin.class.getName());
+			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
 
 	private static final int MAX_DISCOVERY_MS = 10_000;
 
@@ -76,7 +75,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
 			Executor ioExecutor, AndroidExecutor androidExecutor,
 			Context appContext, SecureRandom secureRandom, Clock clock,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
+			Backoff backoff, DuplexPluginCallback 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(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback 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.PluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -32,18 +32,17 @@ 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);
@@ -61,7 +60,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	private volatile SocketFactory socketFactory;
 
 	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
-			Backoff backoff, PluginCallback callback, int maxLatency,
+			Backoff backoff, DuplexPluginCallback 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(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback 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.PluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
@@ -41,12 +41,11 @@ class AndroidTorPlugin extends TorPlugin {
 			Clock clock, ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager, Backoff backoff,
-			TorRendezvousCrypto torRendezvousCrypto,
-			PluginCallback callback, String architecture, int maxLatency,
+			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
 				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, torRendezvousCrypto, callback, architecture, maxLatency, maxIdleTime,
+				backoff, callback, architecture, maxLatency, maxIdleTime,
 				appContext.getDir("tor", MODE_PRIVATE));
 		this.appContext = appContext;
 		PowerManager pm = (PowerManager)

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(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 
 		// Check that we have a Tor binary for this architecture
 		String architecture = null;
@@ -106,12 +106,10 @@ 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, torRendezvousCrypto, callback, architecture,
-				MAX_LATENCY, MAX_IDLE_TIME);
+				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -128,7 +128,7 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 			will(returnValue(editor));
 			oneOf(editor).commit();
 			will(returnValue(true));
-			allowing(app).getApplicationInfo();
+			oneOf(app).getApplicationInfo();
 			will(returnValue(applicationInfo));
 			oneOf(app).getFilesDir();
 			will(returnValue(filesDir));

bramble-android/witness.gradle

@@ -1,45 +1,45 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        '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.android.tools.analytics-library:protos:26.3.2:protos-26.3.2.jar:50238fb4298b297217b184b9cd93c14f83536fcee829eb0ca850bdb5b53251f0',
+        'com.android.tools.analytics-library:shared:26.3.2:shared-26.3.2.jar:ddd80dcf21905018b7c0583ba72b7282f446084d4952422609a09fbf8237ef71',
+        'com.android.tools.analytics-library:tracker:26.3.2:tracker-26.3.2.jar:28c575d2d1af003e96d7b375a668ee10b2673a2dd0f6438750aa8c3b42e7d0ad',
+        'com.android.tools.build:apksig:3.3.2:apksig-3.3.2.jar:84c4aaa20127c6c1fe6bdd334b3f5df71f54ad080be9029c8a10f43b6a908acd',
+        'com.android.tools.build:apkzlib:3.3.2:apkzlib-3.3.2.jar:d34e523278e5dff565eba3ef3c089d515b2b5cc7b47dc77e2f3465e5e47176ac',
+        'com.android.tools.build:builder-model:3.3.2:builder-model-3.3.2.jar:055e3db0ecee9e06b9f024034999a29cd92cb1885207b37542126bd8bcc57f46',
+        'com.android.tools.build:builder-test-api:3.3.2:builder-test-api-3.3.2.jar:0b2e4cd7615bbcad14a3c91fe45ae26693508d06e40ba06c5968b8bc24416618',
+        'com.android.tools.build:builder:3.3.2:builder-3.3.2.jar:65649704da7aef0487235fd326f0f2e99ed5cf958e80f204496e6e08a42bd9f5',
+        'com.android.tools.build:gradle-api:3.3.2:gradle-api-3.3.2.jar:3cbd47e41bb70330dd72ec2c9fe51e6173554b484a03829b5a2de9e00841e040',
+        'com.android.tools.build:manifest-merger:26.3.2:manifest-merger-26.3.2.jar:05c4a6d8b02fb9f08744876477d0a68547c03a8a9069b1f086684fa04af97c33',
+        'com.android.tools.ddms:ddmlib:26.3.2:ddmlib-26.3.2.jar:d248da8a563d6e46d2c7ebbf371a4877e00510f4ca763c0bb272d5a281bf8b85',
+        'com.android.tools.external.com-intellij:intellij-core:26.3.2:intellij-core-26.3.2.jar:6c5ecc968230e9f4dcd0fef28885379feace1f0cd8130de6f61d649c86139bf3',
+        'com.android.tools.external.com-intellij:kotlin-compiler:26.3.2:kotlin-compiler-26.3.2.jar:1007d9b07ccb49cd8eaf30fda10ed4681d4714f2f9ab2ecda39b4e539cc51bbe',
+        'com.android.tools.external.org-jetbrains:uast:26.3.2:uast-26.3.2.jar:5d1833e562ea4f38a89708dfde695f0a162cbd39d003d3dde818c3fdc2b05317',
+        'com.android.tools.layoutlib:layoutlib-api:26.3.2:layoutlib-api-26.3.2.jar:d7e61e874ab95f5c350dd38b6a95b5c9dbe0083a02001884264cdb390cb255b8',
+        'com.android.tools.lint:lint-api:26.3.2:lint-api-26.3.2.jar:5867dfd7fb4a4e161a816a5d29d045f9b542d34594c00a1efec46fb4cd0e1033',
+        'com.android.tools.lint:lint-checks:26.3.2:lint-checks-26.3.2.jar:4b163b9c93790d2771e92ba8de58a0d9e0671ffcf2ccef3cf496efd442e27517',
+        'com.android.tools.lint:lint-gradle-api:26.3.2:lint-gradle-api-26.3.2.jar:54cb282e0c054f9bed3f51302ce08b003c8ab7961dfd5a4f6de26c23cc23062f',
+        'com.android.tools.lint:lint-gradle:26.3.2:lint-gradle-26.3.2.jar:bb139615f4ce97d42cc394b9389b49b76a6eb85be6785a5d272991543b519013',
+        'com.android.tools.lint:lint:26.3.2:lint-26.3.2.jar:ef7b369f8a56a92ccb0f4c1c357666b9339e4a711a9d84747d446441746cfe4e',
+        'com.android.tools:annotations:26.3.2:annotations-26.3.2.jar:5bcce8e98b6a2f5ccf13ebcefd8f734e0b35f8b19e456575665631442ce1f7a1',
+        'com.android.tools:common:26.3.2:common-26.3.2.jar:d9f8e7f0669e9a701568e3db6a87c89cf12d8fa6811c9991e969f950215ecfac',
+        'com.android.tools:dvlib:26.3.2:dvlib-26.3.2.jar:d84aad56161c7773579303d69714ded6897c64c6ddfd7d456e453231e4dfe811',
+        'com.android.tools:repository:26.3.2:repository-26.3.2.jar:da611eeb06e9ab8750d25b9e2901e10db8e5ec6304eb4c8b7103d39e0921ea40',
+        'com.android.tools:sdk-common:26.3.2:sdk-common-26.3.2.jar:82823a3bf25e64fac33a286490f0cf5ac50c2cdb3c540149b030896bb44bf96c',
+        'com.android.tools:sdklib:26.3.2:sdklib-26.3.2.jar:424d15492af67321900963238646d27495ab60de2a5b19e6a416963bc5d6932b',
         '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:2.22.1: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.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:2.1.3: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:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
         '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.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
         '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',
@@ -48,7 +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:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
+        'commons-codec:commons-codec:1.9:commons-codec-1.9.jar:ad19d2601c3abf0b946b5c3a4113e226a8c1e3305e395b90013b78dd94a723ce',
         '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',
@@ -60,9 +60,9 @@ 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:4.5.6: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.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.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',

bramble-api/build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.22.1"
+	implementation "com.google.dagger:dagger:2.19"
 	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;
 
 /**
@@ -15,6 +15,8 @@ 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;
@@ -36,13 +38,20 @@ public class Bytes implements Comparable<Bytes> {
 	}
 
 	@Override
-	public boolean equals(@Nullable Object o) {
+	public boolean equals(Object o) {
 		return o instanceof Bytes && Arrays.equals(bytes, ((Bytes) o).bytes);
 	}
 
 	@Override
 	public int compareTo(Bytes other) {
-		return compare(bytes, other.bytes);
+		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;
 	}
 
 	@Override
@@ -51,13 +60,11 @@ public class Bytes implements Comparable<Bytes> {
 				"(" + StringUtils.toHexString(getBytes()) + ")";
 	}
 
-	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;
+	public static class BytesComparator implements Comparator<Bytes> {
+
+		@Override
+		public int compare(Bytes a, Bytes b) {
+			return a.compareTo(b);
 		}
-		return a.length - b.length;
 	}
 }

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

@@ -1,11 +0,0 @@
-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

@@ -1,9 +0,0 @@
-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

@@ -1,18 +0,0 @@
-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

@@ -33,8 +33,7 @@ public abstract class BdfIncomingMessageHook implements IncomingMessageHook {
 	/**
 	 * Called once for each incoming message that passes validation.
 	 *
-	 * @param txn A read-write transaction
-	 * @return Whether or not this message should be shared
+	 * @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

@@ -1,8 +1,6 @@
 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;
@@ -25,10 +23,7 @@ public interface ClientHelper {
 			throws DbException, FormatException;
 
 	void addLocalMessage(Transaction txn, Message m, BdfDictionary metadata,
-			boolean shared, boolean temporary)
-			throws DbException, FormatException;
-
-	Message createMessage(GroupId g, long timestamp, byte[] body);
+			boolean shared) throws DbException, FormatException;
 
 	Message createMessage(GroupId g, long timestamp, BdfList body)
 			throws FormatException;
@@ -101,18 +96,14 @@ public interface ClientHelper {
 
 	BdfList toList(Author a);
 
-	byte[] sign(String label, BdfList toSign, PrivateKey privateKey)
+	byte[] sign(String label, BdfList toSign, byte[] privateKey)
 			throws FormatException, GeneralSecurityException;
 
 	void verifySignature(byte[] signature, String label, BdfList signed,
-			PublicKey publicKey)
-			throws FormatException, GeneralSecurityException;
+			byte[] 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/client/ContactGroupFactory.java

@@ -18,11 +18,10 @@ public interface ContactGroupFactory {
 	 * Creates a group for the given client to share with the given contact.
 	 */
 	Group createContactGroup(ClientId clientId, int majorVersion,
-			Contact contact);
+			Contact contact, AuthorId local);
 
 	/**
-	 * Creates a group for the given client to share between the given authors
-	 * identified by their AuthorIds.
+	 * Creates a group for the given client to share between the given authors.
 	 */
 	Group createContactGroup(ClientId clientId, int majorVersion,
 			AuthorId authorId1, AuthorId authorId2);

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

@@ -1,14 +1,13 @@
 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;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 @Immutable
@@ -17,24 +16,25 @@ public class Contact {
 
 	private final ContactId id;
 	private final Author author;
-	private final AuthorId localAuthorId;
 	@Nullable
 	private final String alias;
 	@Nullable
-	private final PublicKey handshakePublicKey;
+	private final byte[] handshakePublicKey;
 	private final boolean verified;
 
-	public Contact(ContactId id, Author author, AuthorId localAuthorId,
-			@Nullable String alias, @Nullable PublicKey handshakePublicKey,
-			boolean verified) {
+	public Contact(ContactId id, Author author, @Nullable String alias,
+			@Nullable byte[] handshakePublicKey, boolean verified) {
 		if (alias != null) {
 			int aliasLength = toUtf8(alias).length;
 			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
 				throw new IllegalArgumentException();
 		}
+		if (handshakePublicKey != null && (handshakePublicKey.length == 0 ||
+				handshakePublicKey.length > MAX_PUBLIC_KEY_LENGTH)) {
+			throw new IllegalArgumentException();
+		}
 		this.id = id;
 		this.author = author;
-		this.localAuthorId = localAuthorId;
 		this.alias = alias;
 		this.handshakePublicKey = handshakePublicKey;
 		this.verified = verified;
@@ -48,17 +48,13 @@ public class Contact {
 		return author;
 	}
 
-	public AuthorId getLocalAuthorId() {
-		return localAuthorId;
-	}
-
 	@Nullable
 	public String getAlias() {
 		return alias;
 	}
 
 	@Nullable
-	public PublicKey getHandshakePublicKey() {
+	public byte[] getHandshakePublicKey() {
 		return handshakePublicKey;
 	}
 

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

@@ -1,37 +0,0 @@
-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

@@ -1,6 +1,16 @@
-package org.briarproject.bramble.contact;
+package org.briarproject.bramble.api.contact;
 
-interface ContactExchangeConstants {
+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.
@@ -29,7 +39,9 @@ interface ContactExchangeConstants {
 	String BOB_NONCE_LABEL = "org.briarproject.bramble.contact/BOB_NONCE";
 
 	/**
-	 * Label for signing key binding nonces.
+	 * Exchanges contact information with a remote peer.
 	 */
-	String SIGNING_LABEL = "org.briarproject.briar.contact/EXCHANGE";
+	void startExchange(LocalAuthor localAuthor, SecretKey masterKey,
+			DuplexTransportConnection conn, TransportId transportId,
+			boolean alice);
 }

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

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

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

@@ -1,11 +1,7 @@
 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;
@@ -13,7 +9,6 @@ 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;
@@ -29,115 +24,60 @@ public interface ContactManager {
 	void registerContactHook(ContactHook hook);
 
 	/**
-	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores rotation mode transport keys for each transport, and
-	 * returns an ID for the contact.
+	 * Stores a contact with the given pseudonym, derives and stores 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
+	 * @param alice true if the local party is Alice
 	 */
-	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			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) throws DbException;
-
-	/**
-	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores 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
-	 */
-	ContactId addContact(Author remote, AuthorId local, SecretKey rootKey,
+	ContactId addContact(Transaction txn, Author a, 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.
+	 * Stores a contact with the given pseudonym and returns an ID for the
+	 * contact.
 	 */
-	String getHandshakeLink() throws DbException;
+	ContactId addContact(Transaction txn, Author a, boolean verified)
+			throws DbException;
 
 	/**
-	 * Creates a {@link PendingContact} from the given handshake link and
-	 * alias, adds it to the database and returns it.
+	 * Stores a contact with the given pseudonym, derives and stores transport
+	 * keys for each transport, and returns an ID for the contact.
 	 *
-	 * @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
+	 * @param alice true if the local party is Alice
 	 */
-	PendingContact addPendingContact(String link, String alias)
-			throws DbException, FormatException, GeneralSecurityException;
+	ContactId addContact(Author a, SecretKey rootKey, long timestamp,
+			boolean alice, boolean verified, boolean active) throws DbException;
 
 	/**
-	 * Returns the pending contact with the given ID.
+	 * Returns the static link that needs to be sent to the contact to be added.
 	 */
-	PendingContact getPendingContact(Transaction txn, PendingContactId p)
-			throws DbException;
+	String getRemoteContactLink();
 
 	/**
-	 * Returns a list of {@link PendingContact PendingContacts} and their
-	 * {@link PendingContactState states}.
+	 * Returns true if the given link is syntactically valid.
 	 */
-	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
-			throws DbException;
+	boolean isValidRemoteContactLink(String link);
 
 	/**
-	 * Removes a {@link PendingContact}.
+	 * Requests a new contact to be added via the given {@code link}.
+	 *
+	 * @param link The link received from the contact we want to add.
+	 * @param alias The alias the user has given this contact.
+	 * @return A PendingContact representing the contact to be added.
 	 */
-	void removePendingContact(PendingContactId p) throws DbException;
+	PendingContact addRemoteContactRequest(String link, String alias);
+
+	/**
+	 * Returns a list of {@link PendingContact}s.
+	 */
+	Collection<PendingContact> getPendingContacts();
+
+	/**
+	 * Removes a {@link PendingContact} that is in state
+	 * {@link PendingContactState FAILED}.
+	 */
+	void removePendingContact(PendingContact pendingContact);
 
 	/**
 	 * Returns the contact with the given ID.
@@ -147,28 +87,15 @@ public interface ContactManager {
 	/**
 	 * Returns the contact with the given ID.
 	 */
-	Contact getContact(Transaction txn, ContactId c) throws DbException;
+	Contact getContact(AuthorId a) throws DbException;
 
 	/**
-	 * Returns the contact with the given {@code remoteAuthorId}
-	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
-	 *
-	 * @throws NoSuchContactException If the contact is not in the database
+	 * Returns the contact with the given ID.
 	 */
-	Contact getContact(AuthorId remoteAuthorId, AuthorId localAuthorId)
-			throws DbException;
+	Contact getContact(Transaction txn, AuthorId a) throws DbException;
 
 	/**
-	 * Returns the contact with the given {@code remoteAuthorId}
-	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
-	 *
-	 * @throws NoSuchContactException If the contact is not in the database
-	 */
-	Contact getContact(Transaction txn, AuthorId remoteAuthorId,
-			AuthorId localAuthorId) throws DbException;
-
-	/**
-	 * Returns all contacts.
+	 * Returns all active contacts.
 	 */
 	Collection<Contact> getContacts() throws DbException;
 
@@ -183,30 +110,26 @@ public interface ContactManager {
 	void removeContact(Transaction txn, ContactId c) throws DbException;
 
 	/**
-	 * Sets an alias for the contact or unsets it if {@code alias} is null.
+	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */
 	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Sets an alias for the contact or unsets it if {@code alias} is null.
+	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */
 	void setContactAlias(ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
-	 * the local pseudonym with this {@code localAuthorId}.
+	 * Returns true if a contact with this pseudonym already exists.
 	 */
-	boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
-			AuthorId localAuthorId) throws DbException;
+	boolean contactExists(Transaction txn, AuthorId a) throws DbException;
 
 	/**
-	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
-	 * the local pseudonym with this {@code localAuthorId}.
+	 * Returns true if a contact with this pseudonym already exists.
 	 */
-	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
-			throws DbException;
+	boolean contactExists(AuthorId a) throws DbException;
 
 	/**
 	 * Returns the {@link AuthorInfo} for the given author.
@@ -220,20 +143,8 @@ 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

@@ -1,34 +0,0 @@
-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

@@ -1,45 +0,0 @@
-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

@@ -1,6 +1,5 @@
 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;
@@ -10,15 +9,17 @@ import javax.annotation.concurrent.Immutable;
 public class PendingContact {
 
 	private final PendingContactId id;
-	private final PublicKey publicKey;
+	private final byte[] publicKey;
 	private final String alias;
+	private final PendingContactState state;
 	private final long timestamp;
 
-	public PendingContact(PendingContactId id, PublicKey publicKey,
-			String alias, long timestamp) {
+	public PendingContact(PendingContactId id, byte[] publicKey,
+			String alias, PendingContactState state, long timestamp) {
 		this.id = id;
 		this.publicKey = publicKey;
 		this.alias = alias;
+		this.state = state;
 		this.timestamp = timestamp;
 	}
 
@@ -26,7 +27,7 @@ public class PendingContact {
 		return id;
 	}
 
-	public PublicKey getPublicKey() {
+	public byte[] getPublicKey() {
 		return publicKey;
 	}
 
@@ -34,6 +35,10 @@ public class PendingContact {
 		return alias;
 	}
 
+	public PendingContactState getState() {
+		return state;
+	}
+
 	public long getTimestamp() {
 		return timestamp;
 	}

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

@@ -3,7 +3,6 @@ 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;
 
 /**
@@ -18,8 +17,9 @@ public class PendingContactId extends UniqueId {
 		super(id);
 	}
 
+
 	@Override
-	public boolean equals(@Nullable Object o) {
+	public boolean equals(Object o) {
 		return o instanceof PendingContactId && super.equals(o);
 	}
 }

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

@@ -1,10 +1,30 @@
 package org.briarproject.bramble.api.contact;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
 public enum PendingContactState {
 
-	WAITING_FOR_CONNECTION,
-	OFFLINE,
-	CONNECTING,
-	ADDING_CONTACT,
-	FAILED
+	WAITING_FOR_CONNECTION(0),
+	CONNECTED(1),
+	ADDING_CONTACT(2),
+	FAILED(3);
+
+	private final int value;
+
+	PendingContactState(int value) {
+		this.value = value;
+	}
+
+	public int getValue() {
+		return value;
+	}
+
+	public static PendingContactState fromValue(int value) {
+		for (PendingContactState s : values()) if (s.value == value) return s;
+		throw new IllegalArgumentException();
+	}
 }

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

@@ -1,9 +1,9 @@
-package org.briarproject.bramble.contact;
+package org.briarproject.bramble.api.contact;
 
 /**
  * Record types for the contact exchange protocol.
  */
-interface ContactExchangeRecordTypes {
+public interface RecordTypes {
 
 	byte CONTACT_INFO = 0;
 }

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

@@ -14,18 +14,12 @@ import javax.annotation.concurrent.Immutable;
 public class ContactAddedEvent extends Event {
 
 	private final ContactId contactId;
-	private final boolean verified;
 
-	public ContactAddedEvent(ContactId contactId, boolean verified) {
+	public ContactAddedEvent(ContactId contactId) {
 		this.contactId = contactId;
-		this.verified = verified;
 	}
 
 	public ContactId getContactId() {
 		return contactId;
 	}
-
-	public boolean isVerified() {
-		return verified;
-	}
 }

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

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public class ContactExchangeFailedEvent extends Event {
+
+	@Nullable
+	private final Author duplicateRemoteAuthor;
+
+	public ContactExchangeFailedEvent(@Nullable Author duplicateRemoteAuthor) {
+		this.duplicateRemoteAuthor = duplicateRemoteAuthor;
+	}
+
+	public ContactExchangeFailedEvent() {
+		this(null);
+	}
+
+	@Nullable
+	public Author getDuplicateRemoteAuthor() {
+		return duplicateRemoteAuthor;
+	}
+
+	public boolean wasDuplicateContact() {
+		return duplicateRemoteAuthor != null;
+	}
+
+}

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

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class ContactExchangeSucceededEvent extends Event {
+
+	private final Author remoteAuthor;
+
+	public ContactExchangeSucceededEvent(Author remoteAuthor) {
+		this.remoteAuthor = remoteAuthor;
+	}
+
+	public Author getRemoteAuthor() {
+		return remoteAuthor;
+	}
+
+}

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

@@ -1,25 +0,0 @@
-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

@@ -1,26 +0,0 @@
-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/crypto/AgreementPrivateKey.java

@@ -1,30 +0,0 @@
-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

@@ -1,35 +0,0 @@
-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

@@ -27,78 +27,54 @@ 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 shared secret from two key pairs.
+	 * Derives a common shared secret from two public keys and one of the
+	 * corresponding private keys.
 	 *
-	 * @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
-	 * @param inputs Additional inputs that will be included in the derivation
-	 * of the shared secret
-	 * @return The shared secret
+	 * @param theirPublicKey the public key of the remote party
+	 * @param ourKeyPair the key pair of the local party
+	 * @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, PrivateKey privateKey)
+	byte[] sign(String label, byte[] toSign, byte[] 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,
-			PublicKey publicKey) throws GeneralSecurityException;
+			byte[] 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
 	 */
@@ -109,7 +85,7 @@ 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
 	 */
@@ -119,10 +95,10 @@ 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

@@ -7,21 +7,11 @@ 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/KeyPair.java

@@ -15,8 +15,6 @@ 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

@@ -8,11 +8,6 @@ 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

@@ -8,11 +8,6 @@ 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

@@ -1,30 +0,0 @@
-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

@@ -1,35 +0,0 @@
-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

@@ -1,10 +1,9 @@
 package org.briarproject.bramble.api.crypto;
 
 import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
-import java.security.GeneralSecurityException;
-
 /**
  * Crypto operations for the transport security protocol - see
  * https://code.briarproject.org/briar/briar-spec/blob/master/protocols/BTP.md
@@ -12,52 +11,35 @@ import java.security.GeneralSecurityException;
 public interface TransportCrypto {
 
 	/**
-	 * Returns true if the local peer is Alice.
-	 */
-	boolean isAlice(PublicKey theirHandshakePublicKey,
-			KeyPair ourHandshakeKeyPair);
-
-	/**
-	 * Derives the static master key shared with a contact or pending contact.
-	 */
-	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.
+	 * Derives initial transport keys for the given transport in the given
+	 * time period from the given root key.
 	 *
-	 * @param pendingContact Whether the static master key is shared with a
-	 * pending contact or a contact
+	 * @param alice whether the keys are for use by Alice or Bob.
+	 * @param active whether the keys are usable for outgoing streams.
 	 */
-	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,
+	TransportKeys deriveTransportKeys(TransportId t, SecretKey rootKey,
 			long timePeriod, boolean alice, boolean active);
 
+	/**
+	 * Rotates the given transport keys to the given time period. If the keys
+	 * are for the given period or any later period they are not rotated.
+	 */
+	TransportKeys rotateTransportKeys(TransportKeys k, long timePeriod);
+
 	/**
 	 * 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
+	 * @param alice whether the keys are for use by Alice or Bob.
 	 */
-	TransportKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
+	HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
 			long timePeriod, boolean alice);
 
 	/**
-	 * Updates the given transport keys to the given time period. If the keys
+	 * Updates the given handshake 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);
+	HandshakeKeys updateHandshakeKeys(HandshakeKeys 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/ContactExistsException.java

@@ -1,27 +1,8 @@
 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

@@ -4,12 +4,10 @@ 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.Identity;
+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.settings.Settings;
@@ -24,12 +22,14 @@ 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.KeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeySet;
+import org.briarproject.bramble.api.transport.HandshakeKeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.TransportKeySet;
+import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -39,7 +39,7 @@ import javax.annotation.Nullable;
  * to other components.
  */
 @NotNullByDefault
-public interface DatabaseComponent extends TransactionManager {
+public interface DatabaseComponent {
 
 	/**
 	 * Opens the database and returns true if the database already existed.
@@ -58,11 +58,55 @@ public interface DatabaseComponent extends TransactionManager {
 	void close() throws DbException;
 
 	/**
-	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * and returns an ID for the contact.
+	 * 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.
 	 */
-	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			@Nullable PublicKey handshake, boolean verified) throws DbException;
+	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 with the given pseudonym and returns an ID for the
+	 * contact.
+	 */
+	ContactId addContact(Transaction txn, Author a, boolean verified)
+			throws DbException;
 
 	/**
 	 * Stores a group.
@@ -70,15 +114,29 @@ public interface DatabaseComponent extends TransactionManager {
 	void addGroup(Transaction txn, Group g) throws DbException;
 
 	/**
-	 * Stores an identity.
+	 * Stores the given handshake keys for the given contact and returns a
+	 * key set ID.
 	 */
-	void addIdentity(Transaction txn, Identity i) throws DbException;
+	HandshakeKeySetId addHandshakeKeys(Transaction txn, ContactId c,
+			HandshakeKeys k) throws DbException;
+
+	/**
+	 * Stores the given handshake keys for the given pending contact and
+	 * returns a key set ID.
+	 */
+	HandshakeKeySetId addHandshakeKeys(Transaction txn, PendingContactId p,
+			HandshakeKeys k) throws DbException;
+
+	/**
+	 * Stores a local pseudonym.
+	 */
+	void addLocalAuthor(Transaction txn, LocalAuthor a) throws DbException;
 
 	/**
 	 * Stores a local message.
 	 */
 	void addLocalMessage(Transaction txn, Message m, Metadata meta,
-			boolean shared, boolean temporary) throws DbException;
+			boolean shared) throws DbException;
 
 	/**
 	 * Stores a pending contact.
@@ -96,24 +154,15 @@ public interface DatabaseComponent extends TransactionManager {
 	 * Stores the given transport keys for the given contact and returns a
 	 * key set ID.
 	 */
-	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,
+	TransportKeySetId addTransportKeys(Transaction txn, ContactId c,
 			TransportKeys k) throws DbException;
 
 	/**
-	 * Returns true if the database contains the given contact for the given
-	 * local pseudonym.
+	 * Returns true if the database contains the given contact.
 	 * <p/>
 	 * Read-only.
 	 */
-	boolean containsContact(Transaction txn, AuthorId remote, AuthorId local)
-			throws DbException;
+	boolean containsContact(Transaction txn, AuthorId a) throws DbException;
 
 	/**
 	 * Returns true if the database contains the given group.
@@ -123,12 +172,12 @@ public interface DatabaseComponent extends TransactionManager {
 	boolean containsGroup(Transaction txn, GroupId g) throws DbException;
 
 	/**
-	 * Returns true if the database contains an identity for the given
-	 * pseudonym.
+	 * Returns true if the database contains the given local author.
 	 * <p/>
 	 * Read-only.
 	 */
-	boolean containsIdentity(Transaction txn, AuthorId a) throws DbException;
+	boolean containsLocalAuthor(Transaction txn, AuthorId local)
+			throws DbException;
 
 	/**
 	 * Returns true if the database contains the given pending contact.
@@ -203,6 +252,13 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	Contact getContact(Transaction txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns the contact with the given author ID.
+	 * <p/>
+	 * Read-only.
+	 */
+	Contact getContact(Transaction txn, AuthorId a) throws DbException;
+
 	/**
 	 * Returns all contacts.
 	 * <p/>
@@ -210,22 +266,6 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	Collection<Contact> getContacts(Transaction txn) throws DbException;
 
-	/**
-	 * Returns a possibly empty collection of contacts with the given author ID.
-	 * <p/>
-	 * Read-only.
-	 */
-	Collection<Contact> getContactsByAuthorId(Transaction txn, AuthorId remote)
-			throws DbException;
-
-	/**
-	 * Returns all contacts associated with the given local pseudonym.
-	 * <p/>
-	 * Read-only.
-	 */
-	Collection<ContactId> getContacts(Transaction txn, AuthorId local)
-			throws DbException;
-
 	/**
 	 * Returns the group with the given ID.
 	 * <p/>
@@ -258,18 +298,26 @@ public interface DatabaseComponent extends TransactionManager {
 			throws DbException;
 
 	/**
-	 * Returns the identity for the local pseudonym with the given ID.
+	 * Returns all handshake keys for the given transport.
 	 * <p/>
 	 * Read-only.
 	 */
-	Identity getIdentity(Transaction txn, AuthorId a) throws DbException;
+	Collection<HandshakeKeySet> getHandshakeKeys(Transaction txn, TransportId t)
+			throws DbException;
 
 	/**
-	 * Returns the identities for all local pseudonyms.
+	 * Returns the local pseudonym with the given ID.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<Identity> getIdentities(Transaction txn) throws DbException;
+	LocalAuthor getLocalAuthor(Transaction txn, AuthorId a) throws DbException;
+
+	/**
+	 * Returns all local pseudonyms.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<LocalAuthor> getLocalAuthors(Transaction txn) throws DbException;
 
 	/**
 	 * Returns the message with the given ID.
@@ -405,14 +453,6 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	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/>
@@ -428,13 +468,6 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	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/>
@@ -443,11 +476,17 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<TransportKeySet> getTransportKeys(Transaction txn, TransportId t)
 			throws DbException;
 
+	/**
+	 * Increments the outgoing stream counter for the given handshake keys.
+	 */
+	void incrementStreamCounter(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
-	void incrementStreamCounter(Transaction txn, TransportId t, KeySetId k)
-			throws DbException;
+	void incrementStreamCounter(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Merges the given metadata with the existing metadata for the given
@@ -503,9 +542,15 @@ public interface DatabaseComponent extends TransactionManager {
 	void removeGroup(Transaction txn, Group g) throws DbException;
 
 	/**
-	 * Removes an identity (and all associated state) from the database.
+	 * Removes the given handshake keys from the database.
 	 */
-	void removeIdentity(Transaction txn, AuthorId a) throws DbException;
+	void removeHandshakeKeys(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
+	/**
+	 * Removes a local pseudonym (and all associated state) from the database.
+	 */
+	void removeLocalAuthor(Transaction txn, AuthorId a) throws DbException;
 
 	/**
 	 * Removes a message (and all associated state) from the database.
@@ -518,12 +563,6 @@ public interface DatabaseComponent extends TransactionManager {
 	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.
 	 */
@@ -532,8 +571,8 @@ public interface DatabaseComponent extends TransactionManager {
 	/**
 	 * Removes the given transport keys from the database.
 	 */
-	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
-			throws DbException;
+	void removeTransportKeys(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Marks the given contact as verified.
@@ -552,11 +591,6 @@ public interface DatabaseComponent extends TransactionManager {
 	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.
 	 */
@@ -575,28 +609,31 @@ public interface DatabaseComponent extends TransactionManager {
 			Collection<MessageId> dependencies) throws DbException;
 
 	/**
-	 * 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
+	 * Sets the reordering window for the given transport key set in the given
 	 * time period.
 	 */
-	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
-			long timePeriod, long base, byte[] bitmap) throws DbException;
+	void setReorderingWindow(Transaction txn, TransportKeySetId k,
+			TransportId t, long timePeriod, long base, byte[] bitmap)
+			throws DbException;
 
 	/**
-	 * Sets the versions of the sync protocol supported by the given contact.
+	 * Sets the reordering window for the given handshake key set in the given
+	 * time period.
 	 */
-	void setSyncVersions(Transaction txn, ContactId c, List<Byte> supported)
+	void setReorderingWindow(Transaction txn, HandshakeKeySetId k,
+			TransportId t, long timePeriod, long base, byte[] bitmap)
 			throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
-	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
+	void setTransportKeysActive(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
+
+	/**
+	 * Stores the given handshake keys, deleting any keys they have replaced.
+	 */
+	void updateHandshakeKeys(Transaction txn, Collection<HandshakeKeySet> keys)
 			throws DbException;
 
 	/**

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

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

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

@@ -1,54 +0,0 @@
-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/identity/Author.java

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

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

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

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

@@ -1,88 +0,0 @@
-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 an identity with the given name. The identity includes a
-	 * handshake key pair.
+	 * Creates a local identity with the given name.
 	 */
 	@CryptoExecutor
-	Identity createIdentity(String name);
+	LocalAuthor createLocalAuthor(String name);
 
 	/**
-	 * 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.
+	 * Registers the given local identity with the manager. The identity is
+	 * not stored until {@link #storeLocalAuthor()} is called.
 	 */
-	void registerIdentity(Identity i);
+	void registerLocalAuthor(LocalAuthor a);
+
+	/**
+	 * Stores the local identity registered with
+	 * {@link #registerLocalAuthor(LocalAuthor)}, if any.
+	 */
+	void storeLocalAuthor() throws DbException;
 
 	/**
 	 * Returns the cached local identity or loads it from the database.
@@ -33,15 +33,7 @@ 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

@@ -1,12 +1,11 @@
 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_SIGNATURE;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 
 /**
  * A pseudonym for the local user.
@@ -15,20 +14,62 @@ import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNA
 @NotNullByDefault
 public class LocalAuthor extends Author {
 
-	private final PrivateKey privateKey;
+	private final byte[] privateKey;
+	@Nullable
+	private final byte[] handshakePublicKey, handshakePrivateKey;
+	private final long created;
 
 	public LocalAuthor(AuthorId id, int formatVersion, String name,
-			PublicKey publicKey, PrivateKey privateKey) {
+			byte[] publicKey, byte[] privateKey, long created) {
 		super(id, formatVersion, name, publicKey);
-		if (!privateKey.getKeyType().equals(KEY_TYPE_SIGNATURE))
-			throw new IllegalArgumentException();
 		this.privateKey = privateKey;
+		this.created = created;
+		handshakePublicKey = null;
+		handshakePrivateKey = null;
+	}
+
+	public LocalAuthor(AuthorId id, int formatVersion, String name,
+			byte[] publicKey, byte[] privateKey, byte[] handshakePublicKey,
+			byte[] handshakePrivateKey, long created) {
+		super(id, formatVersion, name, publicKey);
+		if (handshakePublicKey.length == 0 ||
+				handshakePublicKey.length > MAX_PUBLIC_KEY_LENGTH) {
+			throw new IllegalArgumentException();
+		}
+		this.privateKey = privateKey;
+		this.handshakePublicKey = handshakePublicKey;
+		this.handshakePrivateKey = handshakePrivateKey;
+		this.created = created;
 	}
 
 	/**
 	 * Returns the private key used to generate the pseudonym's signatures.
 	 */
-	public PrivateKey getPrivateKey() {
+	public byte[] getPrivateKey() {
 		return privateKey;
 	}
+
+	/**
+	 * Returns the public key used for handshaking, or null if no key exists.
+	 */
+	@Nullable
+	public byte[] getHandshakePublicKey() {
+		return handshakePublicKey;
+	}
+
+	/**
+	 * Returns the private key used for handshaking, or null if no key exists.
+	 */
+	@Nullable
+	public byte[] getHandshakePrivateKey() {
+		return handshakePrivateKey;
+	}
+
+	/**
+	 * 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/LocalAuthorAddedEvent.java

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

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

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

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;
 
 /**
- * Accepts key agreement connections over a given transport.
+ * An class for managing a particular key agreement listener.
  */
 public abstract class KeyAgreementListener {
 

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

@@ -0,0 +1,20 @@
+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: opening and closing the
- * {@link DatabaseComponent} starting and stopping {@link Service Services},
- * and shutting down {@link ExecutorService ExecutorServices}.
+ * 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}.
  */
 @NotNullByDefault
 public interface LifecycleManager {
@@ -42,19 +42,18 @@ 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)}.
@@ -63,7 +62,7 @@ public interface LifecycleManager {
 
 	/**
 	 * Opens the {@link DatabaseComponent} using the given key and starts any
-	 * registered {@link Service Services}.
+	 * registered {@link Client Clients} and {@link Service Services}.
 	 */
 	StartResult startServices(SecretKey dbKey);
 
@@ -81,7 +80,8 @@ public interface LifecycleManager {
 
 	/**
 	 * Waits for the {@link DatabaseComponent} to be opened and all registered
-	 * {@link Service Services} to start before returning.
+	 * {@link Client Clients} and {@link Service Services} to start before
+	 * returning.
 	 */
 	void waitForStartup() throws InterruptedException;
 
@@ -97,13 +97,4 @@ 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

@@ -6,27 +6,10 @@ import javax.annotation.Nullable;
 public class NullSafety {
 
 	/**
-	 * Stand-in for {@code Objects.requireNonNull()}.
+	 * Stand-in for `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

@@ -1,28 +0,0 @@
-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

@@ -1,46 +1,17 @@
 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

@@ -1,14 +1,7 @@
 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;
 
@@ -18,50 +11,13 @@ 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.Pair;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.properties.TransportProperties;
 
-import java.util.Collection;
+import java.util.Map;
 
 @NotNullByDefault
 public interface Plugin {
@@ -51,9 +51,8 @@ public interface Plugin {
 	int getPollingInterval();
 
 	/**
-	 * Attempts to create connections using the given transport properties,
-	 * passing any created connections to the corresponding handlers.
+	 * Attempts to establish connections to the given contacts, passing any
+	 * created connections to the callback.
 	 */
-	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties);
+	void poll(Map<ContactId, TransportProperties> contacts);
 }

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 extends ConnectionHandler {
+public interface PluginCallback {
 
 	/**
 	 * Returns the plugin's settings

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

@@ -36,9 +36,4 @@ 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/duplex/DuplexPlugin.java

@@ -3,11 +3,8 @@ 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;
 
@@ -43,19 +40,4 @@ 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

@@ -0,0 +1,17 @@
+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

@@ -1,7 +1,6 @@
 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;
@@ -26,5 +25,5 @@ public interface DuplexPluginFactory {
 	 * Creates and returns a plugin, or null if no plugin can be created.
 	 */
 	@Nullable
-	DuplexPlugin createPlugin(PluginCallback callback);
+	DuplexPlugin createPlugin(DuplexPluginCallback callback);
 }

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

@@ -0,0 +1,19 @@
+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

@@ -1,7 +1,6 @@
 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;
@@ -26,5 +25,5 @@ public interface SimplexPluginFactory {
 	 * Creates and returns a plugin, or null if no plugin can be created.
 	 */
 	@Nullable
-	SimplexPlugin createPlugin(PluginCallback callback);
+	SimplexPlugin createPlugin(SimplexPluginCallback callback);
 }

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

@@ -1,14 +1,10 @@
 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 {
 
@@ -20,20 +16,5 @@ 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

@@ -1,15 +0,0 @@
-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

@@ -1,26 +0,0 @@
-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

@@ -1,12 +0,0 @@
-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

@@ -1,32 +0,0 @@
-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

@@ -1,25 +0,0 @@
-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

@@ -1,36 +0,0 @@
-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;
-	}
-}

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

@@ -1,16 +1,10 @@
 package org.briarproject.bramble.api.sync;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
 import java.util.Collection;
 
-import javax.annotation.concurrent.Immutable;
-
 /**
  * A record acknowledging receipt of one or more {@link Message Messages}.
  */
-@Immutable
-@NotNullByDefault
 public class Ack {
 
 	private final Collection<MessageId> acked;

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

@@ -0,0 +1,14 @@
+package org.briarproject.bramble.api.sync;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface Client {
+
+	/**
+	 * Called at startup to create any local state needed by the client.
+	 */
+	void createLocalState(Transaction txn) throws DbException;
+}

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

@@ -1,14 +1,8 @@
 package org.briarproject.bramble.api.sync;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.concurrent.Immutable;
-
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 
-@Immutable
-@NotNullByDefault
 public class Message {
 
 	/**

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

@@ -1,16 +1,10 @@
 package org.briarproject.bramble.api.sync;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
 import java.util.Collection;
 
-import javax.annotation.concurrent.Immutable;
-
 /**
  * A record offering the recipient one or more {@link Message Messages}.
  */
-@Immutable
-@NotNullByDefault
 public class Offer {
 
 	private final Collection<MessageId> offered;

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

@@ -9,5 +9,5 @@ public interface RecordTypes {
 	byte MESSAGE = 1;
 	byte OFFER = 2;
 	byte REQUEST = 3;
-	byte VERSIONS = 4;
+
 }

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

@@ -1,16 +1,10 @@
 package org.briarproject.bramble.api.sync;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
 import java.util.Collection;
 
-import javax.annotation.concurrent.Immutable;
-
 /**
  * A record requesting one or more {@link Message Messages} from the recipient.
  */
-@Immutable
-@NotNullByDefault
 public class Request {
 
 	private final Collection<MessageId> requested;

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

@@ -2,9 +2,6 @@ package org.briarproject.bramble.api.sync;
 
 import org.briarproject.bramble.api.UniqueId;
 
-import java.util.List;
-
-import static java.util.Collections.singletonList;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 
 public interface SyncConstants {
@@ -14,11 +11,6 @@ public interface SyncConstants {
 	 */
 	byte PROTOCOL_VERSION = 0;
 
-	/**
-	 * The versions of the sync protocol this peer supports.
-	 */
-	List<Byte> SUPPORTED_VERSIONS = singletonList(PROTOCOL_VERSION);
-
 	/**
 	 * The maximum length of a group descriptor in bytes.
 	 */
@@ -43,10 +35,4 @@ public interface SyncConstants {
 	 * The maximum number of message IDs in an ack, offer or request record.
 	 */
 	int MAX_MESSAGE_IDS = MAX_RECORD_PAYLOAD_BYTES / UniqueId.LENGTH;
-
-	/**
-	 * The maximum number of versions of the sync protocol a peer may support
-	 * simultaneously.
-	 */
-	int MAX_SUPPORTED_VERSIONS = 10;
 }

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

@@ -25,7 +25,4 @@ public interface SyncRecordReader {
 
 	Request readRequest() throws IOException;
 
-	boolean hasVersions() throws IOException;
-
-	Versions readVersions() throws IOException;
 }

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

@@ -15,7 +15,5 @@ public interface SyncRecordWriter {
 
 	void writeRequest(Request r) throws IOException;
 
-	void writeVersions(Versions v) throws IOException;
-
 	void flush() throws IOException;
 }

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

@@ -1,26 +0,0 @@
-package org.briarproject.bramble.api.sync;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.List;
-
-import javax.annotation.concurrent.Immutable;
-
-/**
- * A record telling the recipient which versions of the sync protocol the
- * sender supports.
- */
-@Immutable
-@NotNullByDefault
-public class Versions {
-
-	private final List<Byte> supported;
-
-	public Versions(List<Byte> supported) {
-		this.supported = supported;
-	}
-
-	public List<Byte> getSupportedVersions() {
-		return supported;
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/event/SyncVersionsUpdatedEvent.java

@@ -1,34 +0,0 @@
-package org.briarproject.bramble.api.sync.event;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.List;
-
-import javax.annotation.concurrent.Immutable;
-
-/**
- * An event that is broadcast when the versions of the sync protocol supported
- * by a contact are updated.
- */
-@Immutable
-@NotNullByDefault
-public class SyncVersionsUpdatedEvent extends Event {
-
-	private final ContactId contactId;
-	private final List<Byte> supported;
-
-	public SyncVersionsUpdatedEvent(ContactId contactId, List<Byte> supported) {
-		this.contactId = contactId;
-		this.supported = supported;
-	}
-
-	public ContactId getContactId() {
-		return contactId;
-	}
-
-	public List<Byte> getSupportedVersions() {
-		return supported;
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/IncomingMessageHook.java

@@ -11,8 +11,7 @@ public interface IncomingMessageHook {
 	/**
 	 * Called once for each incoming message that passes validation.
 	 *
-	 * @param txn A read-write transaction
-	 * @return Whether or not this message should be shared
+	 * @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 an InvalidMessageException is thrown,

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

@@ -0,0 +1,57 @@
+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Abstract superclass for {@link TransportKeys} and {@link HandshakeKeys}.
+ */
+@Immutable
+@NotNullByDefault
+public abstract class AbstractTransportKeys {
+
+	private final TransportId transportId;
+	private final IncomingKeys inPrev, inCurr, inNext;
+	private final OutgoingKeys outCurr;
+
+	AbstractTransportKeys(TransportId transportId, IncomingKeys inPrev,
+			IncomingKeys inCurr, IncomingKeys inNext, OutgoingKeys outCurr) {
+		if (inPrev.getTimePeriod() != outCurr.getTimePeriod() - 1)
+			throw new IllegalArgumentException();
+		if (inCurr.getTimePeriod() != outCurr.getTimePeriod())
+			throw new IllegalArgumentException();
+		if (inNext.getTimePeriod() != outCurr.getTimePeriod() + 1)
+			throw new IllegalArgumentException();
+		this.transportId = transportId;
+		this.inPrev = inPrev;
+		this.inCurr = inCurr;
+		this.inNext = inNext;
+		this.outCurr = outCurr;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public IncomingKeys getPreviousIncomingKeys() {
+		return inPrev;
+	}
+
+	public IncomingKeys getCurrentIncomingKeys() {
+		return inCurr;
+	}
+
+	public IncomingKeys getNextIncomingKeys() {
+		return inNext;
+	}
+
+	public OutgoingKeys getCurrentOutgoingKeys() {
+		return outCurr;
+	}
+
+	public long getTimePeriod() {
+		return outCurr.getTimePeriod();
+	}
+}

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

@@ -0,0 +1,70 @@
+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A set of keys for handshaking with a given contact or pending contact over a
+ * given transport. Unlike a {@link TransportKeySet} these keys do not provide
+ * forward secrecy.
+ */
+@Immutable
+@NotNullByDefault
+public class HandshakeKeySet {
+
+	private final HandshakeKeySetId keySetId;
+	@Nullable
+	private final ContactId contactId;
+	@Nullable
+	private final PendingContactId pendingContactId;
+	private final HandshakeKeys keys;
+
+	public HandshakeKeySet(HandshakeKeySetId keySetId, ContactId contactId,
+			HandshakeKeys keys) {
+		this.keySetId = keySetId;
+		this.contactId = contactId;
+		this.keys = keys;
+		pendingContactId = null;
+	}
+
+	public HandshakeKeySet(HandshakeKeySetId keySetId,
+			PendingContactId pendingContactId, HandshakeKeys keys) {
+		this.keySetId = keySetId;
+		this.pendingContactId = pendingContactId;
+		this.keys = keys;
+		contactId = null;
+	}
+
+	public HandshakeKeySetId getKeySetId() {
+		return keySetId;
+	}
+
+	@Nullable
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	@Nullable
+	public PendingContactId getPendingContactId() {
+		return pendingContactId;
+	}
+
+	public HandshakeKeys getKeys() {
+		return keys;
+	}
+
+	@Override
+	public int hashCode() {
+		return keySetId.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof HandshakeKeySet &&
+				keySetId.equals(((HandshakeKeySet) o).keySetId);
+	}
+}

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

@@ -5,16 +5,17 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * Type-safe wrapper for an integer that uniquely identifies a set of
- * {@link TransportKeySet transport keys} within the scope of the local device.
+ * Type-safe wrapper for an integer that uniquely identifies a
+ * {@link HandshakeKeySet set of handshake keys} within the scope of the local
+ * device.
  */
 @Immutable
 @NotNullByDefault
-public class KeySetId {
+public class HandshakeKeySetId {
 
 	private final int id;
 
-	public KeySetId(int id) {
+	public HandshakeKeySetId(int id) {
 		this.id = id;
 	}
 
@@ -29,6 +30,7 @@ public class KeySetId {
 
 	@Override
 	public boolean equals(Object o) {
-		return o instanceof KeySetId && id == ((KeySetId) o).id;
+		return o instanceof HandshakeKeySetId &&
+				id == ((HandshakeKeySetId) o).id;
 	}
 }

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

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Keys for handshaking with a given contact or pending contact over a given
+ * transport. Unlike {@link TransportKeys} these keys do not provide forward
+ * secrecy.
+ */
+@Immutable
+@NotNullByDefault
+public class HandshakeKeys extends AbstractTransportKeys {
+
+	private final SecretKey rootKey;
+	private final boolean alice;
+
+	public HandshakeKeys(TransportId transportId, IncomingKeys inPrev,
+			IncomingKeys inCurr, IncomingKeys inNext, OutgoingKeys outCurr,
+			SecretKey rootKey, boolean alice) {
+		super(transportId, inPrev, inCurr, inNext, outCurr);
+		this.rootKey = rootKey;
+		this.alice = alice;
+	}
+
+	public SecretKey getRootKey() {
+		return rootKey;
+	}
+
+	public boolean isAlice() {
+		return alice;
+	}
+}