add kobakei library to witness

.idea/codeStyles/Project.xml

@@ -36,9 +36,31 @@
       <option name="JD_ALIGN_PARAM_COMMENTS" value="false" />
       <option name="JD_ALIGN_EXCEPTION_COMMENTS" value="false" />
     </JavaCodeStyleSettings>
-    <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>
@@ -235,11 +257,5 @@
         </rules>
       </arrangement>
     </codeStyleSettings>
-    <codeStyleSettings language="kotlin">
-      <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
-      <option name="PARAMETER_ANNOTATION_WRAP" value="1" />
-      <option name="VARIABLE_ANNOTATION_WRAP" value="1" />
-      <option name="ENUM_CONSTANTS_WRAP" value="1" />
-    </codeStyleSettings>
   </code_scheme>
 </component>

.idea/runConfigurations/All_in_briar_headless.xml

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

.idea/runConfigurations/All_tests.xml

@@ -24,7 +24,6 @@
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-android" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in bramble-java" run_configuration_type="AndroidJUnit" />
       <option name="RunConfigurationTask" enabled="true" run_configuration_name="All tests in briar-core" run_configuration_type="AndroidJUnit" />
-      <option name="RunConfigurationTask" enabled="true" run_configuration_name="All in briar-headless" run_configuration_type="AndroidJUnit" />
     </method>
   </configuration>
-</component>
+</component>

.idea/runConfigurations/briar_headless.xml

@@ -1,17 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="briar-headless" type="JetRunConfigurationType" factoryName="Kotlin" singleton="true">
-    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
-    <option name="VM_PARAMETERS" value="" />
-    <option name="PROGRAM_PARAMETERS" value="-v" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
-    <option name="PASS_PARENT_ENVS" value="true" />
-    <option name="MAIN_CLASS_NAME" value="org.briarproject.briar.headless.MainKt" />
-    <option name="WORKING_DIRECTORY" value="" />
-    <module name="briar-headless" />
-    <envs />
-    <method>
-      <option name="Gradle.BeforeRunTask" enabled="true" tasks="jar" externalProjectPath="$PROJECT_DIR$/briar-headless" vmOptions="" scriptParameters="" />
-    </method>
-  </configuration>
-</component>

bramble-android/build.gradle

@@ -1,18 +1,16 @@
-import com.android.build.gradle.tasks.MergeResources
-
 apply plugin: 'com.android.library'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion 28
-	buildToolsVersion '28.0.3'
+	compileSdkVersion 27
+	buildToolsVersion '27.0.3'
 
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 10106
-		versionName "1.1.6"
+		versionCode 10101
+		versionName "1.1.1"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -30,10 +28,9 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.9@zip'
+	tor 'org.briarproject:tor-android:0.2.9.16@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.0.2'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
@@ -42,29 +39,13 @@ dependencies {
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	testImplementation "org.hamcrest:hamcrest-library:1.3"
+	testImplementation "org.hamcrest:hamcrest-core:1.3"
 }
 
-def torBinariesDir = 'src/main/res/raw'
-
-task cleanTorBinaries {
-	doLast {
-		delete fileTree(torBinariesDir) { include '*.zip' }
+project.afterEvaluate {
+	copy {
+		from configurations.tor.collect { zipTree(it) }
+		into 'src/main/res/raw'
 	}
 }
-
-clean.dependsOn cleanTorBinaries
-
-task unpackTorBinaries {
-	doLast {
-		copy {
-			from configurations.tor.collect { zipTree(it) }
-			into torBinariesDir
-		}
-	}
-	dependsOn cleanTorBinaries
-}
-
-tasks.withType(MergeResources) {
-	inputs.dir torBinariesDir
-	dependsOn unpackTorBinaries
-}

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

@@ -1,11 +0,0 @@
-package org.briarproject.bramble;
-
-import org.briarproject.bramble.battery.AndroidBatteryModule;
-import org.briarproject.bramble.network.AndroidNetworkModule;
-
-public interface BrambleAndroidEagerSingletons {
-
-	void inject(AndroidBatteryModule.EagerSingletons init);
-
-	void inject(AndroidNetworkModule.EagerSingletons init);
-}

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

@@ -1,6 +1,5 @@
 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.system.AndroidSystemModule;
@@ -8,15 +7,10 @@ import org.briarproject.bramble.system.AndroidSystemModule;
 import dagger.Module;
 
 @Module(includes = {
-		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
 		CircumventionModule.class
 })
 public class BrambleAndroidModule {
 
-	public static void initEagerSingletons(BrambleAndroidEagerSingletons c) {
-		c.inject(new AndroidBatteryModule.EagerSingletons());
-		c.inject(new AndroidNetworkModule.EagerSingletons());
-	}
 }

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

@@ -12,15 +12,11 @@ import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
-import java.util.HashSet;
-import java.util.Set;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static android.os.Build.VERSION.SDK_INT;
-
 class AndroidAccountManager extends AccountManagerImpl
 		implements AccountManager {
 
@@ -93,42 +89,20 @@ class AndroidAccountManager extends AccountManagerImpl
 				LOG.warning("Could not clear shared preferences");
 		}
 		// Delete files, except lib and shared_prefs directories
-		Set<File> files = new HashSet<>();
 		File dataDir = new File(appContext.getApplicationInfo().dataDir);
-		@Nullable
-		File[] fileArray = dataDir.listFiles();
-		if (fileArray == null) {
+		File[] children = dataDir.listFiles();
+		if (children == null) {
 			LOG.warning("Could not list files in app data dir");
 		} else {
-			for (File file : fileArray) {
-				String name = file.getName();
+			for (File child : children) {
+				String name = child.getName();
 				if (!name.equals("lib") && !name.equals("shared_prefs")) {
-					files.add(file);
+					IoUtils.deleteFileOrDir(child);
 				}
 			}
 		}
-		files.add(appContext.getFilesDir());
-		files.add(appContext.getCacheDir());
-		addIfNotNull(files, appContext.getExternalCacheDir());
-		if (SDK_INT >= 19) {
-			for (File file : appContext.getExternalCacheDirs()) {
-				addIfNotNull(files, file);
-			}
-		}
-		if (SDK_INT >= 21) {
-			for (File file : appContext.getExternalMediaDirs()) {
-				addIfNotNull(files, file);
-			}
-		}
-		for (File file : files) {
-			IoUtils.deleteFileOrDir(file);
-		}
 		// Recreate the cache dir as some OpenGL drivers expect it to exist
-		if (!new File(dataDir, "cache").mkdirs())
+		if (!new File(dataDir, "cache").mkdir())
 			LOG.warning("Could not recreate cache dir");
 	}
-
-	private void addIfNotNull(Set<File> files, @Nullable File file) {
-		if (file != null) files.add(file);
-	}
 }

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

@@ -1,81 +0,0 @@
-package org.briarproject.bramble.battery;
-
-import android.app.Application;
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-
-import org.briarproject.bramble.api.battery.BatteryManager;
-import org.briarproject.bramble.api.battery.event.BatteryEvent;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.Service;
-
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import static android.content.Intent.ACTION_BATTERY_CHANGED;
-import static android.content.Intent.ACTION_POWER_CONNECTED;
-import static android.content.Intent.ACTION_POWER_DISCONNECTED;
-import static android.os.BatteryManager.EXTRA_PLUGGED;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
-
-class AndroidBatteryManager implements BatteryManager, Service {
-
-	private static final Logger LOG =
-			getLogger(AndroidBatteryManager.class.getName());
-
-	private final Context appContext;
-	private final EventBus eventBus;
-	private final AtomicBoolean used = new AtomicBoolean(false);
-
-	private volatile BroadcastReceiver batteryReceiver = null;
-
-	@Inject
-	AndroidBatteryManager(Application app, EventBus eventBus) {
-		this.appContext = app.getApplicationContext();
-		this.eventBus = eventBus;
-	}
-
-	@Override
-	public boolean isCharging() {
-		// Get the sticky intent for ACTION_BATTERY_CHANGED
-		IntentFilter filter = new IntentFilter(ACTION_BATTERY_CHANGED);
-		Intent i = appContext.registerReceiver(null, filter);
-		if (i == null) return false;
-		int status = i.getIntExtra(EXTRA_PLUGGED, 0);
-		return status != 0;
-	}
-
-	@Override
-	public void startService() {
-		if (used.getAndSet(true)) throw new IllegalStateException();
-		batteryReceiver = new BatteryReceiver();
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_POWER_CONNECTED);
-		filter.addAction(ACTION_POWER_DISCONNECTED);
-		appContext.registerReceiver(batteryReceiver, filter);
-	}
-
-	@Override
-	public void stopService() {
-		if (batteryReceiver != null)
-			appContext.unregisterReceiver(batteryReceiver);
-	}
-
-	private class BatteryReceiver extends BroadcastReceiver {
-
-		@Override
-		public void onReceive(Context ctx, Intent i) {
-			String action = i.getAction();
-			if (LOG.isLoggable(INFO)) LOG.info("Received broadcast " + action);
-			if (ACTION_POWER_CONNECTED.equals(action))
-				eventBus.broadcast(new BatteryEvent(true));
-			else if (ACTION_POWER_DISCONNECTED.equals(action))
-				eventBus.broadcast(new BatteryEvent(false));
-		}
-	}
-}

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

@@ -1,27 +0,0 @@
-package org.briarproject.bramble.battery;
-
-import org.briarproject.bramble.api.battery.BatteryManager;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-
-import javax.inject.Inject;
-import javax.inject.Singleton;
-
-import dagger.Module;
-import dagger.Provides;
-
-@Module
-public class AndroidBatteryModule {
-
-	public static class EagerSingletons {
-		@Inject
-		BatteryManager batteryManager;
-	}
-
-	@Provides
-	@Singleton
-	BatteryManager provideBatteryManager(LifecycleManager lifecycleManager,
-			AndroidBatteryManager batteryManager) {
-		lifecycleManager.registerService(batteryManager);
-		return batteryManager;
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/network/AndroidNetworkModule.java

@@ -3,7 +3,6 @@ package org.briarproject.bramble.network;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 
-import javax.inject.Inject;
 import javax.inject.Singleton;
 
 import dagger.Module;
@@ -12,11 +11,6 @@ import dagger.Provides;
 @Module
 public class AndroidNetworkModule {
 
-	public static class EagerSingletons {
-		@Inject
-		NetworkManager networkManager;
-	}
-
 	@Provides
 	@Singleton
 	NetworkManager provideNetworkManager(LifecycleManager lifecycleManager,

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

@@ -16,27 +16,18 @@ 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;
 import org.briarproject.bramble.util.AndroidUtils;
-import org.briarproject.bramble.util.IoUtils;
 
+import java.io.Closeable;
 import java.io.IOException;
 import java.security.SecureRandom;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.List;
 import java.util.UUID;
-import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
-import java.util.concurrent.LinkedBlockingQueue;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
-import static android.bluetooth.BluetoothAdapter.ACTION_DISCOVERY_FINISHED;
-import static android.bluetooth.BluetoothAdapter.ACTION_DISCOVERY_STARTED;
 import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
 import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
 import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
@@ -46,12 +37,8 @@ import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERA
 import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
 import static android.bluetooth.BluetoothAdapter.STATE_OFF;
 import static android.bluetooth.BluetoothAdapter.STATE_ON;
-import static android.bluetooth.BluetoothDevice.ACTION_FOUND;
-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 org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -60,11 +47,8 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private static final Logger LOG =
 			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
 
-	private static final int MAX_DISCOVERY_MS = 10_000;
-
 	private final AndroidExecutor androidExecutor;
 	private final Context appContext;
-	private final Clock clock;
 
 	private volatile boolean wasEnabledByUs = false;
 	private volatile BluetoothStateReceiver receiver = null;
@@ -74,13 +58,12 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
 			Executor ioExecutor, AndroidExecutor androidExecutor,
-			Context appContext, SecureRandom secureRandom, Clock clock,
-			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
+			Context appContext, SecureRandom secureRandom, Backoff backoff,
+			DuplexPluginCallback callback, int maxLatency) {
 		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
 				maxLatency);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
-		this.clock = clock;
 	}
 
 	@Override
@@ -160,7 +143,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	@Override
 	void tryToClose(@Nullable BluetoothServerSocket ss) {
-		IoUtils.tryToClose(ss, LOG, WARNING);
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
 	}
 
 	@Override
@@ -190,77 +177,17 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			s.connect();
 			return wrapSocket(s);
 		} catch (IOException e) {
-			IoUtils.tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			throw e;
 		}
 	}
 
-	@Override
-	@Nullable
-	DuplexTransportConnection discoverAndConnect(String uuid) {
-		if (adapter == null) return null;
-		for (String address : discoverDevices()) {
-			try {
-				if (LOG.isLoggable(INFO))
-					LOG.info("Connecting to " + scrubMacAddress(address));
-				return connectTo(address, uuid);
-			} catch (IOException e) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Could not connect to "
-							+ scrubMacAddress(address));
-				}
-			}
-		}
-		LOG.info("Could not connect to any devices");
-		return null;
-	}
-
-	private Collection<String> discoverDevices() {
-		List<String> addresses = new ArrayList<>();
-		BlockingQueue<Intent> intents = new LinkedBlockingQueue<>();
-		DiscoveryReceiver receiver = new DiscoveryReceiver(intents);
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_DISCOVERY_STARTED);
-		filter.addAction(ACTION_DISCOVERY_FINISHED);
-		filter.addAction(ACTION_FOUND);
-		appContext.registerReceiver(receiver, filter);
+	private void tryToClose(@Nullable Closeable c) {
 		try {
-			if (adapter.startDiscovery()) {
-				long now = clock.currentTimeMillis();
-				long end = now + MAX_DISCOVERY_MS;
-				while (now < end) {
-					Intent i = intents.poll(end - now, MILLISECONDS);
-					if (i == null) break;
-					String action = i.getAction();
-					if (ACTION_DISCOVERY_STARTED.equals(action)) {
-						LOG.info("Discovery started");
-					} else if (ACTION_DISCOVERY_FINISHED.equals(action)) {
-						LOG.info("Discovery finished");
-						break;
-					} else if (ACTION_FOUND.equals(action)) {
-						BluetoothDevice d = i.getParcelableExtra(EXTRA_DEVICE);
-						String address = d.getAddress();
-						if (LOG.isLoggable(INFO))
-							LOG.info("Discovered " + scrubMacAddress(address));
-						if (!addresses.contains(address))
-							addresses.add(address);
-					}
-					now = clock.currentTimeMillis();
-				}
-			} else {
-				LOG.info("Could not start discovery");
-			}
-		} catch (InterruptedException e) {
-			LOG.info("Interrupted while discovering devices");
-			Thread.currentThread().interrupt();
-		} finally {
-			LOG.info("Cancelling discovery");
-			adapter.cancelDiscovery();
-			appContext.unregisterReceiver(receiver);
+			if (c != null) c.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
 		}
-		// Shuffle the addresses so we don't always try the same one first
-		Collections.shuffle(addresses);
-		return addresses;
 	}
 
 	private class BluetoothStateReceiver extends BroadcastReceiver {
@@ -280,18 +207,4 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			}
 		}
 	}
-
-	private static class DiscoveryReceiver extends BroadcastReceiver {
-
-		private final BlockingQueue<Intent> intents;
-
-		private DiscoveryReceiver(BlockingQueue<Intent> intents) {
-			this.intents = intents;
-		}
-
-		@Override
-		public void onReceive(Context ctx, Intent intent) {
-			intents.add(intent);
-		}
-	}
 }

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

@@ -11,7 +11,6 @@ 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;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
@@ -34,19 +33,17 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	private final Context appContext;
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
-	private final Clock clock;
 	private final BackoffFactory backoffFactory;
 
 	public AndroidBluetoothPluginFactory(Executor ioExecutor,
 			AndroidExecutor androidExecutor, Context appContext,
-			SecureRandom secureRandom, EventBus eventBus, Clock clock,
+			SecureRandom secureRandom, EventBus eventBus,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
-		this.clock = clock;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -68,7 +65,7 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
 				connectionLimiter, ioExecutor, androidExecutor, appContext,
-				secureRandom, clock, backoff, callback, MAX_LATENCY);
+				secureRandom, backoff, callback, MAX_LATENCY);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -6,7 +6,6 @@ import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.PowerManager;
 
-import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -42,18 +41,17 @@ class AndroidTorPlugin extends TorPlugin {
 			Context appContext, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager, Backoff backoff,
+			CircumventionProvider circumventionProvider, Backoff backoff,
 			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
-				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, callback, architecture, maxLatency, maxIdleTime,
+				clock, resourceProvider, circumventionProvider, backoff,
+				callback, architecture, maxLatency, maxIdleTime,
 				appContext.getDir("tor", MODE_PRIVATE));
 		this.appContext = appContext;
 		PowerManager pm = (PowerManager)
 				appContext.getSystemService(POWER_SERVICE);
-		if (pm == null) throw new AssertionError();
+		assert pm != null;
 		wakeLock = new RenewableWakeLock(pm, scheduler, PARTIAL_WAKE_LOCK,
 				WAKE_LOCK_TAG, 1, MINUTES);
 	}

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

@@ -3,7 +3,6 @@ package org.briarproject.bramble.plugin.tor;
 import android.content.Context;
 import android.os.Build;
 
-import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -49,7 +48,6 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	private final BackoffFactory backoffFactory;
 	private final ResourceProvider resourceProvider;
 	private final CircumventionProvider circumventionProvider;
-	private final BatteryManager batteryManager;
 	private final Clock clock;
 
 	public AndroidTorPluginFactory(Executor ioExecutor,
@@ -57,8 +55,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			NetworkManager networkManager, LocationUtils locationUtils,
 			EventBus eventBus, SocketFactory torSocketFactory,
 			BackoffFactory backoffFactory, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager, Clock clock) {
+			CircumventionProvider circumventionProvider, Clock clock) {
 		this.ioExecutor = ioExecutor;
 		this.scheduler = scheduler;
 		this.appContext = appContext;
@@ -69,7 +66,6 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
-		this.batteryManager = batteryManager;
 		this.clock = clock;
 	}
 
@@ -108,8 +104,8 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor, scheduler,
 				appContext, networkManager, locationUtils, torSocketFactory,
-				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
+				clock, resourceProvider, circumventionProvider, backoff,
+				callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.system;
 
-import android.annotation.SuppressLint;
 import android.app.Application;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
@@ -27,7 +26,7 @@ import static android.provider.Settings.Secure.ANDROID_ID;
 
 @Immutable
 @NotNullByDefault
-class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
+class AndroidSecureRandomProvider extends LinuxSecureRandomProvider {
 
 	private static final int SEED_LENGTH = 32;
 
@@ -38,7 +37,6 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		appContext = app.getApplicationContext();
 	}
 
-	@SuppressLint("HardwareIds")
 	@Override
 	protected void writeToEntropyPool(DataOutputStream out) throws IOException {
 		super.writeToEntropyPool(out);
@@ -51,14 +49,12 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		String id = Settings.Secure.getString(contentResolver, ANDROID_ID);
 		if (id != null) out.writeUTF(id);
 		Parcel parcel = Parcel.obtain();
-		WifiManager wm = (WifiManager) appContext.getApplicationContext()
-				.getSystemService(WIFI_SERVICE);
-		if (wm != null) {
-			List<WifiConfiguration> configs = wm.getConfiguredNetworks();
-			if (configs != null) {
-				for (WifiConfiguration config : configs)
-					parcel.writeParcelable(config, 0);
-			}
+		WifiManager wm =
+				(WifiManager) appContext.getSystemService(WIFI_SERVICE);
+		List<WifiConfiguration> configs = wm.getConfiguredNetworks();
+		if (configs != null) {
+			for (WifiConfiguration config : configs)
+				parcel.writeParcelable(config, 0);
 		}
 		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
 		if (bt != null) {
@@ -81,13 +77,13 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 
 	// Based on https://android-developers.googleblog.com/2013/08/some-securerandom-thoughts.html
 	private void applyOpenSslFix() {
-		byte[] seed = new UnixSecureRandomSpi().engineGenerateSeed(
+		byte[] seed = new LinuxSecureRandomSpi().engineGenerateSeed(
 				SEED_LENGTH);
 		try {
 			// Seed the OpenSSL PRNG
 			Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
 					.getMethod("RAND_seed", byte[].class)
-					.invoke(null, (Object) seed);
+					.invoke(null, seed);
 			// Mix the output of the Linux PRNG into the OpenSSL PRNG
 			int bytesRead = (Integer) Class.forName(
 					"org.apache.harmony.xnet.provider.jsse.NativeCrypto")

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

@@ -11,12 +11,15 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
+import java.util.logging.Logger;
 
 import static android.content.Context.MODE_PRIVATE;
-import static android.os.Build.VERSION.SDK_INT;
 
 public class AndroidUtils {
 
+	private static final Logger LOG =
+			Logger.getLogger(AndroidUtils.class.getName());
+
 	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
 	private static final String FAKE_BLUETOOTH_ADDRESS = "02:00:00:00:00:00";
 
@@ -25,7 +28,7 @@ public class AndroidUtils {
 	@SuppressWarnings("deprecation")
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
-		if (SDK_INT >= 21) {
+		if (Build.VERSION.SDK_INT >= 21) {
 			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);

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

@@ -112,8 +112,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		// Other directories should be deleted
 		File potatoDir = new File(testDir, ".potato");
 		File potatoFile = new File(potatoDir, "file");
-		File filesDir = new File(testDir, "filesDir");
-		File externalCacheDir = new File(testDir, "externalCacheDir");
 
 		context.checking(new Expectations() {{
 			oneOf(prefs).edit();
@@ -130,12 +128,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 			will(returnValue(true));
 			oneOf(app).getApplicationInfo();
 			will(returnValue(applicationInfo));
-			oneOf(app).getFilesDir();
-			will(returnValue(filesDir));
-			oneOf(app).getCacheDir();
-			will(returnValue(cacheDir));
-			oneOf(app).getExternalCacheDir();
-			will(returnValue(externalCacheDir));
 		}});
 
 		assertTrue(dbDir.mkdirs());
@@ -148,8 +140,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		assertTrue(cacheFile.createNewFile());
 		assertTrue(potatoDir.mkdirs());
 		assertTrue(potatoFile.createNewFile());
-		assertTrue(filesDir.mkdirs());
-		assertTrue(externalCacheDir.mkdirs());
 
 		accountManager.deleteAccount();
 
@@ -163,8 +153,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		assertFalse(cacheFile.exists());
 		assertFalse(potatoDir.exists());
 		assertFalse(potatoFile.exists());
-		assertFalse(filesDir.exists());
-		assertFalse(externalCacheDir.exists());
 	}
 
 	@After

bramble-android/witness.gradle

@@ -1,56 +1,50 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        '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:aapt2:3.3.2-5309881:aapt2-3.3.2-5309881-linux.jar:9beead7e8b1057359049f450538aadcd3eb2a5bc3fbdd5e3296cb8fdc2a22412',
-        '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.android.tools.analytics-library:protos:26.1.3:protos-26.1.3.jar:818c9f256f141d9dafec03a1aa2b94d240b2c140acfd7ee31a8b3e6c2b9479e3',
+        'com.android.tools.analytics-library:shared:26.1.3:shared-26.1.3.jar:7110706c7ada96c8b6f5ca80c478291bc7899d46277de2c48527e045442401a3',
+        'com.android.tools.analytics-library:tracker:26.1.3:tracker-26.1.3.jar:4155424bf2ce4872da83332579a1707252bc66cbd77c5144fdc4483d0f2e1418',
+        'com.android.tools.build:apksig:3.1.3:apksig-3.1.3.jar:7e1f8e675a6e768e5b56405e41d6c3cc05befe62e601b04177de1029902c9c89',
+        'com.android.tools.build:builder-model:3.1.3:builder-model-3.1.3.jar:06ad1c422d679fc698451479cb40ba863849d67bfd1de23f6d2c16d78b024b0b',
+        'com.android.tools.build:builder-test-api:3.1.3:builder-test-api-3.1.3.jar:4d989f780436794f0f8b2f50e9e079b786571eac90f26c208ab2ae6d4012f389',
+        'com.android.tools.build:builder:3.1.3:builder-3.1.3.jar:8a1092012c89d0ec1ee2eff09c5708c71ef4482a6862df8d3a44a67fccace01c',
+        'com.android.tools.build:gradle-api:3.1.3:gradle-api-3.1.3.jar:01e4df521456aef66514336f1d492346730dd1fb8f6433a89f62da834941ed72',
+        'com.android.tools.build:manifest-merger:26.1.3:manifest-merger-26.1.3.jar:1e4fc7e932adb4607082409800e5e6fccb42e6c5360ae5990094bf522f3ada55',
+        'com.android.tools.ddms:ddmlib:26.1.3:ddmlib-26.1.3.jar:c54931cd68df5d1ea2923b3b320eae47cd2307a5a916bb8674c0acf93cd1d3cd',
+        'com.android.tools.external.com-intellij:intellij-core:26.1.3:intellij-core-26.1.3.jar:af67f5535fef2e1a28b1007a4acb8c5deb6a1e33b8afe7b11d012c9e778ebcec',
+        'com.android.tools.external.com-intellij:kotlin-compiler:26.1.3:kotlin-compiler-26.1.3.jar:c746d2859dc11cc05c84b692b3498d3a621e0929511f8440ee009c6557838fd4',
+        'com.android.tools.external.org-jetbrains:uast:26.1.3:uast-26.1.3.jar:3f3f6651d0c7685a77ecb22e9c82d6b49fdf24322c17360768dc530678f43265',
+        'com.android.tools.layoutlib:layoutlib-api:26.1.3:layoutlib-api-26.1.3.jar:10bc73ce706c45629872d6a999dbe12116df64e24f47ff93b7b13121ff57b4b0',
+        'com.android.tools.lint:lint-api:26.1.3:lint-api-26.1.3.jar:6f97323f9af8deda86278717885b5c927f3766757db89709f52d11d42b6fb751',
+        'com.android.tools.lint:lint-checks:26.1.3:lint-checks-26.1.3.jar:73c3d53784c9ce3e6d5968506581918e0179645d20809927ca4a001dd766b001',
+        'com.android.tools.lint:lint-gradle-api:26.1.3:lint-gradle-api-26.1.3.jar:7ca3c4866ec21dc21d53a9d86f752b77ace6f6c610a0c9dc877313856c733d9d',
+        'com.android.tools.lint:lint-gradle:26.1.3:lint-gradle-26.1.3.jar:db0c354b8f4b6f6637e31f91c564785a59ff896325331fcbc3de7458e0b6c067',
+        'com.android.tools.lint:lint-kotlin:26.1.3:lint-kotlin-26.1.3.jar:94e2b0f4565a241561cfb8fc1222bb3f132a3b98d2a90421dbb72ee8358e7d68',
+        'com.android.tools.lint:lint:26.1.3:lint-26.1.3.jar:8d5f32c989c6d191d712e90ad3ca2d1c409313599551d04d834caa44d26c78df',
+        'com.android.tools:annotations:26.1.3:annotations-26.1.3.jar:c950430b24ac5d58fc97e7283b8f0115f99587e76e08b4e1e2aaa780f2d77323',
+        'com.android.tools:common:26.1.3:common-26.1.3.jar:7c31a90581a148ab219f615a59667f0dded7fa39b248529784474da3c2274ef2',
+        'com.android.tools:dvlib:26.1.3:dvlib-26.1.3.jar:0cae87906f53d3f1088366a916ed180a7312b6d9919b90797f238875c8492855',
+        'com.android.tools:repository:26.1.3:repository-26.1.3.jar:52d4539cc68db91b261e2a33b2c8206b26e05539078758dc28cfb3854adb4f59',
+        'com.android.tools:sdk-common:26.1.3:sdk-common-26.1.3.jar:1948603ca9ff22c7ebb3178000bffa3a9dd2ca1cc5cb0c793cae08468b8fcfc1',
+        'com.android.tools:sdklib:26.1.3:sdklib-26.1.3.jar:4adcfaad9514607098d2c51503c39811112d3050f4d1e744c01c7f08f591032b',
         'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
-        'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.code.gson:gson:2.8.0:gson-2.8.0.jar:c6221763bd79c4f1c3dc7f750b5f29a0bb38b367b81314c4f71896e340c40825',
-        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
-        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
-        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
-        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
-        'com.google.errorprone:error_prone_annotations:2.1.3: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.code.gson:gson:2.7:gson-2.7.jar:2d43eb5ea9e133d2ee2405cc14f5ee08951b8361302fdd93494a3a997b508d32',
+        'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
+        'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
+        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
+        'com.google.errorprone:error_prone_annotations:2.0.18:error_prone_annotations-2.0.18.jar:cb4cfad870bf563a07199f3ebea5763f0dec440fcda0b318640b1feaa788656b',
+        'com.google.guava:guava:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
+        'com.google.guava:guava:22.0:guava-22.0.jar:1158e94c7de4da480873f0b4ab4a1da14c0d23d4b1902cc94a58a6f0f9ab579e',
         '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',
-        'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
         'com.squareup:javawriter:2.5.0:javawriter-2.5.0.jar:fcfb09fb0ea0aa97d3cfe7ea792398081348e468f126b3603cb3803f240197f0',
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
         'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
         'com.sun.xml.fastinfoset:FastInfoset:1.2.13:FastInfoset-1.2.13.jar:27a77db909f3c2833c0b1a37c55af1db06045118ad2eed96ce567b6632bce038',
-        'commons-codec:commons-codec:1.9:commons-codec-1.9.jar:ad19d2601c3abf0b946b5c3a4113e226a8c1e3305e395b90013b78dd94a723ce',
-        'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
+        'commons-codec:commons-codec:1.6:commons-codec-1.6.jar:54b34e941b8e1414bd3e40d736efd3481772dc26db3296f6aa45cec9f6203d86',
+        'commons-logging:commons-logging:1.1.1:commons-logging-1.1.1.jar:ce6f913cad1f0db3aad70186d65c5bc7ffcc9a99e3fe8e0b137312819f7c362f',
         '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',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
@@ -61,28 +55,24 @@ dependencyVerification {
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.apache.commons:commons-compress:1.12:commons-compress-1.12.jar:2c1542faf343185b7cab9c3d55c8ae5471d6d095d3887a4adefdbdf2984dc0b6',
-        'org.apache.httpcomponents:httpclient:4.5.2:httpclient-4.5.2.jar:0dffc621400d6c632f55787d996b8aeca36b30746a716e079a985f24d8074057',
-        'org.apache.httpcomponents:httpcore:4.4.5:httpcore-4.4.5.jar:64d5453874cab7e40a7065cb01a9a9ca1053845a9786b478878b679e0580cec3',
-        'org.apache.httpcomponents:httpmime:4.5.2:httpmime-4.5.2.jar:231a3f7e4962053db2be8461d5422e68fc458a3a7dd7d8ada803a348e21f8f07',
+        'org.apache.httpcomponents:httpclient:4.2.6:httpclient-4.2.6.jar:362e9324ee7c697e21279e20077b52737ddef3f1b2c1a7abe5ad34b465145550',
+        'org.apache.httpcomponents:httpcore:4.2.5:httpcore-4.2.5.jar:e5e82da4cc66c8d917bbf743e3c0752efe8522735e7fc9dbddb65bccea81cfe9',
+        'org.apache.httpcomponents:httpmime:4.1:httpmime-4.1.jar:31629566148e8a47688ae43b420abc3ecd783ed15b33bebc00824bf24c9b15aa',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.9:obfs4proxy-android-0.0.9.zip:9b7e9181535ea8d8bbe8ae6338e08cf4c5fc1e357a779393e0ce49586d459ae0',
-        'org.briarproject:tor-android:0.3.5.8:tor-android-0.3.5.8.zip:42a13a6f185be1a62f42e3f30ce66a3c099ac5ec890a65e7593111b65b44a54a',
-        'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
-        'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
-        'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
+        'org.briarproject:tor-android:0.2.9.16:tor-android-0.2.9.16.zip:515e33dda6a30853c885a2de2c79ae1ab9ad8b6db44f5db8890333ec2e24f4ae',
+        'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
         'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
         'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
         'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.21:kotlin-reflect-1.3.21.jar:a3065c822633191e0a3e3ee12a29bec234fc4b2864a6bb87ef48cce3e9e0c26a',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.21:kotlin-stdlib-common-1.3.21.jar:cea61f7b611895e64f58569a9757fc0ab0d582f107211e1930e0ce2a0add52a7',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.21:kotlin-stdlib-jdk7-1.3.21.jar:a87875604fd42140da6938ae4d35ee61081f4482536efc6d2615b8b626a198af',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.21:kotlin-stdlib-jdk8-1.3.21.jar:5823ed66ac122a1c55442ebca5a209a843ccd87f562edc31a787f3d2e47f74d4',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.21:kotlin-stdlib-1.3.21.jar:38ba2370d9f06f50433e06b2ca775b94473c2e2785f410926079ab793c72b034',
+        'org.jetbrains.kotlin:kotlin-reflect:1.2.0:kotlin-reflect-1.2.0.jar:4f48a872bad6e4d9c053f4ad610d11e4012ad7e58dc19a03dd5eb811f36069dd',
+        'org.jetbrains.kotlin:kotlin-stdlib-jre7:1.2.0:kotlin-stdlib-jre7-1.2.0.jar:c7a20fb951d437797afe8980aff6c1e5a03f310c661ba58ba1d4fa90cb0f2926',
+        'org.jetbrains.kotlin:kotlin-stdlib-jre8:1.2.0:kotlin-stdlib-jre8-1.2.0.jar:633524eee6ef1941f7cb1dab7ee3927b0a221ceee9047aeb5515f4cbb990c82a',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.2.0:kotlin-stdlib-1.2.0.jar:05cfd9f5ac0b41910703a8925f7211a495909b27a2ffdd1c5106f1689aeafcd4',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
@@ -91,11 +81,11 @@ dependencyVerification {
         'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
         'org.jvnet.staxex:stax-ex:1.7.7:stax-ex-1.7.7.jar:a31ff7d77163c0deb09e7fee59ad35ae44c2cee2cc8552a116ccd1583d813fb4',
         'org.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
-        'org.ow2.asm:asm-analysis:6.0:asm-analysis-6.0.jar:2f1a6387219c3a6cc4856481f221b03bd9f2408a326d416af09af5d6f608c1f4',
-        'org.ow2.asm:asm-commons:6.0:asm-commons-6.0.jar:f1bce5c648a96a017bdcd01fe5d59af9845297fd7b79b81c015a6fbbd9719abf',
-        'org.ow2.asm:asm-tree:6.0:asm-tree-6.0.jar:887998fb69727c8759e4d253f856822801e33f9fd4caa566b3ac58ee92106215',
-        'org.ow2.asm:asm-util:6.0:asm-util-6.0.jar:356afebdb0f870175262e5188f8709a3b17aa2a5a6a4b0340b04d4b449bca5f6',
+        'org.ow2.asm:asm-analysis:5.1:asm-analysis-5.1.jar:a34658f5c5de4b573eef21131cc32cc25f7b66407944f312b28ec2e56abb1fa9',
+        'org.ow2.asm:asm-commons:5.1:asm-commons-5.1.jar:97b3786e1f55e74bddf8ad102bf50e33bbcbc1f6b7fd7b36f0bbbb25cd4981be',
+        'org.ow2.asm:asm-tree:5.1:asm-tree-5.1.jar:c0de2bbc4cb8297419659813ecd4ed1d077ed1dd5c1f5544cc5143e493e84c10',
+        'org.ow2.asm:asm-util:5.1:asm-util-5.1.jar:ee032c39ae5e3cd099148fbba9a2124f9ed613e5cb93e03ee0fa8808ce364040',
         'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
-        'org.ow2.asm:asm:6.0:asm-6.0.jar:dd8971c74a4e697899a8e95caae4ea8760ea6c486dc6b97b1795e75760420461',
+        'org.ow2.asm:asm:5.1:asm-5.1.jar:d2da399a9967c69f0a21739256fa79d284222c223082cacadc17372244764b54',
     ]
 }

bramble-api/build.gradle

@@ -7,13 +7,15 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.19"
+	implementation "com.google.dagger:dagger:2.0.2"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	testImplementation "org.hamcrest:hamcrest-library:1.3"
+	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

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

@@ -1,26 +0,0 @@
-package org.briarproject.bramble.api;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.concurrent.Immutable;
-
-@Immutable
-@NotNullByDefault
-public class Pair<A, B> {
-
-	private final A first;
-	private final B second;
-
-	public Pair(A first, B second) {
-		this.first = first;
-		this.second = second;
-	}
-
-	public A getFirst() {
-		return first;
-	}
-
-	public B getSecond() {
-		return second;
-	}
-}

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

@@ -38,18 +38,4 @@ public abstract class StringMap extends Hashtable<String, String> {
 	public void putInt(String key, int value) {
 		put(key, String.valueOf(value));
 	}
-
-	public long getLong(String key, long defaultValue) {
-		String s = get(key);
-		if (s == null) return defaultValue;
-		try {
-			return Long.valueOf(s);
-		} catch (NumberFormatException e) {
-			return defaultValue;
-		}
-	}
-
-	public void putLong(String key, long value) {
-		put(key, String.valueOf(value));
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/battery/BatteryManager.java

@@ -1,6 +0,0 @@
-package org.briarproject.bramble.api.battery;
-
-public interface BatteryManager {
-
-	boolean isCharging();
-}

bramble-api/src/main/java/org/briarproject/bramble/api/battery/event/BatteryEvent.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.api.battery.event;
-
-import org.briarproject.bramble.api.event.Event;
-
-/**
- * An event that is broadcast when the device starts or stops charging.
- */
-public class BatteryEvent extends Event {
-
-	private final boolean charging;
-
-	public BatteryEvent(boolean charging) {
-		this.charging = charging;
-	}
-
-	public boolean isCharging() {
-		return charging;
-	}
-}

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

@@ -9,7 +9,7 @@ import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageContext;
-import org.briarproject.bramble.api.sync.validation.MessageValidator;
+import org.briarproject.bramble.api.sync.ValidationManager.MessageValidator;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.util.logging.Logger;
@@ -48,8 +48,12 @@ public abstract class BdfMessageValidator implements MessageValidator {
 			throw new InvalidMessageException(
 					"Timestamp is too far in the future");
 		}
+		byte[] body = m.getBody();
+		if (body.length == 0) {
+			throw new InvalidMessageException("Message is too short");
+		}
 		try {
-			BdfList bodyList = clientHelper.toList(m.getBody());
+			BdfList bodyList = clientHelper.toList(body);
 			BdfMessageContext result = validateMessage(m, g, bodyList);
 			Metadata meta = metadataEncoder.encode(result.getDictionary());
 			return new MessageContext(meta, result.getDependencies());

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

@@ -4,12 +4,8 @@ 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.util.StringUtils.toUtf8;
-
 @Immutable
 @NotNullByDefault
 public class Contact {
@@ -17,21 +13,13 @@ public class Contact {
 	private final ContactId id;
 	private final Author author;
 	private final AuthorId localAuthorId;
-	@Nullable
-	private final String alias;
 	private final boolean verified, active;
 
 	public Contact(ContactId id, Author author, AuthorId localAuthorId,
-			@Nullable String alias, boolean verified, boolean active) {
-		if (alias != null) {
-			int aliasLength = toUtf8(alias).length;
-			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
-				throw new IllegalArgumentException();
-		}
+			boolean verified, boolean active) {
 		this.id = id;
 		this.author = author;
 		this.localAuthorId = localAuthorId;
-		this.alias = alias;
 		this.verified = verified;
 		this.active = active;
 	}
@@ -48,11 +36,6 @@ public class Contact {
 		return localAuthorId;
 	}
 
-	@Nullable
-	public String getAlias() {
-		return alias;
-	}
-
 	public boolean isVerified() {
 		return verified;
 	}

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

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

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

@@ -41,7 +41,8 @@ public interface ContactExchangeTask {
 	/**
 	 * Exchanges contact information with a remote peer.
 	 */
-	void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
+	void startExchange(ContactExchangeListener listener,
+			LocalAuthor localAuthor, SecretKey masterSecret,
 			DuplexTransportConnection conn, TransportId transportId,
 			boolean alice);
 }

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

@@ -5,16 +5,11 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.AuthorInfo;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
 
-import javax.annotation.Nullable;
-
-import static org.briarproject.bramble.api.contact.PendingContact.PendingContactState.FAILED;
-
 @NotNullByDefault
 public interface ContactManager {
 
@@ -54,35 +49,6 @@ public interface ContactManager {
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException;
 
-	/**
-	 * Returns the static link that needs to be sent to the contact to be added.
-	 */
-	String getRemoteContactLink();
-
-	/**
-	 * Returns true if the given link is syntactically valid.
-	 */
-	boolean isValidRemoteContactLink(String link);
-
-	/**
-	 * 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.
-	 */
-	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 FAILED}.
-	 */
-	void removePendingContact(PendingContact pendingContact);
-
 	/**
 	 * Returns the contact with the given ID.
 	 */
@@ -127,18 +93,6 @@ public interface ContactManager {
 	void setContactActive(Transaction txn, ContactId c, boolean active)
 			throws DbException;
 
-	/**
-	 * 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 name for the contact or unsets it if alias is null.
-	 */
-	void setContactAlias(ContactId c, @Nullable String alias)
-			throws DbException;
-
 	/**
 	 * Return true if a contact with this name and public key already exists
 	 */
@@ -151,16 +105,6 @@ public interface ContactManager {
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
 
-	/**
-	 * Returns the {@link AuthorInfo} for the given author.
-	 */
-	AuthorInfo getAuthorInfo(AuthorId a) throws DbException;
-
-	/**
-	 * Returns the {@link AuthorInfo} for the given author.
-	 */
-	AuthorInfo getAuthorInfo(Transaction txn, AuthorId a) throws DbException;
-
 	interface ContactHook {
 
 		void addingContact(Transaction txn, Contact c) throws DbException;

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

@@ -1,54 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.concurrent.Immutable;
-
-@Immutable
-@NotNullByDefault
-public class PendingContact {
-
-	public enum PendingContactState {
-		WAITING_FOR_CONNECTION,
-		CONNECTED,
-		ADDING_CONTACT,
-		FAILED
-	}
-
-	private final PendingContactId id;
-	private final String alias;
-	private final PendingContactState state;
-	private final long timestamp;
-
-	public PendingContact(PendingContactId id, String alias,
-			PendingContactState state, long timestamp) {
-		this.id = id;
-		this.alias = alias;
-		this.state = state;
-		this.timestamp = timestamp;
-	}
-
-	public String getAlias() {
-		return alias;
-	}
-
-	public PendingContactState getState() {
-		return state;
-	}
-
-	public long getTimestamp() {
-		return timestamp;
-	}
-
-	@Override
-	public int hashCode() {
-		return id.hashCode();
-	}
-
-	@Override
-	public boolean equals(Object o) {
-		return o instanceof PendingContact &&
-				id.equals(((PendingContact) o).id);
-	}
-
-}

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

@@ -1,11 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.UniqueId;
-
-public class PendingContactId extends UniqueId {
-
-	public PendingContactId(byte[] id) {
-		super(id);
-	}
-
-}

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

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

@@ -1,20 +0,0 @@
-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/PendingContactStateChangedEvent.java

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

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

@@ -1,71 +0,0 @@
-package org.briarproject.bramble.api.data;
-
-import org.briarproject.bramble.api.Bytes;
-import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-
-import javax.annotation.Nullable;
-
-import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-
-@NotNullByDefault
-public class BdfStringUtils {
-
-	public static String toString(@Nullable Object o) throws FormatException {
-		return toString(o, 0);
-	}
-
-	private static String toString(@Nullable Object o, int indent)
-			throws FormatException {
-		if (o == null || o == NULL_VALUE) return "null";
-		if (o instanceof Boolean) return o.toString();
-		if (o instanceof Number) return o.toString();
-		if (o instanceof String) return "\"" + o + "\"";
-		if (o instanceof Bytes)
-			return "x" + toHexString(((Bytes) o).getBytes());
-		if (o instanceof byte[])
-			return "x" + toHexString((byte[]) o);
-		if (o instanceof List) {
-			List<?> list = (List) o;
-			StringBuilder sb = new StringBuilder();
-			sb.append("[\n");
-			int i = 0, size = list.size();
-			for (Object e : list) {
-				indent(sb, indent + 1);
-				sb.append(toString(e, indent + 1));
-				if (i++ < size - 1) sb.append(',');
-				sb.append('\n');
-			}
-			indent(sb, indent);
-			sb.append(']');
-			return sb.toString();
-		}
-		if (o instanceof Map) {
-			Map<?, ?> map = (Map) o;
-			StringBuilder sb = new StringBuilder();
-			sb.append("{\n");
-			int i = 0, size = map.size();
-			for (Entry e : map.entrySet()) {
-				indent(sb, indent + 1);
-				sb.append(toString(e.getKey(), indent + 1));
-				sb.append(": ");
-				sb.append(toString(e.getValue(), indent + 1));
-				if (i++ < size - 1) sb.append(',');
-				sb.append('\n');
-			}
-			indent(sb, indent);
-			sb.append('}');
-			return sb.toString();
-		}
-		throw new FormatException();
-	}
-
-	private static void indent(StringBuilder sb, int indent) {
-		for (int i = 0; i < indent; i++) sb.append('\t');
-	}
-}

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

@@ -19,7 +19,6 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
-import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -29,6 +28,8 @@ import java.util.Map;
 
 import javax.annotation.Nullable;
 
+import static org.briarproject.bramble.api.sync.ValidationManager.State;
+
 /**
  * Encapsulates the database implementation and exposes high-level operations
  * to other components.
@@ -75,27 +76,6 @@ public interface DatabaseComponent {
 	 */
 	void endTransaction(Transaction txn);
 
-	/**
-	 * Runs the given task within a transaction.
-	 */
-	<E extends Exception> void transaction(boolean readOnly,
-			DbRunnable<E> task) throws DbException, E;
-
-	/**
-	 * Runs the given task within a transaction and returns the result of the
-	 * task.
-	 */
-	<R, E extends Exception> R transactionWithResult(boolean readOnly,
-			DbCallable<R, E> task) throws DbException, E;
-
-	/**
-	 * Runs the given task within a transaction and returns the result of the
-	 * task, which may be null.
-	 */
-	@Nullable
-	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,
-			NullableDbCallable<R, E> task) throws DbException, E;
-
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
 	 * and returns an ID for the contact.
@@ -373,12 +353,12 @@ public interface DatabaseComponent {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
 	 * For missing dependencies and dependencies in other groups, the state
-	 * {@link MessageState UNKNOWN} is returned.
+	 * {@link State UNKNOWN} is returned.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, MessageState> getMessageDependencies(Transaction txn,
-			MessageId m) throws DbException;
+	Map<MessageId, State> getMessageDependencies(Transaction txn, MessageId m)
+			throws DbException;
 
 	/**
 	 * Returns the IDs and states of all dependents of the given message.
@@ -387,16 +367,15 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, MessageState> getMessageDependents(Transaction txn,
-			MessageId m) throws DbException;
+	Map<MessageId, State> getMessageDependents(Transaction txn, MessageId m)
+			throws DbException;
 
 	/**
 	 * Gets the validation and delivery state of the given message.
 	 * <p/>
 	 * Read-only.
 	 */
-	MessageState getMessageState(Transaction txn, MessageId m)
-			throws DbException;
+	State getMessageState(Transaction txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the status of the given delivered message with respect to the
@@ -523,12 +502,6 @@ public interface DatabaseComponent {
 	void setContactActive(Transaction txn, ContactId c, boolean active)
 			throws DbException;
 
-	/**
-	 * 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 the given group's visibility to the given contact.
 	 */
@@ -543,7 +516,7 @@ public interface DatabaseComponent {
 	/**
 	 * Sets the validation and delivery state of the given message.
 	 */
-	void setMessageState(Transaction txn, MessageId m, MessageState state)
+	void setMessageState(Transaction txn, MessageId m, State state)
 			throws DbException;
 
 	/**

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

@@ -1,9 +0,0 @@
-package org.briarproject.bramble.api.db;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface DbCallable<R, E extends Exception> {
-
-	R call(Transaction txn) throws DbException, E;
-}

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

@@ -1,9 +0,0 @@
-package org.briarproject.bramble.api.db;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface DbRunnable<E extends Exception> {
-
-	void run(Transaction txn) throws DbException, E;
-}

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

@@ -6,10 +6,6 @@ public interface MigrationListener {
 	 * This is called when a migration is started while opening the database.
 	 * It will be called once for each migration being applied.
 	 */
-	void onDatabaseMigration();
+	void onMigrationRun();
 
-	/**
-	 * This is called when compaction is started while opening the database.
-	 */
-	void onDatabaseCompaction();
 }

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

@@ -1,12 +0,0 @@
-package org.briarproject.bramble.api.db;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.Nullable;
-
-@NotNullByDefault
-public interface NullableDbCallable<R, E extends Exception> {
-
-	@Nullable
-	R call(Transaction txn) throws DbException, E;
-}

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

@@ -16,6 +16,10 @@ import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_K
 @NotNullByDefault
 public class Author implements Nameable {
 
+	public enum Status {
+		NONE, ANONYMOUS, UNKNOWN, UNVERIFIED, VERIFIED, OURSELVES
+	}
+
 	/**
 	 * The current version of the author structure.
 	 */

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

@@ -1,56 +0,0 @@
-package org.briarproject.bramble.api.identity;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.Immutable;
-
-@Immutable
-@NotNullByDefault
-public class AuthorInfo {
-
-	public enum Status {
-		NONE, ANONYMOUS, UNKNOWN, UNVERIFIED, VERIFIED, OURSELVES;
-
-		public boolean isContact() {
-			return this == UNVERIFIED || this == VERIFIED;
-		}
-	}
-
-	private final Status status;
-	@Nullable
-	private final String alias;
-
-	public AuthorInfo(Status status, @Nullable String alias) {
-		this.status = status;
-		this.alias = alias;
-	}
-
-	public AuthorInfo(Status status) {
-		this(status, null);
-	}
-
-	public Status getStatus() {
-		return status;
-	}
-
-	@Nullable
-	public String getAlias() {
-		return alias;
-	}
-
-	@Override
-	public int hashCode() {
-		int hashCode = status.ordinal();
-		if (alias != null) hashCode += alias.hashCode();
-		return hashCode;
-	}
-
-	@Override
-	public boolean equals(Object o) {
-		if (!(o instanceof AuthorInfo)) return false;
-		AuthorInfo info = (AuthorInfo) o;
-		return status == info.status &&
-				(alias == null ? info.alias == null : alias.equals(info.alias));
-	}
-}

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.api.identity;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.identity.Author.Status;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 @NotNullByDefault
@@ -36,4 +37,14 @@ public interface IdentityManager {
 	 */
 	LocalAuthor getLocalAuthor(Transaction txn) throws DbException;
 
+	/**
+	 * Returns the {@link Status} of the given author.
+	 */
+	Status getAuthorStatus(AuthorId a) throws DbException;
+
+	/**
+	 * Returns the {@link Status} of the given author.
+	 */
+	Status getAuthorStatus(Transaction txn, AuthorId a) throws DbException;
+
 }

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

@@ -21,7 +21,7 @@ public interface KeyAgreementConstants {
 	/**
 	 * The connection timeout in milliseconds.
 	 */
-	long CONNECTION_TIMEOUT = 60_000;
+	long CONNECTION_TIMEOUT = 20 * 1000;
 
 	/**
 	 * The transport identifier for Bluetooth.

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

@@ -34,8 +34,7 @@ public interface LifecycleManager {
 	 */
 	enum LifecycleState {
 
-		STARTING, MIGRATING_DATABASE, COMPACTING_DATABASE, STARTING_SERVICES,
-		RUNNING, STOPPING;
+		STARTING, MIGRATING_DATABASE, STARTING_SERVICES, RUNNING, STOPPING;
 
 		public boolean isAfter(LifecycleState state) {
 			return ordinal() > state.ordinal();

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

@@ -1,15 +0,0 @@
-package org.briarproject.bramble.api.nullsafety;
-
-import javax.annotation.Nullable;
-
-@NotNullByDefault
-public class NullSafety {
-
-	/**
-	 * Stand-in for `Objects.requireNonNull()`.
-	 */
-	public static <T> T requireNonNull(@Nullable T t) {
-		if (t == null) throw new NullPointerException();
-		return t;
-	}
-}

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

@@ -4,8 +4,7 @@ public interface TorConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.tor");
 
-	String PROP_ONION_V2 = "onion";
-	String PROP_ONION_V3 = "onion3";
+	String PROP_ONION = "onion";
 
 	int SOCKS_PORT = 59050;
 	int CONTROL_PORT = 59051;
@@ -16,7 +15,6 @@ public interface TorConstants {
 	String PREF_TOR_NETWORK = "network2";
 	String PREF_TOR_PORT = "port";
 	String PREF_TOR_MOBILE = "useMobileData";
-	String PREF_TOR_ONLY_WHEN_CHARGING = "onlyWhenCharging";
 
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;
 	int PREF_TOR_NETWORK_WITHOUT_BRIDGES = 1;

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

@@ -16,7 +16,6 @@ public class Message {
 	private final byte[] body;
 
 	public Message(MessageId id, GroupId groupId, long timestamp, byte[] body) {
-		if (body.length == 0) throw new IllegalArgumentException();
 		if (body.length > MAX_MESSAGE_BODY_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;

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

@@ -0,0 +1,87 @@
+package org.briarproject.bramble.api.sync;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+/**
+ * Responsible for managing message validators and passing them messages to
+ * validate.
+ */
+@NotNullByDefault
+public interface ValidationManager {
+
+	enum State {
+
+		UNKNOWN(0), INVALID(1), PENDING(2), DELIVERED(3);
+
+		private final int value;
+
+		State(int value) {
+			this.value = value;
+		}
+
+		public int getValue() {
+			return value;
+		}
+
+		public static State fromValue(int value) {
+			for (State s : values()) if (s.value == value) return s;
+			throw new IllegalArgumentException();
+		}
+	}
+
+	/**
+	 * Registers the message validator for the given client. This method
+	 * should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerMessageValidator(ClientId c, int majorVersion,
+			MessageValidator v);
+
+	/**
+	 * Registers the incoming message hook for the given client. The hook will
+	 * be called once for each incoming message that passes validation. This
+	 * method should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerIncomingMessageHook(ClientId c, int majorVersion,
+			IncomingMessageHook hook);
+
+	interface MessageValidator {
+
+		/**
+		 * Validates the given message and returns its metadata and
+		 * dependencies.
+		 */
+		MessageContext validateMessage(Message m, Group g)
+				throws InvalidMessageException;
+	}
+
+	interface IncomingMessageHook {
+
+		/**
+		 * Called once for each incoming message that passes validation.
+		 *
+		 * @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,
+		 * the message will be permanently invalidated.
+		 * @throws InvalidMessageException for any non-database error
+		 * that occurs while handling remotely created data.
+		 * This includes errors that occur while handling locally created data
+		 * in a context controlled by remotely created data
+		 * (for example, parsing the metadata of a dependency
+		 * of an incoming message).
+		 * Throwing this will delete the incoming message and its metadata
+		 * marking it as invalid in the database.
+		 * Never rethrow DbException as InvalidMessageException!
+		 */
+		boolean incomingMessage(Transaction txn, Message m, Metadata meta)
+				throws DbException, InvalidMessageException;
+	}
+}

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

@@ -3,10 +3,11 @@ package org.briarproject.bramble.api.sync.event;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.validation.MessageState;
 
 import javax.annotation.concurrent.Immutable;
 
+import static org.briarproject.bramble.api.sync.ValidationManager.State;
+
 /**
  * An event that is broadcast when a message state changed.
  */
@@ -16,10 +17,10 @@ public class MessageStateChangedEvent extends Event {
 
 	private final MessageId messageId;
 	private final boolean local;
-	private final MessageState state;
+	private final State state;
 
 	public MessageStateChangedEvent(MessageId messageId, boolean local,
-			MessageState state) {
+			State state) {
 		this.messageId = messageId;
 		this.local = local;
 		this.state = state;
@@ -33,7 +34,7 @@ public class MessageStateChangedEvent extends Event {
 		return local;
 	}
 
-	public MessageState getState() {
+	public State getState() {
 		return state;
 	}
 

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

@@ -1,31 +0,0 @@
-package org.briarproject.bramble.api.sync.validation;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Metadata;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.sync.InvalidMessageException;
-import org.briarproject.bramble.api.sync.Message;
-
-public interface IncomingMessageHook {
-
-	/**
-	 * Called once for each incoming message that passes validation.
-	 *
-	 * @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,
-	 * the message will be permanently invalidated.
-	 * @throws InvalidMessageException for any non-database error
-	 * that occurs while handling remotely created data.
-	 * This includes errors that occur while handling locally created data
-	 * in a context controlled by remotely created data
-	 * (for example, parsing the metadata of a dependency
-	 * of an incoming message).
-	 * Throwing this will delete the incoming message and its metadata
-	 * marking it as invalid in the database.
-	 * Never rethrow DbException as InvalidMessageException!
-	 */
-	boolean incomingMessage(Transaction txn, Message m, Metadata meta)
-			throws DbException, InvalidMessageException;
-}

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

@@ -1,21 +0,0 @@
-package org.briarproject.bramble.api.sync.validation;
-
-public enum MessageState {
-
-	UNKNOWN(0), INVALID(1), PENDING(2), DELIVERED(3);
-
-	private final int value;
-
-	MessageState(int value) {
-		this.value = value;
-	}
-
-	public int getValue() {
-		return value;
-	}
-
-	public static MessageState fromValue(int value) {
-		for (MessageState s : values()) if (s.value == value) return s;
-		throw new IllegalArgumentException();
-	}
-}

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

@@ -1,16 +0,0 @@
-package org.briarproject.bramble.api.sync.validation;
-
-import org.briarproject.bramble.api.sync.Group;
-import org.briarproject.bramble.api.sync.InvalidMessageException;
-import org.briarproject.bramble.api.sync.Message;
-import org.briarproject.bramble.api.sync.MessageContext;
-
-public interface MessageValidator {
-
-	/**
-	 * Validates the given message and returns its metadata and
-	 * dependencies.
-	 */
-	MessageContext validateMessage(Message m, Group g)
-			throws InvalidMessageException;
-}

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

@@ -1,31 +0,0 @@
-package org.briarproject.bramble.api.sync.validation;
-
-import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.ClientId;
-
-/**
- * Responsible for managing message validators and passing them messages to
- * validate.
- */
-@NotNullByDefault
-public interface ValidationManager {
-
-	/**
-	 * Registers the {@link MessageValidator} for the given client. This method
-	 * should be called before
-	 * {@link LifecycleManager#startServices(SecretKey)}.
-	 */
-	void registerMessageValidator(ClientId c, int majorVersion,
-			MessageValidator v);
-
-	/**
-	 * Registers the {@link IncomingMessageHook} for the given client. The hook
-	 * will be called once for each incoming message that passes validation.
-	 * This method should be called before
-	 * {@link LifecycleManager#startServices(SecretKey)}.
-	 */
-	void registerIncomingMessageHook(ClientId c, int majorVersion,
-			IncomingMessageHook hook);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/versioning/ClientVersioningManager.java

@@ -38,13 +38,6 @@ public interface ClientVersioningManager {
 	Visibility getClientVisibility(Transaction txn, ContactId contactId,
 			ClientId clientId, int majorVersion) throws DbException;
 
-	/**
-	 * Returns the minor version of the given client that is supported by the
-	 * given contact, or -1 if the contact does not support the client.
-	 */
-	int getClientMinorVersion(Transaction txn, ContactId contactId,
-			ClientId clientId, int majorVersion) throws DbException;
-
 	interface ClientVersioningHook {
 
 		void onClientVisibilityChanging(Transaction txn, Contact c,

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

@@ -8,15 +8,12 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.net.ServerSocket;
 import java.net.Socket;
-import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 public class IoUtils {
@@ -57,35 +54,16 @@ public class IoUtils {
 			out.flush();
 			out.close();
 		} catch (IOException e) {
-			tryToClose(in, LOG, WARNING);
-			tryToClose(out, LOG, WARNING);
+			tryToClose(in);
+			tryToClose(out);
 		}
 	}
 
-	public static void tryToClose(@Nullable Closeable c, Logger logger,
-			Level level) {
+	private static void tryToClose(@Nullable Closeable c) {
 		try {
 			if (c != null) c.close();
 		} catch (IOException e) {
-			logException(logger, level, e);
-		}
-	}
-
-	public static void tryToClose(@Nullable Socket s, Logger logger,
-			Level level) {
-		try {
-			if (s != null) s.close();
-		} catch (IOException e) {
-			logException(logger, level, e);
-		}
-	}
-
-	public static void tryToClose(@Nullable ServerSocket ss, Logger logger,
-			Level level) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			logException(logger, level, e);
+			// We did our best
 		}
 	}
 

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

@@ -10,6 +10,8 @@ public class OsUtils {
 	@Nullable
 	private static final String os = System.getProperty("os.name");
 	@Nullable
+	private static final String version = System.getProperty("os.version");
+	@Nullable
 	private static final String vendor = System.getProperty("java.vendor");
 
 	public static boolean isWindows() {

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

@@ -47,7 +47,7 @@ public class StringUtils {
 		try {
 			return s.getBytes("UTF-8");
 		} catch (UnsupportedEncodingException e) {
-			throw new AssertionError(e);
+			throw new RuntimeException(e);
 		}
 	}
 
@@ -63,7 +63,7 @@ public class StringUtils {
 		try {
 			return decoder.decode(buffer).toString();
 		} catch (CharacterCodingException e) {
-			throw new AssertionError(e);
+			throw new RuntimeException(e);
 		}
 	}
 
@@ -153,4 +153,15 @@ public class StringUtils {
 		return new String(c);
 	}
 
+
+	public static String getRandomBase32String(int length) {
+		char[] c = new char[length];
+		for (int i = 0; i < length; i++) {
+			int character = random.nextInt(32);
+			if (character < 26) c[i] = (char) ('A' + character);
+			else c[i] = (char) ('2' + (character - 26));
+		}
+		return new String(c);
+	}
+
 }

bramble-api/src/test/java/org/briarproject/bramble/api/identity/AuthorInfoTest.java

@@ -1,42 +0,0 @@
-package org.briarproject.bramble.api.identity;
-
-import org.briarproject.bramble.test.BrambleTestCase;
-import org.junit.Test;
-
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.NONE;
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.VERIFIED;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotEquals;
-
-public class AuthorInfoTest extends BrambleTestCase {
-
-	@Test
-	public void testEquals() {
-		assertEquals(
-				new AuthorInfo(NONE),
-				new AuthorInfo(NONE, null)
-		);
-		assertEquals(
-				new AuthorInfo(NONE, "test"),
-				new AuthorInfo(NONE, "test")
-		);
-
-		assertNotEquals(
-				new AuthorInfo(NONE),
-				new AuthorInfo(VERIFIED)
-		);
-		assertNotEquals(
-				new AuthorInfo(NONE, "test"),
-				new AuthorInfo(NONE)
-		);
-		assertNotEquals(
-				new AuthorInfo(NONE),
-				new AuthorInfo(NONE, "test")
-		);
-		assertNotEquals(
-				new AuthorInfo(NONE, "a"),
-				new AuthorInfo(NONE, "b")
-		);
-	}
-
-}

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

@@ -1,24 +0,0 @@
-package org.briarproject.bramble.test;
-
-import org.briarproject.bramble.api.system.Clock;
-
-import java.util.concurrent.atomic.AtomicLong;
-
-public class SettableClock implements Clock {
-
-	private final AtomicLong time;
-
-	public SettableClock(AtomicLong time) {
-		this.time = time;
-	}
-
-	@Override
-	public long currentTimeMillis() {
-		return time.get();
-	}
-
-	@Override
-	public void sleep(long milliseconds) throws InterruptedException {
-		Thread.sleep(milliseconds);
-	}
-}

bramble-api/witness.gradle

@@ -2,7 +2,7 @@ dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
+        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',

bramble-core/build.gradle

@@ -3,10 +3,10 @@ sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
 apply plugin: 'ru.vyarus.animalsniffer'
+apply plugin: 'net.ltgt.apt'
 apply plugin: 'idea'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
-apply from: '../dagger.gradle'
 
 dependencies {
 	implementation project(path: ':bramble-api', configuration: 'default')
@@ -14,10 +14,10 @@ dependencies {
 	implementation 'com.h2database:h2:1.4.192' // The last version that supports Java 1.6
 	implementation 'org.bitlet:weupnp:0.1.4'
 	implementation 'net.i2p.crypto:eddsa:0.2.0'
-	implementation 'org.whispersystems:curve25519-java:0.5.0'
+	implementation 'org.whispersystems:curve25519-java:0.4.1'
 	implementation 'org.briarproject:jtorctl:0.3'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	apt 'com.google.dagger:dagger-compiler:2.0.2'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation 'org.hsqldb:hsqldb:2.3.5' // The last version that supports Java 1.6
@@ -25,8 +25,10 @@ dependencies {
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	testImplementation "org.hamcrest:hamcrest-library:1.3"
+	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
-	testAnnotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	testApt 'com.google.dagger:dagger-compiler:2.0.2'
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreEagerSingletons.java

@@ -8,7 +8,7 @@ import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.reporting.ReportingModule;
-import org.briarproject.bramble.sync.validation.ValidationModule;
+import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
@@ -31,11 +31,11 @@ public interface BrambleCoreEagerSingletons {
 
 	void inject(ReportingModule.EagerSingletons init);
 
+	void inject(SyncModule.EagerSingletons init);
+
 	void inject(SystemModule.EagerSingletons init);
 
 	void inject(TransportModule.EagerSingletons init);
 
-	void inject(ValidationModule.EagerSingletons init);
-
 	void inject(VersioningModule.EagerSingletons init);
 }

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java

@@ -19,7 +19,6 @@ import org.briarproject.bramble.reporting.ReportingModule;
 import org.briarproject.bramble.settings.SettingsModule;
 import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.sync.SyncModule;
-import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
@@ -48,7 +47,6 @@ import dagger.Module;
 		SyncModule.class,
 		SystemModule.class,
 		TransportModule.class,
-		ValidationModule.class,
 		VersioningModule.class
 })
 public class BrambleCoreModule {
@@ -62,9 +60,9 @@ public class BrambleCoreModule {
 		c.inject(new PluginModule.EagerSingletons());
 		c.inject(new PropertiesModule.EagerSingletons());
 		c.inject(new ReportingModule.EagerSingletons());
+		c.inject(new SyncModule.EagerSingletons());
 		c.inject(new SystemModule.EagerSingletons());
 		c.inject(new TransportModule.EagerSingletons());
-		c.inject(new ValidationModule.EagerSingletons());
 		c.inject(new VersioningModule.EagerSingletons());
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/account/AccountManagerImpl.java

@@ -159,8 +159,7 @@ class AccountManagerImpl implements AccountManager {
 	@Override
 	public boolean createAccount(String name, String password) {
 		synchronized (stateChangeLock) {
-			if (hasDatabaseKey())
-				throw new AssertionError("Already have a database key");
+			// TODO don't allow creating another account if one already exists
 			LocalAuthor localAuthor = identityManager.createLocalAuthor(name);
 			identityManager.registerLocalAuthor(localAuthor);
 			SecretKey key = crypto.generateSecretKey();
@@ -183,7 +182,6 @@ class AccountManagerImpl implements AccountManager {
 			LOG.info("Deleting account");
 			IoUtils.deleteFileOrDir(databaseConfig.getDatabaseKeyDirectory());
 			IoUtils.deleteFileOrDir(databaseConfig.getDatabaseDirectory());
-			databaseKey = null;
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/battery/DefaultBatteryManagerModule.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.battery;
-
-import org.briarproject.bramble.api.battery.BatteryManager;
-
-import dagger.Module;
-import dagger.Provides;
-
-/**
- * Provides a default implementation of {@link BatteryManager} for systems
- * without batteries.
- */
-@Module
-public class DefaultBatteryManagerModule {
-
-	@Provides
-	BatteryManager provideBatteryManager() {
-		return () -> false;
-	}
-}

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

@@ -82,7 +82,13 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void addLocalMessage(Message m, BdfDictionary metadata,
 			boolean shared) throws DbException, FormatException {
-		db.transaction(false, txn -> addLocalMessage(txn, m, metadata, shared));
+		Transaction txn = db.startTransaction(false);
+		try {
+			addLocalMessage(txn, m, metadata, shared);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override
@@ -107,7 +113,15 @@ class ClientHelperImpl implements ClientHelper {
 
 	@Override
 	public Message getMessage(MessageId m) throws DbException {
-		return db.transactionWithResult(true, txn -> getMessage(txn, m));
+		Message message;
+		Transaction txn = db.startTransaction(true);
+		try {
+			message = getMessage(txn, m);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return message;
 	}
 
 	@Override
@@ -118,7 +132,15 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfList getMessageAsList(MessageId m) throws DbException,
 			FormatException {
-		return db.transactionWithResult(true, txn -> getMessageAsList(txn, m));
+		BdfList list;
+		Transaction txn = db.startTransaction(true);
+		try {
+			list = getMessageAsList(txn, m);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return list;
 	}
 
 	@Override
@@ -130,8 +152,15 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfDictionary getGroupMetadataAsDictionary(GroupId g)
 			throws DbException, FormatException {
-		return db.transactionWithResult(true, txn ->
-				getGroupMetadataAsDictionary(txn, g));
+		BdfDictionary dictionary;
+		Transaction txn = db.startTransaction(true);
+		try {
+			dictionary = getGroupMetadataAsDictionary(txn, g);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return dictionary;
 	}
 
 	@Override
@@ -144,8 +173,15 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfDictionary getMessageMetadataAsDictionary(MessageId m)
 			throws DbException, FormatException {
-		return db.transactionWithResult(true, txn ->
-				getMessageMetadataAsDictionary(txn, m));
+		BdfDictionary dictionary;
+		Transaction txn = db.startTransaction(true);
+		try {
+			dictionary = getMessageMetadataAsDictionary(txn, m);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return dictionary;
 	}
 
 	@Override
@@ -158,8 +194,15 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
 			GroupId g) throws DbException, FormatException {
-		return db.transactionWithResult(true, txn ->
-				getMessageMetadataAsDictionary(txn, g));
+		Map<MessageId, BdfDictionary> map;
+		Transaction txn = db.startTransaction(true);
+		try {
+			map = getMessageMetadataAsDictionary(txn, g);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return map;
 	}
 
 	@Override
@@ -176,8 +219,15 @@ class ClientHelperImpl implements ClientHelper {
 	public Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
 			GroupId g, BdfDictionary query) throws DbException,
 			FormatException {
-		return db.transactionWithResult(true, txn ->
-				getMessageMetadataAsDictionary(txn, g, query));
+		Map<MessageId, BdfDictionary> map;
+		Transaction txn = db.startTransaction(true);
+		try {
+			map = getMessageMetadataAsDictionary(txn, g, query);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return map;
 	}
 
 	@Override
@@ -195,7 +245,13 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void mergeGroupMetadata(GroupId g, BdfDictionary metadata)
 			throws DbException, FormatException {
-		db.transaction(false, txn -> mergeGroupMetadata(txn, g, metadata));
+		Transaction txn = db.startTransaction(false);
+		try {
+			mergeGroupMetadata(txn, g, metadata);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override
@@ -207,7 +263,13 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void mergeMessageMetadata(MessageId m, BdfDictionary metadata)
 			throws DbException, FormatException {
-		db.transaction(false, txn -> mergeMessageMetadata(txn, m, metadata));
+		Transaction txn = db.startTransaction(false);
+		try {
+			mergeMessageMetadata(txn, m, metadata);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override

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

@@ -2,11 +2,10 @@ package org.briarproject.bramble.contact;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.contact.ContactExchangeListener;
 import org.briarproject.bramble.api.contact.ContactExchangeTask;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.contact.event.ContactExchangeFailedEvent;
-import org.briarproject.bramble.api.contact.event.ContactExchangeSucceededEvent;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -14,7 +13,7 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -65,7 +64,6 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private final ClientHelper clientHelper;
 	private final RecordReaderFactory recordReaderFactory;
 	private final RecordWriterFactory recordWriterFactory;
-	private final EventBus eventBus;
 	private final Clock clock;
 	private final ConnectionManager connectionManager;
 	private final ContactManager contactManager;
@@ -74,6 +72,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private final StreamReaderFactory streamReaderFactory;
 	private final StreamWriterFactory streamWriterFactory;
 
+	private volatile ContactExchangeListener listener;
 	private volatile LocalAuthor localAuthor;
 	private volatile DuplexTransportConnection conn;
 	private volatile TransportId transportId;
@@ -83,9 +82,8 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	@Inject
 	ContactExchangeTaskImpl(DatabaseComponent db, ClientHelper clientHelper,
 			RecordReaderFactory recordReaderFactory,
-			RecordWriterFactory recordWriterFactory, EventBus eventBus,
-			Clock clock, ConnectionManager connectionManager,
-			ContactManager contactManager,
+			RecordWriterFactory recordWriterFactory, Clock clock,
+			ConnectionManager connectionManager, ContactManager contactManager,
 			TransportPropertyManager transportPropertyManager,
 			CryptoComponent crypto, StreamReaderFactory streamReaderFactory,
 			StreamWriterFactory streamWriterFactory) {
@@ -93,7 +91,6 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		this.clientHelper = clientHelper;
 		this.recordReaderFactory = recordReaderFactory;
 		this.recordWriterFactory = recordWriterFactory;
-		this.eventBus = eventBus;
 		this.clock = clock;
 		this.connectionManager = connectionManager;
 		this.contactManager = contactManager;
@@ -104,9 +101,11 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	}
 
 	@Override
-	public void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
+	public void startExchange(ContactExchangeListener listener,
+			LocalAuthor localAuthor, SecretKey masterSecret,
 			DuplexTransportConnection conn, TransportId transportId,
 			boolean alice) {
+		this.listener = listener;
 		this.localAuthor = localAuthor;
 		this.conn = conn;
 		this.transportId = transportId;
@@ -125,8 +124,8 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			out = conn.getWriter().getOutputStream();
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);
+			listener.contactExchangeFailed();
 			tryToClose(conn);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
 			return;
 		}
 
@@ -136,7 +135,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			localProperties = transportPropertyManager.getLocalProperties();
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
+			listener.contactExchangeFailed();
 			tryToClose(conn);
 			return;
 		}
@@ -159,8 +158,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 				streamWriterFactory.createContactExchangeStreamWriter(out,
 						alice ? aliceHeaderKey : bobHeaderKey);
 		RecordWriter recordWriter =
-				recordWriterFactory
-						.createRecordWriter(streamWriter.getOutputStream());
+				recordWriterFactory.createRecordWriter(streamWriter.getOutputStream());
 
 		// Derive the nonces to be signed
 		byte[] aliceNonce = crypto.mac(ALICE_NONCE_LABEL, masterSecret,
@@ -198,7 +196,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			}
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
+			listener.contactExchangeFailed();
 			tryToClose(conn);
 			return;
 		}
@@ -206,7 +204,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		// Verify the contact's signature
 		if (!verify(remoteInfo.author, remoteNonce, remoteInfo.signature)) {
 			LOG.warning("Invalid signature");
-			eventBus.broadcast(new ContactExchangeFailedEvent());
+			listener.contactExchangeFailed();
 			tryToClose(conn);
 			return;
 		}
@@ -223,17 +221,15 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 					conn);
 			// Pseudonym exchange succeeded
 			LOG.info("Pseudonym exchange succeeded");
-			eventBus.broadcast(
-					new ContactExchangeSucceededEvent(remoteInfo.author));
+			listener.contactExchangeSucceeded(remoteInfo.author);
 		} catch (ContactExistsException e) {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);
-			eventBus.broadcast(
-					new ContactExchangeFailedEvent(remoteInfo.author));
+			listener.duplicateContact(remoteInfo.author);
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
+			listener.contactExchangeFailed();
 		}
 	}
 
@@ -291,14 +287,19 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private ContactId addContact(Author remoteAuthor, long timestamp,
 			Map<TransportId, TransportProperties> remoteProperties)
 			throws DbException {
-		return db.transactionWithResult(false, txn -> {
-			ContactId contactId = contactManager.addContact(txn, remoteAuthor,
+		ContactId contactId;
+		Transaction txn = db.startTransaction(false);
+		try {
+			contactId = contactManager.addContact(txn, remoteAuthor,
 					localAuthor.getId(), masterSecret, timestamp, alice,
 					true, true);
 			transportPropertyManager.addRemoteProperties(txn, contactId,
 					remoteProperties);
-			return contactId;
-		});
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return contactId;
 	}
 
 	private void tryToClose(DuplexTransportConnection conn) {

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

@@ -3,8 +3,6 @@ package org.briarproject.bramble.contact;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.contact.PendingContact;
-import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
@@ -12,53 +10,29 @@ 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;
-import org.briarproject.bramble.api.identity.AuthorInfo;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.transport.KeyManager;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
-import java.util.Random;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.regex.Pattern;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
-import static java.util.Collections.emptyList;
-import static org.briarproject.bramble.api.contact.PendingContact.PendingContactState.WAITING_FOR_CONNECTION;
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.OURSELVES;
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.UNKNOWN;
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.UNVERIFIED;
-import static org.briarproject.bramble.api.identity.AuthorInfo.Status.VERIFIED;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
-
 @ThreadSafe
 @NotNullByDefault
 class ContactManagerImpl implements ContactManager {
 
-	private static final int LINK_LENGTH = 64;
-	private static final String REMOTE_CONTACT_LINK =
-			"briar://" + getRandomBase32String(LINK_LENGTH);
-	private static final Pattern LINK_REGEX =
-			Pattern.compile("(briar://)?([a-z2-7]{" + LINK_LENGTH + "})");
-
 	private final DatabaseComponent db;
 	private final KeyManager keyManager;
-	private final IdentityManager identityManager;
 	private final List<ContactHook> hooks;
 
 	@Inject
-	ContactManagerImpl(DatabaseComponent db, KeyManager keyManager,
-			IdentityManager identityManager) {
+	ContactManagerImpl(DatabaseComponent db, KeyManager keyManager) {
 		this.db = db;
 		this.keyManager = keyManager;
-		this.identityManager = identityManager;
 		hooks = new CopyOnWriteArrayList<>();
 	}
 
@@ -91,63 +65,42 @@ class ContactManagerImpl implements ContactManager {
 	public ContactId addContact(Author remote, AuthorId local, SecretKey master,
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException {
-		return db.transactionWithResult(false, txn ->
-				addContact(txn, remote, local, master, timestamp, alice,
-						verified, active));
-	}
-
-	@Override
-	public String getRemoteContactLink() {
-		// TODO replace with real implementation
-		return REMOTE_CONTACT_LINK;
-	}
-
-	@SuppressWarnings("SameParameterValue")
-	private static String getRandomBase32String(int length) {
-		Random random = new Random();
-		char[] c = new char[length];
-		for (int i = 0; i < length; i++) {
-			int character = random.nextInt(32);
-			if (character < 26) c[i] = (char) ('a' + character);
-			else c[i] = (char) ('2' + (character - 26));
+		ContactId c;
+		Transaction txn = db.startTransaction(false);
+		try {
+			c = addContact(txn, remote, local, master, timestamp, alice,
+					verified, active);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
 		}
-		return new String(c);
-	}
-
-	@Override
-	public boolean isValidRemoteContactLink(String link) {
-		return LINK_REGEX.matcher(link).matches();
-	}
-
-	@Override
-	public PendingContact addRemoteContactRequest(String link, String alias) {
-		// TODO replace with real implementation
-		PendingContactId id = new PendingContactId(link.getBytes());
-		return new PendingContact(id, alias, WAITING_FOR_CONNECTION,
-				System.currentTimeMillis());
-	}
-
-	@Override
-	public Collection<PendingContact> getPendingContacts() {
-		// TODO replace with real implementation
-		return emptyList();
-	}
-
-	@Override
-	public void removePendingContact(PendingContact pendingContact) {
-		// TODO replace with real implementation
+		return c;
 	}
 
 	@Override
 	public Contact getContact(ContactId c) throws DbException {
-		return db.transactionWithResult(true, txn -> db.getContact(txn, c));
+		Contact contact;
+		Transaction txn = db.startTransaction(true);
+		try {
+			contact = db.getContact(txn, c);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return contact;
 	}
 
 	@Override
 	public Contact getContact(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException {
-		return db.transactionWithResult(true, txn ->
-				getContact(txn, remoteAuthorId, localAuthorId));
+		Transaction txn = db.startTransaction(true);
+		try {
+			Contact c = getContact(txn, remoteAuthorId, localAuthorId);
+			db.commitTransaction(txn);
+			return c;
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override
@@ -165,8 +118,14 @@ class ContactManagerImpl implements ContactManager {
 
 	@Override
 	public Collection<Contact> getActiveContacts() throws DbException {
-		Collection<Contact> contacts =
-				db.transactionWithResult(true, db::getContacts);
+		Collection<Contact> contacts;
+		Transaction txn = db.startTransaction(true);
+		try {
+			contacts = db.getContacts(txn);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 		List<Contact> active = new ArrayList<>(contacts.size());
 		for (Contact c : contacts) if (c.isActive()) active.add(c);
 		return active;
@@ -174,7 +133,13 @@ class ContactManagerImpl implements ContactManager {
 
 	@Override
 	public void removeContact(ContactId c) throws DbException {
-		db.transaction(false, txn -> removeContact(txn, c));
+		Transaction txn = db.startTransaction(false);
+		try {
+			removeContact(txn, c);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override
@@ -183,23 +148,6 @@ class ContactManagerImpl implements ContactManager {
 		db.setContactActive(txn, c, active);
 	}
 
-	@Override
-	public void setContactAlias(Transaction txn, ContactId c,
-			@Nullable String alias) throws DbException {
-		if (alias != null) {
-			int aliasLength = toUtf8(alias).length;
-			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
-				throw new IllegalArgumentException();
-		}
-		db.setContactAlias(txn, c, alias);
-	}
-
-	@Override
-	public void setContactAlias(ContactId c, @Nullable String alias)
-			throws DbException {
-		db.transaction(false, txn -> setContactAlias(txn, c, alias));
-	}
-
 	@Override
 	public boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException {
@@ -209,8 +157,15 @@ class ContactManagerImpl implements ContactManager {
 	@Override
 	public boolean contactExists(AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException {
-		return db.transactionWithResult(true, txn ->
-				contactExists(txn, remoteAuthorId, localAuthorId));
+		boolean exists;
+		Transaction txn = db.startTransaction(true);
+		try {
+			exists = contactExists(txn, remoteAuthorId, localAuthorId);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return exists;
 	}
 
 	@Override
@@ -221,23 +176,4 @@ class ContactManagerImpl implements ContactManager {
 		db.removeContact(txn, c);
 	}
 
-	@Override
-	public AuthorInfo getAuthorInfo(AuthorId a) throws DbException {
-		return db.transactionWithResult(true, txn -> getAuthorInfo(txn, a));
-	}
-
-	@Override
-	public AuthorInfo getAuthorInfo(Transaction txn, AuthorId authorId)
-			throws DbException {
-		LocalAuthor localAuthor = identityManager.getLocalAuthor(txn);
-		if (localAuthor.getId().equals(authorId))
-			return new AuthorInfo(OURSELVES);
-		Collection<Contact> contacts = db.getContactsByAuthorId(txn, authorId);
-		if (contacts.isEmpty()) return new AuthorInfo(UNKNOWN);
-		if (contacts.size() > 1) throw new AssertionError();
-		Contact c = contacts.iterator().next();
-		if (c.isVerified()) return new AuthorInfo(VERIFIED, c.getAlias());
-		else return new AuthorInfo(UNVERIFIED, c.getAlias());
-	}
-
 }

bramble-core/src/main/java/org/briarproject/bramble/data/BdfReaderImpl.java

@@ -29,7 +29,6 @@ import static org.briarproject.bramble.data.Types.STRING_16;
 import static org.briarproject.bramble.data.Types.STRING_32;
 import static org.briarproject.bramble.data.Types.STRING_8;
 import static org.briarproject.bramble.data.Types.TRUE;
-import static org.briarproject.bramble.util.StringUtils.fromUtf8;
 
 @NotThreadSafe
 @NotNullByDefault
@@ -254,7 +253,7 @@ class BdfReaderImpl implements BdfReader {
 		if (length < 0 || length > maxBufferSize) throw new FormatException();
 		if (length == 0) return "";
 		readIntoBuffer(length);
-		return fromUtf8(buf, 0, length);
+		return new String(buf, 0, length, "UTF-8");
 	}
 
 	private int readStringLength() throws IOException {

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

@@ -22,7 +22,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
-import org.briarproject.bramble.api.sync.validation.MessageState;
+import org.briarproject.bramble.api.sync.ValidationManager.State;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -106,7 +106,7 @@ interface Database<T> {
 	 * @param sender the contact from whom the message was received, or null
 	 * if the message was created locally.
 	 */
-	void addMessage(T txn, Message m, MessageState state, boolean shared,
+	void addMessage(T txn, Message m, State state, boolean shared,
 			@Nullable ContactId sender) throws DbException;
 
 	/**
@@ -114,7 +114,7 @@ interface Database<T> {
 	 * in the given state.
 	 */
 	void addMessageDependency(T txn, Message dependent, MessageId dependency,
-			MessageState dependentState) throws DbException;
+			State dependentState) throws DbException;
 
 	/**
 	 * Records that a message has been offered by the given contact.
@@ -310,11 +310,11 @@ interface Database<T> {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
 	 * For missing dependencies and dependencies in other groups, the state
-	 * {@link MessageState UNKNOWN} is returned.
+	 * {@link State UNKNOWN} is returned.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, MessageState> getMessageDependencies(T txn, MessageId m)
+	Map<MessageId, State> getMessageDependencies(T txn, MessageId m)
 			throws DbException;
 
 	/**
@@ -324,7 +324,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, MessageState> getMessageDependents(T txn, MessageId m)
+	Map<MessageId, State> getMessageDependents(T txn, MessageId m)
 			throws DbException;
 
 	/**
@@ -383,7 +383,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	MessageState getMessageState(T txn, MessageId m) throws DbException;
+	State getMessageState(T txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the status of all delivered messages in the given group with
@@ -616,12 +616,6 @@ interface Database<T> {
 	void setContactActive(T txn, ContactId c, boolean active)
 			throws DbException;
 
-	/**
-	 * Sets an alias name for a contact.
-	 */
-	void setContactAlias(T txn, ContactId c, @Nullable String alias)
-			throws DbException;
-
 	/**
 	 * Sets the given group's visibility to the given contact to either
 	 * {@link Visibility VISIBLE} or {@link Visibility SHARED}.
@@ -637,8 +631,7 @@ interface Database<T> {
 	/**
 	 * Sets the validation and delivery state of the given message.
 	 */
-	void setMessageState(T txn, MessageId m, MessageState state)
-			throws DbException;
+	void setMessageState(T txn, MessageId m, State state) throws DbException;
 
 	/**
 	 * Sets the reordering window for the given key set and transport in the

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

@@ -9,9 +9,7 @@ import org.briarproject.bramble.api.contact.event.ContactVerifiedEvent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
-import org.briarproject.bramble.api.db.DbCallable;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.DbRunnable;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.db.NoSuchContactException;
@@ -19,7 +17,6 @@ import org.briarproject.bramble.api.db.NoSuchGroupException;
 import org.briarproject.bramble.api.db.NoSuchLocalAuthorException;
 import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.db.NoSuchTransportException;
-import org.briarproject.bramble.api.db.NullableDbCallable;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
@@ -43,6 +40,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 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.ValidationManager.State;
 import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
@@ -54,7 +52,6 @@ import org.briarproject.bramble.api.sync.event.MessageToAckEvent;
 import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
-import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -75,8 +72,8 @@ import javax.inject.Inject;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
-import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
-import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.MAX_OFFERED_MESSAGES;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -169,45 +166,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			for (Event e : transaction.getEvents()) eventBus.broadcast(e);
 	}
 
-	@Override
-	public <E extends Exception> void transaction(boolean readOnly,
-			DbRunnable<E> task) throws DbException, E {
-		Transaction txn = startTransaction(readOnly);
-		try {
-			task.run(txn);
-			commitTransaction(txn);
-		} finally {
-			endTransaction(txn);
-		}
-	}
-
-	@Override
-	public <R, E extends Exception> R transactionWithResult(boolean readOnly,
-			DbCallable<R, E> task) throws DbException, E {
-		Transaction txn = startTransaction(readOnly);
-		try {
-			R result = task.call(txn);
-			commitTransaction(txn);
-			return result;
-		} finally {
-			endTransaction(txn);
-		}
-	}
-
-	@Override
-	public <R, E extends Exception> R transactionWithNullableResult(
-			boolean readOnly, NullableDbCallable<R, E> task)
-			throws DbException, E {
-		Transaction txn = startTransaction(readOnly);
-		try {
-			R result = task.call(txn);
-			commitTransaction(txn);
-			return result;
-		} finally {
-			endTransaction(txn);
-		}
-	}
-
 	private T unbox(Transaction transaction) {
 		if (transaction.isCommitted()) throw new IllegalStateException();
 		return txnClass.cast(transaction.unbox());
@@ -579,7 +537,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public MessageState getMessageState(Transaction transaction, MessageId m)
+	public State getMessageState(Transaction transaction, MessageId m)
 			throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
@@ -619,8 +577,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Map<MessageId, MessageState> getMessageDependencies(
-			Transaction transaction, MessageId m) throws DbException {
+	public Map<MessageId, State> getMessageDependencies(Transaction transaction,
+			MessageId m) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
@@ -628,8 +586,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Map<MessageId, MessageState> getMessageDependents(
-			Transaction transaction, MessageId m) throws DbException {
+	public Map<MessageId, State> getMessageDependents(Transaction transaction,
+			MessageId m) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
@@ -874,16 +832,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		transaction.attach(new ContactStatusChangedEvent(c, active));
 	}
 
-	@Override
-	public void setContactAlias(Transaction transaction, ContactId c,
-			@Nullable String alias) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsContact(txn, c))
-			throw new NoSuchContactException();
-		db.setContactAlias(txn, c, alias);
-	}
-
 	@Override
 	public void setGroupVisibility(Transaction transaction, ContactId c,
 			GroupId g, Visibility v) throws DbException {
@@ -918,7 +866,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void setMessageState(Transaction transaction, MessageId m,
-			MessageState state) throws DbException {
+			State state) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
@@ -935,10 +883,10 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, dependent.getId()))
 			throw new NoSuchMessageException();
-		MessageState dependentState =
-				db.getMessageState(txn, dependent.getId());
+		State dependentState = db.getMessageState(txn, dependent.getId());
 		for (MessageId dependency : dependencies) {
-			db.addMessageDependency(txn, dependent, dependency, dependentState);
+			db.addMessageDependency(txn, dependent, dependency,
+					dependentState);
 		}
 	}
 

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

@@ -2,8 +2,6 @@ package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.settings.Settings;
 
-import static java.util.concurrent.TimeUnit.DAYS;
-
 interface DatabaseConstants {
 
 	/**
@@ -25,16 +23,4 @@ interface DatabaseConstants {
 	 */
 	String SCHEMA_VERSION_KEY = "schemaVersion";
 
-	/**
-	 * The {@link Settings} key under which the time of the last database
-	 * compaction is stored.
-	 */
-	String LAST_COMPACTED_KEY = "lastCompacted";
-
-	/**
-	 * The maximum time between database compactions in milliseconds. When the
-	 * database is opened it will be compacted if more than this amount of time
-	 * has passed since the last compaction.
-	 */
-	long MAX_COMPACTION_INTERVAL_MS = DAYS.toMillis(30);
 }

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

@@ -1,34 +0,0 @@
-package org.briarproject.bramble.db;
-
-class DatabaseTypes {
-
-	private final String hashType, secretType, binaryType;
-	private final String counterType, stringType;
-
-	public DatabaseTypes(String hashType, String secretType, String binaryType,
-			String counterType, String stringType) {
-		this.hashType = hashType;
-		this.secretType = secretType;
-		this.binaryType = binaryType;
-		this.counterType = counterType;
-		this.stringType = stringType;
-	}
-
-	/**
-	 * Replaces database type placeholders in a statement with the actual types.
-	 * These placeholders are currently supported:
-	 * <li> _HASH
-	 * <li> _SECRET
-	 * <li> _BINARY
-	 * <li> _COUNTER
-	 * <li> _STRING
-	 */
-	String replaceTypes(String s) {
-		s = s.replaceAll("_HASH", hashType);
-		s = s.replaceAll("_SECRET", secretType);
-		s = s.replaceAll("_BINARY", binaryType);
-		s = s.replaceAll("_COUNTER", counterType);
-		s = s.replaceAll("_STRING", stringType);
-		return s;
-	}
-}

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

@@ -13,32 +13,22 @@ import java.io.File;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
-import java.sql.Statement;
 import java.util.Properties;
-import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
-
 /**
  * Contains all the H2-specific code for the database.
  */
 @NotNullByDefault
 class H2Database extends JdbcDatabase {
 
-	private static final Logger LOG = getLogger(H2Database.class.getName());
-
 	private static final String HASH_TYPE = "BINARY(32)";
 	private static final String SECRET_TYPE = "BINARY(32)";
 	private static final String BINARY_TYPE = "BINARY";
 	private static final String COUNTER_TYPE = "INT NOT NULL AUTO_INCREMENT";
 	private static final String STRING_TYPE = "VARCHAR";
-	private static final DatabaseTypes dbTypes = new DatabaseTypes(HASH_TYPE,
-			SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE);
 
 	private final DatabaseConfig config;
 	private final String url;
@@ -49,7 +39,8 @@ class H2Database extends JdbcDatabase {
 	@Inject
 	H2Database(DatabaseConfig config, MessageFactory messageFactory,
 			Clock clock) {
-		super(dbTypes, messageFactory, clock);
+		super(HASH_TYPE, SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE,
+				messageFactory, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();
@@ -115,22 +106,4 @@ class H2Database extends JdbcDatabase {
 	String getUrl() {
 		return url;
 	}
-
-	@Override
-	protected void compactAndClose() throws DbException {
-		Connection c = null;
-		Statement s = null;
-		try {
-			c = createConnection();
-			closeAllConnections();
-			s = c.createStatement();
-			s.execute("SHUTDOWN COMPACT");
-			s.close();
-			c.close();
-		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
 }

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

@@ -14,32 +14,22 @@ import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.sql.Statement;
-import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
-
 /**
  * Contains all the HSQLDB-specific code for the database.
  */
 @NotNullByDefault
 class HyperSqlDatabase extends JdbcDatabase {
 
-	private static final Logger LOG =
-			getLogger(HyperSqlDatabase.class.getName());
-
 	private static final String HASH_TYPE = "BINARY(32)";
 	private static final String SECRET_TYPE = "BINARY(32)";
 	private static final String BINARY_TYPE = "BINARY";
 	private static final String COUNTER_TYPE =
 			"INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY(START WITH 1)";
 	private static final String STRING_TYPE = "VARCHAR";
-	private static final DatabaseTypes dbTypes = new DatabaseTypes(HASH_TYPE,
-			SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE);
 
 	private final DatabaseConfig config;
 	private final String url;
@@ -50,7 +40,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 	@Inject
 	HyperSqlDatabase(DatabaseConfig config, MessageFactory messageFactory,
 			Clock clock) {
-		super(dbTypes, messageFactory, clock);
+		super(HASH_TYPE, SECRET_TYPE, BINARY_TYPE, COUNTER_TYPE, STRING_TYPE,
+				messageFactory, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();
@@ -70,24 +61,20 @@ class HyperSqlDatabase extends JdbcDatabase {
 
 	@Override
 	public void close() throws DbException {
-		Connection c = null;
-		Statement s = null;
 		try {
 			super.closeAllConnections();
-			c = createConnection();
-			s = c.createStatement();
+			Connection c = createConnection();
+			Statement s = c.createStatement();
 			s.executeQuery("SHUTDOWN");
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
 
 	@Override
-	public long getFreeSpace() {
+	public long getFreeSpace() throws DbException {
 		File dir = config.getDatabaseDirectory();
 		long maxSize = config.getMaxSize();
 		long free = dir.getFreeSpace();
@@ -117,22 +104,4 @@ class HyperSqlDatabase extends JdbcDatabase {
 		String hex = StringUtils.toHexString(key.getBytes());
 		return DriverManager.getConnection(url + ";crypt_key=" + hex);
 	}
-
-	@Override
-	protected void compactAndClose() throws DbException {
-		Connection c = null;
-		Statement s = null;
-		try {
-			super.closeAllConnections();
-			c = createConnection();
-			s = c.createStatement();
-			s.executeQuery("SHUTDOWN COMPACT");
-			s.close();
-			c.close();
-		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
 }

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

@@ -1,42 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.sql.Connection;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@NotNullByDefault
-class JdbcUtils {
-
-	static void tryToClose(@Nullable ResultSet rs, Logger logger, Level level) {
-		try {
-			if (rs != null) rs.close();
-		} catch (SQLException e) {
-			logException(logger, level, e);
-		}
-	}
-
-	static void tryToClose(@Nullable Statement s, Logger logger, Level level) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			logException(logger, level, e);
-		}
-	}
-
-	static void tryToClose(@Nullable Connection c, Logger logger, Level level) {
-		try {
-			if (c != null) c.close();
-		} catch (SQLException e) {
-			logException(logger, level, e);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration38_39.java

@@ -7,8 +7,10 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
+
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 class Migration38_39 implements Migration<Connection> {
 
@@ -38,8 +40,16 @@ class Migration38_39 implements Migration<Connection> {
 					+ " ALTER COLUMN contactId"
 					+ " SET NOT NULL");
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			throw new DbException(e);
 		}
 	}
+
+	private void tryToClose(@Nullable Statement s) {
+		try {
+			if (s != null) s.close();
+		} catch (SQLException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Migration39_40.java

@@ -7,8 +7,10 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
+
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 class Migration39_40 implements Migration<Connection> {
 
@@ -37,8 +39,16 @@ class Migration39_40 implements Migration<Connection> {
 					+ " ALTER COLUMN eta"
 					+ " SET NOT NULL");
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			throw new DbException(e);
 		}
 	}
+
+	private void tryToClose(@Nullable Statement s) {
+		try {
+			if (s != null) s.close();
+		} catch (SQLException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Migration40_41.java

@@ -1,46 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.db.DbException;
-
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Logger;
-
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
-
-class Migration40_41 implements Migration<Connection> {
-
-	private static final Logger LOG = getLogger(Migration40_41.class.getName());
-
-	private final DatabaseTypes dbTypes;
-
-	public Migration40_41(DatabaseTypes databaseTypes) {
-		this.dbTypes = databaseTypes;
-	}
-
-	@Override
-	public int getStartVersion() {
-		return 40;
-	}
-
-	@Override
-	public int getEndVersion() {
-		return 41;
-	}
-
-	@Override
-	public void migrate(Connection txn) throws DbException {
-		Statement s = null;
-		try {
-			s = txn.createStatement();
-			s.execute("ALTER TABLE contacts"
-					+ dbTypes.replaceTypes(" ADD alias _STRING"));
-		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-}

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

@@ -1,21 +1,29 @@
 package org.briarproject.bramble.identity;
 
+import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyPair;
 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.identity.Author.Status;
 import org.briarproject.bramble.api.identity.AuthorFactory;
+import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import java.util.Collection;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.identity.Author.Status.OURSELVES;
+import static org.briarproject.bramble.api.identity.Author.Status.UNKNOWN;
+import static org.briarproject.bramble.api.identity.Author.Status.UNVERIFIED;
+import static org.briarproject.bramble.api.identity.Author.Status.VERIFIED;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
 
@@ -67,16 +75,27 @@ class IdentityManagerImpl implements IdentityManager {
 			LOG.info("No local author to store");
 			return;
 		}
-		db.transaction(false, txn -> db.addLocalAuthor(txn, cached));
-		LOG.info("Local author stored");
+		Transaction txn = db.startTransaction(false);
+		try {
+			db.addLocalAuthor(txn, cached);
+			db.commitTransaction(txn);
+			LOG.info("Local author stored");
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 
 	@Override
 	public LocalAuthor getLocalAuthor() throws DbException {
 		if (cachedAuthor == null) {
-			cachedAuthor =
-					db.transactionWithResult(true, this::loadLocalAuthor);
-			LOG.info("Local author loaded");
+			Transaction txn = db.startTransaction(true);
+			try {
+				cachedAuthor = loadLocalAuthor(txn);
+				LOG.info("Local author loaded");
+				db.commitTransaction(txn);
+			} finally {
+				db.endTransaction(txn);
+			}
 		}
 		LocalAuthor cached = cachedAuthor;
 		if (cached == null) throw new AssertionError();
@@ -99,4 +118,26 @@ class IdentityManagerImpl implements IdentityManager {
 		return db.getLocalAuthors(txn).iterator().next();
 	}
 
+	@Override
+	public Status getAuthorStatus(AuthorId authorId) throws DbException {
+		Transaction txn = db.startTransaction(true);
+		try {
+			return getAuthorStatus(txn, authorId);
+		} finally {
+			db.endTransaction(txn);
+		}
+	}
+
+	@Override
+	public Status getAuthorStatus(Transaction txn, AuthorId authorId)
+			throws DbException {
+		if (getLocalAuthor(txn).getId().equals(authorId)) return OURSELVES;
+		Collection<Contact> contacts = db.getContactsByAuthorId(txn, authorId);
+		if (contacts.isEmpty()) return UNKNOWN;
+		for (Contact c : contacts) {
+			if (c.isVerified()) return VERIFIED;
+		}
+		return UNVERIFIED;
+	}
+
 }

bramble-core/src/main/java/org/briarproject/bramble/lifecycle/LifecycleManagerImpl.java

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
@@ -28,7 +29,6 @@ import javax.inject.Inject;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.COMPACTING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.MIGRATING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING;
@@ -114,16 +114,20 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 			dbLatch.countDown();
 			eventBus.broadcast(new LifecycleEvent(STARTING_SERVICES));
 
-			db.transaction(false, txn -> {
+			Transaction txn = db.startTransaction(false);
+			try {
 				for (Client c : clients) {
-					long start1 = now();
+					start = now();
 					c.createLocalState(txn);
 					if (LOG.isLoggable(FINE)) {
 						logDuration(LOG, "Starting client "
-								+ c.getClass().getSimpleName(), start1);
+								+ c.getClass().getSimpleName(), start);
 					}
 				}
-			});
+				db.commitTransaction(txn);
+			} finally {
+				db.endTransaction(txn);
+			}
 			for (Service s : services) {
 				start = now();
 				s.startService();
@@ -155,17 +159,11 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 	}
 
 	@Override
-	public void onDatabaseMigration() {
+	public void onMigrationRun() {
 		state = MIGRATING_DATABASE;
 		eventBus.broadcast(new LifecycleEvent(MIGRATING_DATABASE));
 	}
 
-	@Override
-	public void onDatabaseCompaction() {
-		state = COMPACTING_DATABASE;
-		eventBus.broadcast(new LifecycleEvent(COMPACTING_DATABASE));
-	}
-
 	@Override
 	public void stopServices() {
 		try {

bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothPlugin.java

@@ -23,6 +23,7 @@ import org.briarproject.bramble.api.plugin.event.EnableBluetoothEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
 import java.security.SecureRandom;
@@ -45,9 +46,6 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
-import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
-import static org.briarproject.bramble.util.StringUtils.macToBytes;
-import static org.briarproject.bramble.util.StringUtils.macToString;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -98,9 +96,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection connectTo(String address, String uuid)
 			throws IOException;
 
-	@Nullable
-	abstract DuplexTransportConnection discoverAndConnect(String uuid);
-
 	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
 			Executor ioExecutor, SecureRandom secureRandom,
 			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
@@ -198,7 +193,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			address = getBluetoothAddress();
 			if (LOG.isLoggable(INFO))
 				LOG.info("Local address " + scrubMacAddress(address));
-			if (!isNullOrEmpty(address)) {
+			if (!StringUtils.isNullOrEmpty(address)) {
 				p.put(PROP_ADDRESS, address);
 				changed = true;
 			}
@@ -261,9 +256,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		// Try to connect to known devices in parallel
 		for (Entry<ContactId, TransportProperties> e : contacts.entrySet()) {
 			String address = e.getValue().get(PROP_ADDRESS);
-			if (isNullOrEmpty(address)) continue;
+			if (StringUtils.isNullOrEmpty(address)) continue;
 			String uuid = e.getValue().get(PROP_UUID);
-			if (isNullOrEmpty(uuid)) continue;
+			if (StringUtils.isNullOrEmpty(uuid)) continue;
 			ContactId c = e.getKey();
 			ioExecutor.execute(() -> {
 				if (!isRunning() || !shouldAllowContactConnections()) return;
@@ -314,9 +309,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		if (!isRunning() || !shouldAllowContactConnections()) return null;
 		if (!connectionLimiter.canOpenContactConnection()) return null;
 		String address = p.get(PROP_ADDRESS);
-		if (isNullOrEmpty(address)) return null;
+		if (StringUtils.isNullOrEmpty(address)) return null;
 		String uuid = p.get(PROP_UUID);
-		if (isNullOrEmpty(uuid)) return null;
+		if (StringUtils.isNullOrEmpty(uuid)) return null;
 		DuplexTransportConnection conn = connect(address, uuid);
 		if (conn == null) return null;
 		// TODO: Why don't we reset the backoff here?
@@ -331,6 +326,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
 		if (!isRunning()) return null;
+		// There's no point listening if we can't discover our own address
+		String address = getBluetoothAddress();
+		if (address == null) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
@@ -348,8 +346,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		}
 		BdfList descriptor = new BdfList();
 		descriptor.add(TRANSPORT_ID_BLUETOOTH);
-		String address = getBluetoothAddress();
-		if (address != null) descriptor.add(macToBytes(address));
+		descriptor.add(StringUtils.macToBytes(address));
 		return new BluetoothKeyAgreementListener(descriptor, ss);
 	}
 
@@ -357,25 +354,18 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
+		String address;
+		try {
+			address = parseAddress(descriptor);
+		} catch (FormatException e) {
+			LOG.info("Invalid address in key agreement descriptor");
+			return null;
+		}
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
-		DuplexTransportConnection conn;
-		if (descriptor.size() == 1) {
-			if (LOG.isLoggable(INFO))
-				LOG.info("Discovering address for key agreement UUID " + uuid);
-			conn = discoverAndConnect(uuid);
-		} else {
-			String address;
-			try {
-				address = parseAddress(descriptor);
-			} catch (FormatException e) {
-				LOG.info("Invalid address in key agreement descriptor");
-				return null;
-			}
-			if (LOG.isLoggable(INFO))
-				LOG.info("Connecting to key agreement UUID " + uuid);
-			conn = connect(address, uuid);
-		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Connecting to key agreement UUID " + uuid);
+		DuplexTransportConnection conn = connect(address, uuid);
 		if (conn != null) connectionLimiter.keyAgreementConnectionOpened(conn);
 		return conn;
 	}
@@ -383,7 +373,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private String parseAddress(BdfList descriptor) throws FormatException {
 		byte[] mac = descriptor.getRaw(1);
 		if (mac.length != 6) throw new FormatException();
-		return macToString(mac);
+		return StringUtils.macToString(mac);
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FileTransportReader.java

@@ -4,11 +4,12 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 class FileTransportReader implements TransportConnectionReader {
@@ -33,7 +34,11 @@ class FileTransportReader implements TransportConnectionReader {
 
 	@Override
 	public void dispose(boolean exception, boolean recognised) {
-		tryToClose(in, LOG, WARNING);
+		try {
+			in.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
 		plugin.readerFinished(file, exception, recognised);
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FileTransportWriter.java

@@ -4,11 +4,12 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.OutputStream;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 class FileTransportWriter implements TransportConnectionWriter {
@@ -43,7 +44,11 @@ class FileTransportWriter implements TransportConnectionWriter {
 
 	@Override
 	public void dispose(boolean exception) {
-		tryToClose(out, LOG, WARNING);
+		try {
+			out.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
 		plugin.writerFinished(file, exception);
 	}
 }

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

@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
@@ -36,6 +35,7 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PREF_LAN_IP_PORTS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PROP_IP_PORTS;
 import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
+import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 
 @NotNullByDefault
@@ -293,7 +293,11 @@ class LanTcpPlugin extends TcpPlugin {
 
 		@Override
 		public void close() {
-			IoUtils.tryToClose(ss, LOG, WARNING);
+			try {
+				ss.close();
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+			}
 		}
 	}
 

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

@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
@@ -154,8 +153,13 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 
 	protected void tryToClose(@Nullable ServerSocket ss) {
-		IoUtils.tryToClose(ss, LOG, WARNING);
-		callback.transportDisabled();
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		} finally {
+			callback.transportDisabled();
+		}
 	}
 
 	String getIpPortString(InetSocketAddress a) {

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/CircumventionProvider.java

@@ -17,24 +17,16 @@ public interface CircumventionProvider {
 	String[] BLOCKED = {"CN", "IR", "EG", "BY", "TR", "SY", "VE"};
 
 	/**
-	 * Countries where obfs4 bridge connection are likely to work.
+	 * Countries where vanilla bridge connection are likely to work.
 	 * Should be a subset of {@link #BLOCKED}.
 	 */
-	String[] BRIDGES = { "CN", "IR", "EG", "BY", "TR", "SY", "VE" };
-
-	/**
-	 * Countries where obfs4 bridges won't work and meek is needed.
-	 * Should be a subset of {@link #BRIDGES}.
-	 */
-	String[] NEEDS_MEEK = {"CN", "IR"};
+	String[] BRIDGES = { "EG", "BY", "TR", "SY", "VE" };
 
 	boolean isTorProbablyBlocked(String countryCode);
 
 	boolean doBridgesWork(String countryCode);
 
-	boolean needsMeek(String countryCode);
-
 	@IoExecutor
-	List<String> getBridges(boolean meek);
+	List<String> getBridges();
 
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/CircumventionProviderImpl.java

@@ -22,8 +22,6 @@ class CircumventionProviderImpl implements CircumventionProvider {
 			new HashSet<>(asList(BLOCKED));
 	private static final Set<String> BRIDGES_WORK_IN_COUNTRIES =
 			new HashSet<>(asList(BRIDGES));
-	private static final Set<String> BRIDGES_NEED_MEEK =
-			new HashSet<>(asList(NEEDS_MEEK));
 
 	@Nullable
 	private volatile List<String> bridges = null;
@@ -42,14 +40,9 @@ class CircumventionProviderImpl implements CircumventionProvider {
 		return BRIDGES_WORK_IN_COUNTRIES.contains(countryCode);
 	}
 
-	@Override
-	public boolean needsMeek(String countryCode) {
-		return BRIDGES_NEED_MEEK.contains(countryCode);
-	}
-
 	@Override
 	@IoExecutor
-	public List<String> getBridges(boolean useMeek) {
+	public List<String> getBridges() {
 		List<String> bridges = this.bridges;
 		if (bridges != null) return new ArrayList<>(bridges);
 
@@ -60,8 +53,6 @@ class CircumventionProviderImpl implements CircumventionProvider {
 		bridges = new ArrayList<>();
 		while (scanner.hasNextLine()) {
 			String line = scanner.nextLine();
-			boolean isMeekBridge = line.startsWith("Bridge meek");
-			if (useMeek && !isMeekBridge || !useMeek && isMeekBridge) continue;
 			if (!line.startsWith("#")) bridges.add(line);
 		}
 		scanner.close();

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

@@ -4,8 +4,6 @@ import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
 import org.briarproject.bramble.PoliteExecutor;
-import org.briarproject.bramble.api.battery.BatteryManager;
-import org.briarproject.bramble.api.battery.event.BatteryEvent;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -30,7 +28,9 @@ import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 import org.briarproject.bramble.util.IoUtils;
+import org.briarproject.bramble.util.StringUtils;
 
+import java.io.Closeable;
 import java.io.EOFException;
 import java.io.File;
 import java.io.FileInputStream;
@@ -69,13 +69,10 @@ import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_AUTOMATIC;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_NEVER;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_WITH_BRIDGES;
-import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_PORT;
-import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V2;
-import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V3;
+import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubOnion;
-import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -90,22 +87,20 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final String OWNER = "__OwningControllerProcess";
 	private static final int COOKIE_TIMEOUT_MS = 3000;
 	private static final int COOKIE_POLLING_INTERVAL_MS = 200;
-	private static final Pattern ONION_V2 = Pattern.compile("[a-z2-7]{16}");
-	private static final Pattern ONION_V3 = Pattern.compile("[a-z2-7]{56}");
+	private static final Pattern ONION = Pattern.compile("[a-z2-7]{16}");
 
 	private final Executor ioExecutor, connectionStatusExecutor;
 	private final NetworkManager networkManager;
 	private final LocationUtils locationUtils;
 	private final SocketFactory torSocketFactory;
 	private final Clock clock;
-	private final BatteryManager batteryManager;
 	private final Backoff backoff;
 	private final DuplexPluginCallback callback;
 	private final String architecture;
 	private final CircumventionProvider circumventionProvider;
 	private final ResourceProvider resourceProvider;
 	private final int maxLatency, maxIdleTime, socketTimeout;
-	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
+	private final File torDirectory, torFile, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final ConnectionStatus connectionStatus;
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -124,8 +119,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	TorPlugin(Executor ioExecutor, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager, Backoff backoff,
+			CircumventionProvider circumventionProvider, Backoff backoff,
 			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime, File torDirectory) {
 		this.ioExecutor = ioExecutor;
@@ -135,7 +129,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		this.clock = clock;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
-		this.batteryManager = batteryManager;
 		this.backoff = backoff;
 		this.callback = callback;
 		this.architecture = architecture;
@@ -147,7 +140,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		this.torDirectory = torDirectory;
 		torFile = new File(torDirectory, "tor");
 		geoIpFile = new File(torDirectory, "geoip");
-		obfs4File = new File(torDirectory, "obfs4proxy");
 		configFile = new File(torDirectory, "torrc");
 		doneFile = new File(torDirectory, "done");
 		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
@@ -266,8 +258,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			throw new PluginException(e);
 		}
 		// Check whether we're online
-		updateConnectionStatus(networkManager.getNetworkStatus(),
-				batteryManager.isCharging());
+		updateConnectionStatus(networkManager.getNetworkStatus());
 		// Bind a server socket to receive incoming hidden service connections
 		bind();
 	}
@@ -291,20 +282,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			in = getGeoIpInputStream();
 			out = new FileOutputStream(geoIpFile);
 			IoUtils.copyAndClose(in, out);
-			// Unzip the Obfs4 proxy to the filesystem
-			in = getObfs4InputStream();
-			out = new FileOutputStream(obfs4File);
-			IoUtils.copyAndClose(in, out);
-			// Make the Obfs4 proxy executable
-			if (!obfs4File.setExecutable(true, true)) throw new IOException();
 			// Copy the config file to the filesystem
 			in = getConfigInputStream();
 			out = new FileOutputStream(configFile);
 			IoUtils.copyAndClose(in, out);
 			doneFile.createNewFile();
 		} catch (IOException e) {
-			IoUtils.tryToClose(in, LOG, WARNING);
-			IoUtils.tryToClose(out, LOG, WARNING);
+			tryToClose(in);
+			tryToClose(out);
 			throw new PluginException(e);
 		}
 	}
@@ -327,20 +312,26 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		return zin;
 	}
 
-	private InputStream getObfs4InputStream() throws IOException {
-		if (LOG.isLoggable(INFO))
-			LOG.info("Installing obfs4proxy binary for " + architecture);
-		InputStream in = resourceProvider
-				.getResourceInputStream("obfs4proxy_" + architecture, ".zip");
-		ZipInputStream zin = new ZipInputStream(in);
-		if (zin.getNextEntry() == null) throw new IOException();
-		return zin;
-	}
-
 	private InputStream getConfigInputStream() {
 		return getClass().getClassLoader().getResourceAsStream("torrc");
 	}
 
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	private void tryToClose(@Nullable Socket s) {
+		try {
+			if (s != null) s.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
 	private void listFiles(File f) {
 		if (f.isDirectory()) {
 			File[] children = f.listFiles();
@@ -362,7 +353,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			}
 			return b;
 		} finally {
-			IoUtils.tryToClose(in, LOG, WARNING);
+			tryToClose(in);
 		}
 	}
 
@@ -371,7 +362,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			// If there's already a port number stored in config, reuse it
 			String portString = settings.get(PREF_TOR_PORT);
 			int port;
-			if (isNullOrEmpty(portString)) port = 0;
+			if (StringUtils.isNullOrEmpty(portString)) port = 0;
 			else port = Integer.parseInt(portString);
 			// Bind a server socket to receive connections from Tor
 			ServerSocket ss = null;
@@ -402,8 +393,13 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void tryToClose(@Nullable ServerSocket ss) {
-		IoUtils.tryToClose(ss, LOG, WARNING);
-		callback.transportDisabled();
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		} finally {
+			callback.transportDisabled();
+		}
 	}
 
 	private void publishHiddenService(String port) {
@@ -431,11 +427,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			return;
 		}
 		// Publish the hidden service's onion hostname in transport properties
-		String onion2 = response.get(HS_ADDRESS);
+		String hostname = response.get(HS_ADDRESS);
 		if (LOG.isLoggable(INFO))
-			LOG.info("Hidden service " + scrubOnion(onion2));
+			LOG.info("Hidden service " + scrubOnion(hostname));
 		TransportProperties p = new TransportProperties();
-		p.put(PROP_ONION_V2, onion2);
+		p.put(PROP_ONION, hostname);
 		callback.mergeLocalProperties(p);
 		if (privKey == null) {
 			// Save the hidden service's private key for next time
@@ -470,19 +466,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (!enable) callback.transportDisabled();
 	}
 
-	private void enableBridges(boolean enable, boolean needsMeek)
-			throws IOException {
+	private void enableBridges(boolean enable) throws IOException {
 		if (enable) {
 			Collection<String> conf = new ArrayList<>();
 			conf.add("UseBridges 1");
-			if (needsMeek) {
-				conf.add("ClientTransportPlugin meek_lite exec " +
-						obfs4File.getAbsolutePath());
-			} else {
-				conf.add("ClientTransportPlugin obfs4 exec " +
-						obfs4File.getAbsolutePath());
-			}
-			conf.addAll(circumventionProvider.getBridges(needsMeek));
+			conf.addAll(circumventionProvider.getBridges());
 			controlConnection.setConf(conf);
 		} else {
 			controlConnection.setConf("UseBridges", "0");
@@ -542,43 +530,28 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
 		if (!isRunning()) return null;
-		String bestOnion = null;
-		String onion2 = p.get(PROP_ONION_V2);
-		String onion3 = p.get(PROP_ONION_V3);
-		if (!isNullOrEmpty(onion2)) {
-			if (ONION_V2.matcher(onion2).matches()) {
-				bestOnion = onion2;
-			} else {
-				// Don't scrub the address so we can find the problem
-				if (LOG.isLoggable(INFO))
-					LOG.info("Invalid v2 hostname: " + onion2);
-			}
+		String onion = p.get(PROP_ONION);
+		if (StringUtils.isNullOrEmpty(onion)) return null;
+		if (!ONION.matcher(onion).matches()) {
+			// not scrubbing this address, so we are able to find the problem
+			if (LOG.isLoggable(INFO)) LOG.info("Invalid hostname: " + onion);
+			return null;
 		}
-		if (!isNullOrEmpty(onion3)) {
-			if (ONION_V3.matcher(onion3).matches()) {
-				bestOnion = onion3;
-			} else {
-				// Don't scrub the address so we can find the problem
-				if (LOG.isLoggable(INFO))
-					LOG.info("Invalid v3 hostname: " + onion3);
-			}
-		}
-		if (bestOnion == null) return null;
 		Socket s = null;
 		try {
 			if (LOG.isLoggable(INFO))
-				LOG.info("Connecting to " + scrubOnion(bestOnion));
-			s = torSocketFactory.createSocket(bestOnion + ".onion", 80);
+				LOG.info("Connecting to " + scrubOnion(onion));
+			s = torSocketFactory.createSocket(onion + ".onion", 80);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
-				LOG.info("Connected to " + scrubOnion(bestOnion));
+				LOG.info("Connected to " + scrubOnion(onion));
 			return new TorTransportConnection(this, s);
 		} catch (IOException e) {
 			if (LOG.isLoggable(INFO)) {
-				LOG.info("Could not connect to " + scrubOnion(bestOnion)
-						+ ": " + e.toString());
+				LOG.info("Could not connect to " + scrubOnion(onion) + ": " +
+						e.toString());
 			}
-			IoUtils.tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			return null;
 		}
 	}
@@ -619,8 +592,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			LOG.info("OR connection " + status + " " + orName);
 		if (status.equals("CLOSED") || status.equals("FAILED")) {
 			// Check whether we've lost connectivity
-			updateConnectionStatus(networkManager.getNetworkStatus(),
-					batteryManager.isCharging());
+			updateConnectionStatus(networkManager.getNetworkStatus());
 		}
 	}
 
@@ -655,35 +627,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (s.getNamespace().equals(ID.getString())) {
 				LOG.info("Tor settings updated");
 				settings = s.getSettings();
-				// Works around a bug introduced in Tor 0.3.4.8.
-				// https://trac.torproject.org/projects/tor/ticket/28027
-				// Could be replaced with callback.transportDisabled()
-				// when fixed.
-				disableNetwork();
-				updateConnectionStatus(networkManager.getNetworkStatus(),
-						batteryManager.isCharging());
+				updateConnectionStatus(networkManager.getNetworkStatus());
 			}
 		} else if (e instanceof NetworkStatusEvent) {
-			updateConnectionStatus(((NetworkStatusEvent) e).getStatus(),
-					batteryManager.isCharging());
-		} else if (e instanceof BatteryEvent) {
-			updateConnectionStatus(networkManager.getNetworkStatus(),
-					((BatteryEvent) e).isCharging());
+			updateConnectionStatus(((NetworkStatusEvent) e).getStatus());
 		}
 	}
 
-	private void disableNetwork() {
-		connectionStatusExecutor.execute(() -> {
-			try {
-				enableNetwork(false);
-			} catch (IOException ex) {
-				logException(LOG, WARNING, ex);
-			}
-		});
-	}
-
-	private void updateConnectionStatus(NetworkStatus status,
-			boolean charging) {
+	private void updateConnectionStatus(NetworkStatus status) {
 		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
 			boolean online = status.isConnected();
@@ -694,8 +645,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			int network = settings.getInt(PREF_TOR_NETWORK,
 					PREF_TOR_NETWORK_AUTOMATIC);
 			boolean useMobile = settings.getBoolean(PREF_TOR_MOBILE, true);
-			boolean onlyWhenCharging =
-					settings.getBoolean(PREF_TOR_ONLY_WHEN_CHARGING, false);
 			boolean bridgesWork = circumventionProvider.doBridgesWork(country);
 			boolean automatic = network == PREF_TOR_NETWORK_AUTOMATIC;
 
@@ -703,56 +652,35 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
 				if ("".equals(country)) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
-				LOG.info("Charging: " + charging);
 			}
 
 			try {
 				if (!online) {
 					LOG.info("Disabling network, device is offline");
 					enableNetwork(false);
-				} else if (!charging && onlyWhenCharging) {
-					LOG.info("Disabling network, device is on battery");
-					enableNetwork(false);
 				} else if (network == PREF_TOR_NETWORK_NEVER ||
 						(!useMobile && !wifi)) {
-					LOG.info("Disabling network, device is using mobile data");
+					LOG.info("Disabling network due to setting");
 					enableNetwork(false);
 				} else if (automatic && blocked && !bridgesWork) {
 					LOG.info("Disabling network, country is blocked");
 					enableNetwork(false);
 				} else if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
 						(automatic && bridgesWork)) {
-					if (circumventionProvider.needsMeek(country)) {
-						LOG.info("Enabling network, using meek bridges");
-						enableBridges(true, true);
-					} else {
-						LOG.info("Enabling network, using obfs4 bridges");
-						enableBridges(true, false);
-					}
+					LOG.info("Enabling network, using bridges");
+					enableBridges(true);
 					enableNetwork(true);
 				} else {
 					LOG.info("Enabling network, not using bridges");
-					enableBridges(false, false);
+					enableBridges(false);
 					enableNetwork(true);
 				}
-				if (online && wifi && charging) {
-					LOG.info("Enabling connection padding");
-					enableConnectionPadding(true);
-				} else {
-					LOG.info("Disabling connection padding");
-					enableConnectionPadding(false);
-				}
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		});
 	}
 
-	private void enableConnectionPadding(boolean enable) throws IOException {
-		if (!running) return;
-		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
-	}
-
 	// TODO remove when sufficient time has passed. Added 2018-08-15
 	private void migrateSettings() {
 		Settings sOld = callback.getSettings();

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

@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.data.MetadataEncoder;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
-import org.briarproject.bramble.api.sync.validation.ValidationManager;
+import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 

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

@@ -24,7 +24,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
@@ -142,7 +142,15 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public Map<TransportId, TransportProperties> getLocalProperties()
 			throws DbException {
-		return db.transactionWithResult(true, this::getLocalProperties);
+		Map<TransportId, TransportProperties> local;
+		Transaction txn = db.startTransaction(true);
+		try {
+			local = getLocalProperties(txn);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return local;
 	}
 
 	@Override
@@ -168,8 +176,9 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public TransportProperties getLocalProperties(TransportId t)
 			throws DbException {
 		try {
-			return db.transactionWithResult(true, txn -> {
-				TransportProperties p = null;
+			TransportProperties p = null;
+			Transaction txn = db.startTransaction(true);
+			try {
 				// Find the latest local update
 				LatestUpdate latest = findLatest(txn, localGroup.getId(), t,
 						true);
@@ -179,8 +188,11 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 							latest.messageId);
 					p = parseProperties(message);
 				}
-				return p == null ? new TransportProperties() : p;
-			});
+				db.commitTransaction(txn);
+			} finally {
+				db.endTransaction(txn);
+			}
+			return p == null ? new TransportProperties() : p;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -189,12 +201,16 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public Map<ContactId, TransportProperties> getRemoteProperties(
 			TransportId t) throws DbException {
-		return db.transactionWithResult(true, txn -> {
-			Map<ContactId, TransportProperties> remote = new HashMap<>();
+		Map<ContactId, TransportProperties> remote = new HashMap<>();
+		Transaction txn = db.startTransaction(true);
+		try {
 			for (Contact c : db.getContacts(txn))
 				remote.put(c.getId(), getRemoteProperties(txn, c, t));
-			return remote;
-		});
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return remote;
 	}
 
 	private TransportProperties getRemoteProperties(Transaction txn, Contact c,
@@ -218,15 +234,23 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException {
-		return db.transactionWithResult(true, txn ->
-				getRemoteProperties(txn, db.getContact(txn, c), t));
+		TransportProperties p;
+		Transaction txn = db.startTransaction(true);
+		try {
+			p = getRemoteProperties(txn, db.getContact(txn, c), t);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return p;
 	}
 
 	@Override
 	public void mergeLocalProperties(TransportId t, TransportProperties p)
 			throws DbException {
 		try {
-			db.transaction(false, txn -> {
+			Transaction txn = db.startTransaction(false);
+			try {
 				// Merge the new properties with any existing properties
 				TransportProperties merged;
 				boolean changed;
@@ -263,7 +287,10 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 							db.removeMessage(txn, latest.messageId);
 					}
 				}
-			});
+				db.commitTransaction(txn);
+			} finally {
+				db.endTransaction(txn);
+			}
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

bramble-core/src/main/java/org/briarproject/bramble/reporting/DevReporterImpl.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
+import java.io.Closeable;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -25,12 +26,13 @@ import java.net.Socket;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @Immutable
 @NotNullByDefault
@@ -64,7 +66,7 @@ class DevReporterImpl implements DevReporter, EventListener {
 			s.setSoTimeout(SOCKET_TIMEOUT);
 			return s;
 		} catch (IOException e) {
-			tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			throw e;
 		}
 	}
@@ -86,7 +88,8 @@ class DevReporterImpl implements DevReporter, EventListener {
 			writer.append(armoured);
 			writer.flush();
 		} finally {
-			tryToClose(writer, LOG, WARNING);
+			if (writer != null)
+				writer.close();
 		}
 	}
 
@@ -118,11 +121,27 @@ class DevReporterImpl implements DevReporter, EventListener {
 				f.delete();
 			} catch (IOException e) {
 				LOG.log(WARNING, "Failed to send reports", e);
-				tryToClose(out, LOG, WARNING);
-				tryToClose(in, LOG, WARNING);
+				tryToClose(out);
+				tryToClose(in);
 				return;
 			}
 		}
 		LOG.info("Reports sent");
 	}
+
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	private void tryToClose(@Nullable Socket s) {
+		try {
+			if (s != null) s.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/settings/SettingsManagerImpl.java

@@ -23,8 +23,15 @@ class SettingsManagerImpl implements SettingsManager {
 
 	@Override
 	public Settings getSettings(String namespace) throws DbException {
-		return db.transactionWithResult(true, txn ->
-				db.getSettings(txn, namespace));
+		Settings s;
+		Transaction txn = db.startTransaction(true);
+		try {
+			s = db.getSettings(txn, namespace);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return s;
 	}
 
 	@Override
@@ -35,6 +42,12 @@ class SettingsManagerImpl implements SettingsManager {
 
 	@Override
 	public void mergeSettings(Settings s, String namespace) throws DbException {
-		db.transaction(false, txn -> db.mergeSettings(txn, s, namespace));
+		Transaction txn = db.startTransaction(false);
+		try {
+			db.mergeSettings(txn, s, namespace);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
 	}
 }

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -229,8 +230,14 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			if (!generateAckQueued.getAndSet(false)) throw new AssertionError();
 			try {
-				Ack a = db.transactionWithNullableResult(false, txn ->
-						db.generateAck(txn, contactId, MAX_MESSAGE_IDS));
+				Ack a;
+				Transaction txn = db.startTransaction(false);
+				try {
+					a = db.generateAck(txn, contactId, MAX_MESSAGE_IDS);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated ack: " + (a != null));
 				if (a != null) writerTasks.add(new WriteAck(a));
@@ -268,15 +275,16 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateBatchQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Collection<Message> b =
-						db.transactionWithNullableResult(false, txn -> {
-							Collection<Message> batch =
-									db.generateRequestedBatch(txn, contactId,
-											MAX_RECORD_PAYLOAD_BYTES,
-											maxLatency);
-							setNextSendTime(db.getNextSendTime(txn, contactId));
-							return batch;
-						});
+				Collection<Message> b;
+				Transaction txn = db.startTransaction(false);
+				try {
+					b = db.generateRequestedBatch(txn, contactId,
+							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
+					setNextSendTime(db.getNextSendTime(txn, contactId));
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b != null) writerTasks.add(new WriteBatch(b));
@@ -314,12 +322,16 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateOfferQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Offer o = db.transactionWithNullableResult(false, txn -> {
-					Offer offer = db.generateOffer(txn, contactId,
-							MAX_MESSAGE_IDS, maxLatency);
+				Offer o;
+				Transaction txn = db.startTransaction(false);
+				try {
+					o = db.generateOffer(txn, contactId, MAX_MESSAGE_IDS,
+							maxLatency);
 					setNextSendTime(db.getNextSendTime(txn, contactId));
-					return offer;
-				});
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated offer: " + (o != null));
 				if (o != null) writerTasks.add(new WriteOffer(o));
@@ -357,8 +369,14 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateRequestQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Request r = db.transactionWithNullableResult(false, txn ->
-						db.generateRequest(txn, contactId, MAX_MESSAGE_IDS));
+				Request r;
+				Transaction txn = db.startTransaction(false);
+				try {
+					r = db.generateRequest(txn, contactId, MAX_MESSAGE_IDS);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated request: " + (r != null));
 				if (r != null) writerTasks.add(new WriteRequest(r));

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

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -119,8 +120,13 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				db.transaction(false, txn ->
-						db.receiveAck(txn, contactId, ack));
+				Transaction txn = db.startTransaction(false);
+				try {
+					db.receiveAck(txn, contactId, ack);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -140,8 +146,13 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				db.transaction(false, txn ->
-						db.receiveMessage(txn, contactId, message));
+				Transaction txn = db.startTransaction(false);
+				try {
+					db.receiveMessage(txn, contactId, message);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -161,8 +172,13 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				db.transaction(false, txn ->
-						db.receiveOffer(txn, contactId, offer));
+				Transaction txn = db.startTransaction(false);
+				try {
+					db.receiveOffer(txn, contactId, offer);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -182,8 +198,13 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				db.transaction(false, txn ->
-						db.receiveRequest(txn, contactId, request));
+				Transaction txn = db.startTransaction(false);
+				try {
+					db.receiveRequest(txn, contactId, request);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();

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

@@ -36,7 +36,6 @@ class MessageFactoryImpl implements MessageFactory {
 
 	@Override
 	public Message createMessage(GroupId g, long timestamp, byte[] body) {
-		if (body.length == 0) throw new IllegalArgumentException();
 		if (body.length > MAX_MESSAGE_BODY_LENGTH)
 			throw new IllegalArgumentException();
 		MessageId id = getMessageId(g, timestamp, body);
@@ -55,7 +54,7 @@ class MessageFactoryImpl implements MessageFactory {
 
 	@Override
 	public Message createMessage(byte[] raw) {
-		if (raw.length <= MESSAGE_HEADER_LENGTH)
+		if (raw.length < MESSAGE_HEADER_LENGTH)
 			throw new IllegalArgumentException();
 		if (raw.length > MAX_MESSAGE_LENGTH)
 			throw new IllegalArgumentException();

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -46,8 +47,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(SimplexOutgoingSession.class.getName());
 
-	private static final ThrowingRunnable<IOException> CLOSE = () -> {
-	};
+	private static final ThrowingRunnable<IOException> CLOSE = () -> {};
 
 	private final DatabaseComponent db;
 	private final Executor dbExecutor;
@@ -128,8 +128,14 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		public void run() {
 			if (interrupted) return;
 			try {
-				Ack a = db.transactionWithNullableResult(false, txn ->
-						db.generateAck(txn, contactId, MAX_MESSAGE_IDS));
+				Ack a;
+				Transaction txn = db.startTransaction(false);
+				try {
+					a = db.generateAck(txn, contactId, MAX_MESSAGE_IDS);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated ack: " + (a != null));
 				if (a == null) decrementOutstandingQueries();
@@ -166,10 +172,15 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		public void run() {
 			if (interrupted) return;
 			try {
-				Collection<Message> b =
-						db.transactionWithNullableResult(false, txn ->
-								db.generateBatch(txn, contactId,
-										MAX_RECORD_PAYLOAD_BYTES, maxLatency));
+				Collection<Message> b;
+				Transaction txn = db.startTransaction(false);
+				try {
+					b = db.generateBatch(txn, contactId,
+							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
+					db.commitTransaction(txn);
+				} finally {
+					db.endTransaction(txn);
+				}
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b == null) decrementOutstandingQueries();

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

@@ -1,11 +1,23 @@
 package org.briarproject.bramble.sync;
 
+import org.briarproject.bramble.PoliteExecutor;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.sync.GroupFactory;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
 import org.briarproject.bramble.api.sync.SyncRecordWriterFactory;
 import org.briarproject.bramble.api.sync.SyncSessionFactory;
+import org.briarproject.bramble.api.sync.ValidationManager;
+import org.briarproject.bramble.api.system.Clock;
 
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
 import javax.inject.Singleton;
 
 import dagger.Module;
@@ -14,14 +26,29 @@ import dagger.Provides;
 @Module
 public class SyncModule {
 
+	public static class EagerSingletons {
+		@Inject
+		ValidationManager validationManager;
+	}
+
+	/**
+	 * The maximum number of validation tasks to delegate to the crypto
+	 * executor concurrently.
+	 * <p>
+	 * The number of available processors can change during the lifetime of the
+	 * JVM, so this is just a reasonable guess.
+	 */
+	private static final int MAX_CONCURRENT_VALIDATION_TASKS =
+			Math.max(1, Runtime.getRuntime().availableProcessors() - 1);
+
 	@Provides
-	GroupFactory provideGroupFactory(GroupFactoryImpl groupFactory) {
-		return groupFactory;
+	GroupFactory provideGroupFactory(CryptoComponent crypto) {
+		return new GroupFactoryImpl(crypto);
 	}
 
 	@Provides
-	MessageFactory provideMessageFactory(MessageFactoryImpl messageFactory) {
-		return messageFactory;
+	MessageFactory provideMessageFactory(CryptoComponent crypto) {
+		return new MessageFactoryImpl(crypto);
 	}
 
 	@Provides
@@ -38,8 +65,30 @@ public class SyncModule {
 
 	@Provides
 	@Singleton
-	SyncSessionFactory provideSyncSessionFactory(
-			SyncSessionFactoryImpl syncSessionFactory) {
-		return syncSessionFactory;
+	SyncSessionFactory provideSyncSessionFactory(DatabaseComponent db,
+			@DatabaseExecutor Executor dbExecutor, EventBus eventBus,
+			Clock clock, SyncRecordReaderFactory recordReaderFactory,
+			SyncRecordWriterFactory recordWriterFactory) {
+		return new SyncSessionFactoryImpl(db, dbExecutor, eventBus, clock,
+				recordReaderFactory, recordWriterFactory);
+	}
+
+	@Provides
+	@Singleton
+	ValidationManager provideValidationManager(
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			ValidationManagerImpl validationManager) {
+		lifecycleManager.registerService(validationManager);
+		eventBus.addListener(validationManager);
+		return validationManager;
+	}
+
+	@Provides
+	@Singleton
+	@ValidationExecutor
+	Executor provideValidationExecutor(
+			@CryptoExecutor Executor cryptoExecutor) {
+		return new PoliteExecutor("ValidationExecutor", cryptoExecutor,
+				MAX_CONCURRENT_VALIDATION_TASKS);
 	}
 }