Refactor layouts for alias and link dialogs.

This commit also uses LiveData Transformations to expose contact related information

.idea/runConfigurations/All_in_briar_headless.xml

@@ -3,7 +3,7 @@
     <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="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />

bramble-android/build.gradle

@@ -1,5 +1,3 @@
-import com.android.build.gradle.tasks.MergeResources
-
 apply plugin: 'com.android.library'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
@@ -11,8 +9,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 10105
-		versionName "1.1.5"
+		versionCode 10103
+		versionName "1.1.3"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -31,9 +29,8 @@ configurations {
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
 	tor 'org.briarproject:tor-android:0.3.4.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.7@zip'
 
-	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

@@ -9,22 +9,19 @@ import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
-
 class AndroidAccountManager extends AccountManagerImpl
 		implements AccountManager {
 
 	private static final Logger LOG =
-			getLogger(AndroidAccountManager.class.getName());
+			Logger.getLogger(AndroidAccountManager.class.getName());
 
 	private static final String PREF_DB_KEY = "key";
 
@@ -40,7 +37,7 @@ class AndroidAccountManager extends AccountManagerImpl
 		appContext = app.getApplicationContext();
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	@Override
 	@Nullable
 	protected String loadEncryptedDatabaseKey() {
@@ -50,7 +47,7 @@ class AndroidAccountManager extends AccountManagerImpl
 		return key;
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	@Nullable
 	private String getDatabaseKeyFromPreferences() {
 		String key = prefs.getString(PREF_DB_KEY, null);
@@ -59,7 +56,7 @@ class AndroidAccountManager extends AccountManagerImpl
 		return key;
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	private void migrateDatabaseKeyToFile(String key) {
 		if (storeEncryptedDatabaseKey(key)) {
 			if (prefs.edit().remove(PREF_DB_KEY).commit())
@@ -84,7 +81,7 @@ class AndroidAccountManager extends AccountManagerImpl
 		return PreferenceManager.getDefaultSharedPreferences(appContext);
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	private void deleteAppData(SharedPreferences... clear) {
 		// Clear and commit shared preferences
 		for (SharedPreferences prefs : clear) {
@@ -100,7 +97,7 @@ class AndroidAccountManager extends AccountManagerImpl
 			for (File child : children) {
 				String name = child.getName();
 				if (!name.equals("lib") && !name.equals("shared_prefs")) {
-					deleteFileOrDir(child);
+					IoUtils.deleteFileOrDir(child);
 				}
 			}
 		}

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/AndroidNetworkManager.java

@@ -13,7 +13,8 @@ import org.briarproject.bramble.api.lifecycle.Service;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.system.Scheduler;
 
 import java.util.concurrent.Future;
@@ -33,17 +34,16 @@ import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED;
-import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 class AndroidNetworkManager implements NetworkManager, Service {
 
 	private static final Logger LOG =
-			getLogger(AndroidNetworkManager.class.getName());
+			Logger.getLogger(AndroidNetworkManager.class.getName());
 
 	// See android.net.wifi.WifiManager
 	private static final String WIFI_AP_STATE_CHANGED_ACTION =
@@ -56,7 +56,6 @@ class AndroidNetworkManager implements NetworkManager, Service {
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	@Nullable
 	private volatile BroadcastReceiver networkStateReceiver = null;
 
 	@Inject
@@ -90,8 +89,9 @@ class AndroidNetworkManager implements NetworkManager, Service {
 
 	@Override
 	public NetworkStatus getNetworkStatus() {
-		ConnectivityManager cm = (ConnectivityManager) requireNonNull(
-				appContext.getSystemService(CONNECTIVITY_SERVICE));
+		ConnectivityManager cm = (ConnectivityManager)
+				appContext.getSystemService(CONNECTIVITY_SERVICE);
+		if (cm == null) throw new AssertionError();
 		NetworkInfo net = cm.getActiveNetworkInfo();
 		boolean connected = net != null && net.isConnected();
 		boolean wifi = connected && net.getType() == TYPE_WIFI;

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

@@ -18,12 +18,13 @@ 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;
@@ -47,11 +48,10 @@ 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.Collections.shuffle;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
@@ -59,7 +59,7 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	private static final Logger LOG =
-			getLogger(AndroidBluetoothPlugin.class.getName());
+			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
 
 	private static final int MAX_DISCOVERY_MS = 10_000;
 
@@ -161,7 +161,11 @@ 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
@@ -191,7 +195,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			s.connect();
 			return wrapSocket(s);
 		} catch (IOException e) {
-			IoUtils.tryToClose(s, LOG, WARNING);
+			tryToClose(s);
 			throw e;
 		}
 	}
@@ -260,10 +264,18 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			appContext.unregisterReceiver(receiver);
 		}
 		// Shuffle the addresses so we don't always try the same one first
-		shuffle(addresses);
+		Collections.shuffle(addresses);
 		return addresses;
 	}
 
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
 	private class BluetoothStateReceiver extends BroadcastReceiver {
 
 		@Override

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

@@ -32,19 +32,17 @@ import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
-import static java.util.Objects.requireNonNull;
-import static java.util.logging.Logger.getLogger;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
-	private static final Logger LOG =
-			getLogger(AndroidLanTcpPlugin.class.getName());
-
 	private static final byte[] WIFI_AP_ADDRESS_BYTES =
 			{(byte) 192, (byte) 168, 43, 1};
 	private static final InetAddress WIFI_AP_ADDRESS;
 
+	private static final Logger LOG =
+			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
+
 	static {
 		try {
 			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
@@ -68,8 +66,10 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("AndroidLanTcpPlugin", ioExecutor, 1);
-		connectivityManager = (ConnectivityManager) requireNonNull(
-				appContext.getSystemService(CONNECTIVITY_SERVICE));
+		ConnectivityManager connectivityManager = (ConnectivityManager)
+				appContext.getSystemService(CONNECTIVITY_SERVICE);
+		if (connectivityManager == null) throw new AssertionError();
+		this.connectivityManager = connectivityManager;
 		wifiManager = (WifiManager) appContext.getApplicationContext()
 				.getSystemService(WIFI_SERVICE);
 		socketFactory = SocketFactory.getDefault();

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

@@ -6,9 +6,9 @@ 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.NotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.system.Clock;
@@ -25,10 +25,10 @@ import javax.net.SocketFactory;
 import static android.content.Context.MODE_PRIVATE;
 import static android.content.Context.POWER_SERVICE;
 import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
-import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.TimeUnit.MINUTES;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 class AndroidTorPlugin extends TorPlugin {
 
 	// This tag may prevent Huawei's power manager from killing us
@@ -41,17 +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)
-				requireNonNull(appContext.getSystemService(POWER_SERVICE));
+				appContext.getSystemService(POWER_SERVICE);
+		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

@@ -1,8 +1,8 @@
 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;
@@ -25,15 +25,12 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.Immutable;
 import javax.net.SocketFactory;
 
-import static android.os.Build.VERSION.SDK_INT;
-import static java.util.logging.Logger.getLogger;
-
 @Immutable
 @NotNullByDefault
 public class AndroidTorPluginFactory implements DuplexPluginFactory {
 
 	private static final Logger LOG =
-			getLogger(AndroidTorPluginFactory.class.getName());
+			Logger.getLogger(AndroidTorPluginFactory.class.getName());
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
 	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
@@ -51,7 +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,
@@ -59,8 +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;
@@ -71,7 +66,6 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
-		this.batteryManager = batteryManager;
 		this.clock = clock;
 	}
 
@@ -104,14 +98,14 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			return null;
 		}
 		// Use position-independent executable for SDK >= 16
-		if (SDK_INT >= 16) architecture += "_pie";
+		if (Build.VERSION.SDK_INT >= 16) architecture += "_pie";
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				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/AndroidLocationUtils.java

@@ -15,13 +15,12 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import static android.content.Context.TELEPHONY_SERVICE;
-import static java.util.logging.Logger.getLogger;
 
 @NotNullByDefault
 class AndroidLocationUtils implements LocationUtils {
 
 	private static final Logger LOG =
-			getLogger(AndroidLocationUtils.class.getName());
+			Logger.getLogger(AndroidLocationUtils.class.getName());
 
 	private final Context appContext;
 
@@ -60,14 +59,14 @@ class AndroidLocationUtils implements LocationUtils {
 	}
 
 	private String getCountryFromPhoneNetwork() {
-		TelephonyManager tm = (TelephonyManager)
-				appContext.getSystemService(TELEPHONY_SERVICE);
-		return tm == null ? "" : tm.getNetworkCountryIso();
+		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
+		TelephonyManager tm = (TelephonyManager) o;
+		return tm.getNetworkCountryIso();
 	}
 
 	private String getCountryFromSimCard() {
-		TelephonyManager tm = (TelephonyManager)
-				appContext.getSystemService(TELEPHONY_SERVICE);
-		return tm == null ? "" : tm.getSimCountryIso();
+		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
+		TelephonyManager tm = (TelephonyManager) o;
+		return tm.getSimCountryIso();
 	}
 }

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;
@@ -8,6 +7,7 @@ import android.content.ContentResolver;
 import android.content.Context;
 import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiManager;
+import android.os.Build;
 import android.os.Parcel;
 import android.os.StrictMode;
 import android.provider.Settings;
@@ -22,14 +22,11 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static android.content.Context.WIFI_SERVICE;
-import static android.os.Build.FINGERPRINT;
-import static android.os.Build.SERIAL;
-import static android.os.Build.VERSION.SDK_INT;
 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;
 
@@ -40,27 +37,24 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		appContext = app.getApplicationContext();
 	}
 
-	@SuppressLint("HardwareIds")
 	@Override
 	protected void writeToEntropyPool(DataOutputStream out) throws IOException {
 		super.writeToEntropyPool(out);
 		out.writeInt(android.os.Process.myPid());
 		out.writeInt(android.os.Process.myTid());
 		out.writeInt(android.os.Process.myUid());
-		if (FINGERPRINT != null) out.writeUTF(FINGERPRINT);
-		if (SERIAL != null) out.writeUTF(SERIAL);
+		if (Build.FINGERPRINT != null) out.writeUTF(Build.FINGERPRINT);
+		if (Build.SERIAL != null) out.writeUTF(Build.SERIAL);
 		ContentResolver contentResolver = appContext.getContentResolver();
 		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) {
@@ -76,18 +70,20 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		// Silence strict mode
 		StrictMode.ThreadPolicy tp = StrictMode.allowThreadDiskWrites();
 		super.writeSeed();
-		if (SDK_INT >= 16 && SDK_INT <= 18) applyOpenSslFix();
+		if (Build.VERSION.SDK_INT >= 16 && Build.VERSION.SDK_INT <= 18)
+			applyOpenSslFix();
 		StrictMode.setThreadPolicy(tp);
 	}
 
 	// Based on https://android-developers.googleblog.com/2013/08/some-securerandom-thoughts.html
 	private void applyOpenSslFix() {
-		byte[] seed = new UnixSecureRandomSpi().engineGenerateSeed(SEED_LENGTH);
+		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

@@ -3,35 +3,36 @@ package org.briarproject.bramble.util;
 import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
+import android.os.Build;
 import android.provider.Settings;
 
 import java.io.File;
 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.CPU_ABI;
-import static android.os.Build.CPU_ABI2;
-import static android.os.Build.SUPPORTED_ABIS;
-import static android.os.Build.VERSION.SDK_INT;
-import static java.util.Arrays.asList;
-import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 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";
 
 	private static final String STORED_REPORTS = "dev-reports";
 
+	@SuppressWarnings("deprecation")
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
-		if (SDK_INT >= 21) {
-			abis.addAll(asList(SUPPORTED_ABIS));
+		if (Build.VERSION.SDK_INT >= 21) {
+			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
-			abis.add(CPU_ABI);
-			if (CPU_ABI2 != null) abis.add(CPU_ABI2);
+			abis.add(Build.CPU_ABI);
+			if (Build.CPU_ABI2 != null) abis.add(Build.CPU_ABI2);
 		}
 		return abis;
 	}
@@ -51,7 +52,7 @@ public class AndroidUtils {
 	}
 
 	private static boolean isValidBluetoothAddress(String address) {
-		return !isNullOrEmpty(address)
+		return !StringUtils.isNullOrEmpty(address)
 				&& BluetoothAdapter.checkBluetoothAddress(address)
 				&& !address.equals(FAKE_BLUETOOTH_ADDRESS);
 	}

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

@@ -10,19 +10,17 @@ import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
 
 @ThreadSafe
 @NotNullByDefault
 public class RenewableWakeLock {
 
 	private static final Logger LOG =
-			getLogger(RenewableWakeLock.class.getName());
+			Logger.getLogger(RenewableWakeLock.class.getName());
 
 	/**
 	 * Automatically release the lock this many milliseconds after it's due
@@ -38,12 +36,10 @@ public class RenewableWakeLock {
 	private final Runnable renewTask;
 
 	private final Object lock = new Object();
-	@GuardedBy("lock")
 	@Nullable
-	private PowerManager.WakeLock wakeLock;
-	@GuardedBy("lock")
+	private PowerManager.WakeLock wakeLock; // Locking: lock
 	@Nullable
-	private ScheduledFuture future;
+	private ScheduledFuture future; // Locking: lock
 
 	public RenewableWakeLock(PowerManager powerManager,
 			ScheduledExecutorService scheduler, int levelAndFlags, String tag,

bramble-android/witness.gradle

@@ -31,21 +31,16 @@ dependencyVerification {
         'com.android.tools:sdklib:26.2.1:sdklib-26.2.1.jar:248df7ad5eac4aeb6f96c394c76760de4b7b89ac056e54d0c21a739368b91b45',
         'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
         '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.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.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:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
         'com.google.guava:guava:23.0:guava-23.0.jar:7baa80df284117e5b945b19b98d367a85ea7b7801bd358ff657946c3bd1b6596',
-        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
         'com.google.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',
@@ -68,9 +63,7 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.7:obfs4proxy-android-0.0.7.zip:abdfb5d889d848de9bf214f9276abbf454808a505b870819eccc9a9e985bf617',
         'org.briarproject:tor-android:0.3.4.8:tor-android-0.3.4.8.zip:989a0352d9d8d8172cd6c2137654e165e5d2beb10ed1211bab3814e224ad1926',
-        'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
         'org.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',

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/Bytes.java

@@ -1,14 +1,13 @@
 package org.briarproject.bramble.api;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.util.Arrays;
 import java.util.Comparator;
 
 import javax.annotation.concurrent.ThreadSafe;
 
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-
 /**
  * A wrapper around a byte array, to allow it to be stored in maps etc.
  */
@@ -57,7 +56,8 @@ public class Bytes implements Comparable<Bytes> {
 
 	@Override
 	public String toString() {
-		return getClass().getSimpleName() + "(" + toHexString(getBytes()) + ")";
+		return getClass().getSimpleName() +
+				"(" + StringUtils.toHexString(getBytes()) + ")";
 	}
 
 	public static class BytesComparator implements Comparator<Bytes> {

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.api;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.NoSuchElementException;
@@ -9,8 +10,6 @@ import java.util.Set;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
-import static java.util.Collections.unmodifiableSet;
-
 @NotThreadSafe
 @NotNullByDefault
 public class Multiset<T> {
@@ -97,6 +96,6 @@ public class Multiset<T> {
 	 * is unmodifiable.
 	 */
 	public Set<T> keySet() {
-		return unmodifiableSet(map.keySet());
+		return Collections.unmodifiableSet(map.keySet());
 	}
 }

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/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/BdfMessageContext.java

@@ -5,11 +5,10 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 
 import java.util.Collection;
+import java.util.Collections;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.util.Collections.emptyList;
-
 @Immutable
 @NotNullByDefault
 public class BdfMessageContext {
@@ -24,7 +23,7 @@ public class BdfMessageContext {
 	}
 
 	public BdfMessageContext(BdfDictionary dictionary) {
-		this(dictionary, emptyList());
+		this(dictionary, Collections.emptyList());
 	}
 
 	public BdfDictionary getDictionary() {

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

@@ -9,14 +9,13 @@ 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;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.transport.TransportConstants.MAX_CLOCK_DIFFERENCE;
 
 @Immutable
@@ -24,7 +23,7 @@ import static org.briarproject.bramble.api.transport.TransportConstants.MAX_CLOC
 public abstract class BdfMessageValidator implements MessageValidator {
 
 	protected static final Logger LOG =
-			getLogger(BdfMessageValidator.class.getName());
+			Logger.getLogger(BdfMessageValidator.class.getName());
 
 	protected final ClientHelper clientHelper;
 	protected final MetadataEncoder metadataEncoder;

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

@@ -13,8 +13,6 @@ import java.util.Collection;
 
 import javax.annotation.Nullable;
 
-import static org.briarproject.bramble.api.contact.PendingContact.PendingContactState.FAILED;
-
 @NotNullByDefault
 public interface ContactManager {
 
@@ -54,35 +52,6 @@ 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.
 	 */
@@ -127,12 +96,6 @@ 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.
 	 */

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/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/BdfDictionary.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.FormatException;
 
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.TreeMap;
 
 import javax.annotation.Nullable;
@@ -23,9 +24,9 @@ public class BdfDictionary extends TreeMap<String, Object> {
 	 * );
 	 * </pre>
 	 */
-	public static BdfDictionary of(BdfEntry... entries) {
+	public static BdfDictionary of(Entry<String, ?>... entries) {
 		BdfDictionary d = new BdfDictionary();
-		for (BdfEntry e : entries) d.put(e.getKey(), e.getValue());
+		for (Entry<String, ?> e : entries) d.put(e.getKey(), e.getValue());
 		return d;
 	}
 

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

@@ -4,12 +4,12 @@ import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.FormatException;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
-import static java.util.Arrays.asList;
 import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
 
 @NotThreadSafe
@@ -22,7 +22,7 @@ public class BdfList extends ArrayList<Object> {
 	 * </pre>
 	 */
 	public static BdfList of(Object... items) {
-		return new BdfList(asList(items));
+		return new BdfList(Arrays.asList(items));
 	}
 
 	public BdfList() {
@@ -33,7 +33,6 @@ public class BdfList extends ArrayList<Object> {
 		super(items);
 	}
 
-	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
 	private boolean isInRange(int index) {
 		return index >= 0 && index < size();
 	}

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.
@@ -88,14 +89,6 @@ public interface DatabaseComponent {
 	<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 +366,12 @@ 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 +380,15 @@ 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
@@ -543,7 +535,7 @@ 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

@@ -1,8 +1,5 @@
 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

@@ -1,8 +1,5 @@
 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/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/db/Transaction.java

@@ -3,12 +3,11 @@ package org.briarproject.bramble.api.db;
 import org.briarproject.bramble.api.event.Event;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
-import static java.util.Collections.emptyList;
-
 /**
  * A wrapper around a database transaction. Transactions are not thread-safe.
  */
@@ -54,7 +53,7 @@ public class Transaction {
 	 * Returns any events attached to the transaction.
 	 */
 	public List<Event> getEvents() {
-		if (events == null) return emptyList();
+		if (events == null) return Collections.emptyList();
 		return events;
 	}
 

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

@@ -2,12 +2,12 @@ package org.briarproject.bramble.api.identity;
 
 import org.briarproject.bramble.api.Nameable;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 /**
  * A pseudonym for a user.
@@ -28,7 +28,7 @@ public class Author implements Nameable {
 
 	public Author(AuthorId id, int formatVersion, String name,
 			byte[] publicKey) {
-		int nameLength = toUtf8(name).length;
+		int nameLength = StringUtils.toUtf8(name).length;
 		if (nameLength == 0 || nameLength > MAX_AUTHOR_NAME_LENGTH)
 			throw new IllegalArgumentException();
 		if (publicKey.length == 0 || publicKey.length > MAX_PUBLIC_KEY_LENGTH)

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

@@ -39,18 +39,4 @@ public class AuthorInfo {
 		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/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

@@ -16,7 +16,6 @@ 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/plugin/TransportId.java

@@ -1,6 +1,6 @@
 package org.briarproject.bramble.api.plugin;
 
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
+import org.briarproject.bramble.util.StringUtils;
 
 /**
  * Type-safe wrapper for a namespaced string that uniquely identifies a
@@ -11,12 +11,12 @@ public class TransportId {
 	/**
 	 * The maximum length of a transport identifier in UTF-8 bytes.
 	 */
-	public static final int MAX_TRANSPORT_ID_LENGTH = 100;
+	public static int MAX_TRANSPORT_ID_LENGTH = 100;
 
 	private final String id;
 
 	public TransportId(String id) {
-		int length = toUtf8(id).length;
+		int length = StringUtils.toUtf8(id).length;
 		if (length == 0 || length > MAX_TRANSPORT_ID_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;

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

@@ -1,11 +1,10 @@
 package org.briarproject.bramble.api.sync;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
-
 /**
  * Type-safe wrapper for a namespaced string that uniquely identifies a sync
  * client.
@@ -17,12 +16,12 @@ public class ClientId implements Comparable<ClientId> {
 	/**
 	 * The maximum length of a client identifier in UTF-8 bytes.
 	 */
-	public static final int MAX_CLIENT_ID_LENGTH = 100;
+	public static int MAX_CLIENT_ID_LENGTH = 100;
 
 	private final String id;
 
 	public ClientId(String id) {
-		int length = toUtf8(id).length;
+		int length = StringUtils.toUtf8(id).length;
 		if (length == 0 || length > MAX_CLIENT_ID_LENGTH)
 			throw new IllegalArgumentException();
 		this.id = id;

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

@@ -4,11 +4,10 @@ import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
+import java.util.Collections;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.util.Collections.emptyList;
-
 @Immutable
 @NotNullByDefault
 public class MessageContext {
@@ -23,7 +22,7 @@ public class MessageContext {
 	}
 
 	public MessageContext(Metadata metadata) {
-		this(metadata, emptyList());
+		this(metadata, Collections.emptyList());
 	}
 
 	public Metadata getMetadata() {

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

@@ -8,21 +8,17 @@ 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 java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 public class IoUtils {
 
-	private static final Logger LOG = getLogger(IoUtils.class.getName());
+	private static final Logger LOG = Logger.getLogger(IoUtils.class.getName());
 
 	public static void deleteFileOrDir(File f) {
 		if (f.isFile()) {
@@ -58,35 +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);
 		}
 	}
 

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

@@ -7,15 +7,13 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
 
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
-
 @NotNullByDefault
 public class ValidationUtils {
 
 	public static void checkLength(@Nullable String s, int minLength,
 			int maxLength) throws FormatException {
 		if (s != null) {
-			int length = toUtf8(s).length;
+			int length = StringUtils.toUtf8(s).length;
 			if (length < minLength) throw new FormatException();
 			if (length > maxLength) throw new FormatException();
 		}
@@ -23,7 +21,7 @@ public class ValidationUtils {
 
 	public static void checkLength(@Nullable String s, int length)
 			throws FormatException {
-		if (s != null && toUtf8(s).length != length)
+		if (s != null && StringUtils.toUtf8(s).length != length)
 			throw new FormatException();
 	}
 

bramble-api/src/test/java/org/briarproject/bramble/api/data/BdfDictionaryTest.java

@@ -8,7 +8,6 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map.Entry;
 
-import static java.util.Collections.singletonMap;
 import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -20,15 +19,15 @@ public class BdfDictionaryTest extends BrambleTestCase {
 	public void testConstructors() {
 		assertEquals(Collections.<String, Object>emptyMap(),
 				new BdfDictionary());
-		assertEquals(singletonMap("foo", NULL_VALUE),
-				new BdfDictionary(singletonMap("foo", NULL_VALUE)));
+		assertEquals(Collections.singletonMap("foo", NULL_VALUE),
+				new BdfDictionary(Collections.singletonMap("foo", NULL_VALUE)));
 	}
 
 	@Test
 	public void testFactoryMethod() {
 		assertEquals(Collections.<String, Object>emptyMap(),
 				BdfDictionary.of());
-		assertEquals(singletonMap("foo", NULL_VALUE),
+		assertEquals(Collections.singletonMap("foo", NULL_VALUE),
 				BdfDictionary.of(new BdfEntry("foo", NULL_VALUE)));
 	}
 
@@ -68,7 +67,7 @@ public class BdfDictionaryTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testKeySetIteratorIsOrderedByKeys() {
+	public void testKeySetIteratorIsOrderedByKeys() throws Exception {
 		BdfDictionary d = new BdfDictionary();
 		d.put("a", 1);
 		d.put("d", 4);
@@ -87,7 +86,7 @@ public class BdfDictionaryTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testValuesIteratorIsOrderedByKeys() {
+	public void testValuesIteratorIsOrderedByKeys() throws Exception {
 		BdfDictionary d = new BdfDictionary();
 		d.put("a", 1);
 		d.put("d", 4);
@@ -106,7 +105,7 @@ public class BdfDictionaryTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testEntrySetIteratorIsOrderedByKeys() {
+	public void testEntrySetIteratorIsOrderedByKeys() throws Exception {
 		BdfDictionary d = new BdfDictionary();
 		d.put("a", 1);
 		d.put("d", 4);

bramble-api/src/test/java/org/briarproject/bramble/api/data/BdfListTest.java

@@ -5,31 +5,26 @@ import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.junit.Test;
 
-import java.util.Random;
+import java.util.Arrays;
+import java.util.Collections;
 
-import static java.util.Arrays.asList;
-import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
-import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
-import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 
 public class BdfListTest extends BrambleTestCase {
 
-	private final Random random = new Random();
-
 	@Test
 	public void testConstructors() {
-		assertEquals(emptyList(), new BdfList());
-		assertEquals(asList(1, 2, NULL_VALUE),
-				new BdfList(asList(1, 2, NULL_VALUE)));
+		assertEquals(Collections.emptyList(), new BdfList());
+		assertEquals(Arrays.asList(1, 2, NULL_VALUE),
+				new BdfList(Arrays.asList(1, 2, NULL_VALUE)));
 	}
 
 	@Test
 	public void testFactoryMethod() {
-		assertEquals(emptyList(), BdfList.of());
-		assertEquals(asList(1, 2, NULL_VALUE),
+		assertEquals(Collections.emptyList(), BdfList.of());
+		assertEquals(Arrays.asList(1, 2, NULL_VALUE),
 				BdfList.of(1, 2, NULL_VALUE));
 	}
 
@@ -69,21 +64,22 @@ public class BdfListTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testIndexOutOfBoundsReturnsDefaultValue() {
+	@SuppressWarnings("ConstantConditions")
+	public void testIndexOutOfBoundsReturnsDefaultValue() throws Exception {
 		BdfList list = BdfList.of(1, 2, 3);
-		boolean defaultBoolean = random.nextBoolean();
+		boolean defaultBoolean = true;
 		assertEquals(defaultBoolean, list.getBoolean(-1, defaultBoolean));
 		assertEquals(defaultBoolean, list.getBoolean(3, defaultBoolean));
-		Long defaultLong = random.nextLong();
+		Long defaultLong = 123L;
 		assertEquals(defaultLong, list.getLong(-1, defaultLong));
 		assertEquals(defaultLong, list.getLong(3, defaultLong));
-		Double defaultDouble = random.nextDouble();
+		Double defaultDouble = 1.23;
 		assertEquals(defaultDouble, list.getDouble(-1, defaultDouble));
 		assertEquals(defaultDouble, list.getDouble(3, defaultDouble));
-		String defaultString = getRandomString(123);
+		String defaultString = "123";
 		assertEquals(defaultString, list.getString(-1, defaultString));
 		assertEquals(defaultString, list.getString(3, defaultString));
-		byte[] defaultBytes = getRandomBytes(123);
+		byte[] defaultBytes = new byte[] {1, 2, 3};
 		assertArrayEquals(defaultBytes, list.getRaw(-1, defaultBytes));
 		assertArrayEquals(defaultBytes, list.getRaw(3, defaultBytes));
 		BdfList defaultList = BdfList.of(1, 2, 3);
@@ -99,17 +95,18 @@ public class BdfListTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testWrongTypeReturnsDefaultValue() {
+	@SuppressWarnings("ConstantConditions")
+	public void testWrongTypeReturnsDefaultValue() throws Exception {
 		BdfList list = BdfList.of(1, 2, 3, true);
-		boolean defaultBoolean = random.nextBoolean();
+		boolean defaultBoolean = true;
 		assertEquals(defaultBoolean, list.getBoolean(0, defaultBoolean));
-		Long defaultLong = random.nextLong();
+		Long defaultLong = 123L;
 		assertEquals(defaultLong, list.getLong(3, defaultLong));
-		Double defaultDouble = random.nextDouble();
+		Double defaultDouble = 1.23;
 		assertEquals(defaultDouble, list.getDouble(0, defaultDouble));
-		String defaultString = getRandomString(123);
+		String defaultString = "123";
 		assertEquals(defaultString, list.getString(0, defaultString));
-		byte[] defaultBytes = getRandomBytes(123);
+		byte[] defaultBytes = new byte[] {1, 2, 3};
 		assertArrayEquals(defaultBytes, list.getRaw(0, defaultBytes));
 		BdfList defaultList = BdfList.of(1, 2, 3);
 		assertEquals(defaultList, list.getList(0, defaultList));

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/TestUtils.java

@@ -12,10 +12,12 @@ import org.briarproject.bramble.api.sync.Group;
 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.util.IoUtils;
 
 import java.io.File;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -23,7 +25,6 @@ import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static java.util.Arrays.asList;
-import static java.util.Collections.sort;
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
@@ -32,7 +33,6 @@ import static org.briarproject.bramble.api.properties.TransportPropertyConstants
 import static org.briarproject.bramble.api.sync.ClientId.MAX_CLIENT_ID_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
-import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
 
 public class TestUtils {
@@ -48,10 +48,8 @@ public class TestUtils {
 	}
 
 	public static void deleteTestDirectory(File testDir) {
-		deleteFileOrDir(testDir);
-		// Delete parent directory only if it's empty
-		//noinspection ResultOfMethodCallIgnored
-		testDir.getParentFile().delete();
+		IoUtils.deleteFileOrDir(testDir);
+		testDir.getParentFile().delete(); // Delete if empty
 	}
 
 	public static byte[] getRandomBytes(int length) {
@@ -147,7 +145,7 @@ public class TestUtils {
 		if (size == 0) throw new IllegalArgumentException();
 		List<Double> sorted = new ArrayList<>(size);
 		for (Number n : samples) sorted.add(n.doubleValue());
-		sort(sorted);
+		Collections.sort(sorted);
 		if (size % 2 == 1) return sorted.get(size / 2);
 		double low = sorted.get(size / 2 - 1), high = sorted.get(size / 2);
 		return (low + high) / 2;

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')
@@ -17,7 +17,7 @@ dependencies {
 	implementation 'org.whispersystems:curve25519-java:0.5.0'
 	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/PoliteExecutor.java

@@ -10,7 +10,6 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.GuardedBy;
 
 import static java.util.logging.Level.FINE;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 /**
@@ -43,7 +42,7 @@ public class PoliteExecutor implements Executor {
 			int maxConcurrentTasks) {
 		this.delegate = delegate;
 		this.maxConcurrentTasks = maxConcurrentTasks;
-		log = getLogger(tag);
+		log = Logger.getLogger(tag);
 	}
 
 	@Override

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

@@ -9,7 +9,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.FINE;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
@@ -23,7 +22,7 @@ public class TimeLoggingExecutor extends ThreadPoolExecutor {
 			RejectedExecutionHandler handler) {
 		super(corePoolSize, maxPoolSize, keepAliveTime, unit, workQueue,
 				handler);
-		log = getLogger(tag);
+		log = Logger.getLogger(tag);
 	}
 
 	@Override

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

@@ -6,7 +6,9 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 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.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.util.IoUtils;
 
 import java.io.BufferedReader;
 import java.io.File;
@@ -17,21 +19,19 @@ import java.io.InputStreamReader;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.fromHexString;
 import static org.briarproject.bramble.util.StringUtils.toHexString;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 class AccountManagerImpl implements AccountManager {
 
 	private static final Logger LOG =
-			getLogger(AccountManagerImpl.class.getName());
+			Logger.getLogger(AccountManagerImpl.class.getName());
 
 	private static final String DB_KEY_FILENAME = "db.key";
 	private static final String DB_KEY_BACKUP_FILENAME = "db.key.bak";
@@ -68,7 +68,7 @@ class AccountManagerImpl implements AccountManager {
 		return databaseKey;
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	@Nullable
 	protected String loadEncryptedDatabaseKey() {
 		String key = readDbKeyFromFile(dbKeyFile);
@@ -83,7 +83,7 @@ class AccountManagerImpl implements AccountManager {
 		return key;
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	@Nullable
 	private String readDbKeyFromFile(File f) {
 		if (!f.exists()) {
@@ -102,8 +102,8 @@ class AccountManagerImpl implements AccountManager {
 		}
 	}
 
-	@GuardedBy("stateChangeLock")
-	boolean storeEncryptedDatabaseKey(String hex) {
+	// Locking: stateChangeLock
+	protected boolean storeEncryptedDatabaseKey(String hex) {
 		LOG.info("Storing database key in file");
 		// Create the directory if necessary
 		if (databaseConfig.getDatabaseKeyDirectory().mkdirs())
@@ -140,7 +140,7 @@ class AccountManagerImpl implements AccountManager {
 		}
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	private void writeDbKeyToFile(String key, File f) throws IOException {
 		FileOutputStream out = new FileOutputStream(f);
 		out.write(key.getBytes("UTF-8"));
@@ -170,7 +170,7 @@ class AccountManagerImpl implements AccountManager {
 		}
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	private boolean encryptAndStoreDatabaseKey(SecretKey key, String password) {
 		byte[] plaintext = key.getBytes();
 		byte[] ciphertext = crypto.encryptWithPassword(plaintext, password);
@@ -181,8 +181,8 @@ class AccountManagerImpl implements AccountManager {
 	public void deleteAccount() {
 		synchronized (stateChangeLock) {
 			LOG.info("Deleting account");
-			deleteFileOrDir(databaseConfig.getDatabaseKeyDirectory());
-			deleteFileOrDir(databaseConfig.getDatabaseDirectory());
+			IoUtils.deleteFileOrDir(databaseConfig.getDatabaseKeyDirectory());
+			IoUtils.deleteFileOrDir(databaseConfig.getDatabaseDirectory());
 			databaseKey = null;
 		}
 	}
@@ -197,7 +197,7 @@ class AccountManagerImpl implements AccountManager {
 		}
 	}
 
-	@GuardedBy("stateChangeLock")
+	// Locking: stateChangeLock
 	@Nullable
 	private SecretKey loadAndDecryptDatabaseKey(String password) {
 		String hex = loadEncryptedDatabaseKey();

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

@@ -13,6 +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.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -43,7 +44,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.contact.RecordTypes.CONTACT_INFO;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -55,7 +55,7 @@ import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 
 	private static final Logger LOG =
-			getLogger(ContactExchangeTaskImpl.class.getName());
+			Logger.getLogger(ContactExchangeTaskImpl.class.getName());
 
 	private static final String SIGNING_LABEL_EXCHANGE =
 			"org.briarproject.briar.contact/EXCHANGE";
@@ -158,8 +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,
@@ -191,7 +190,6 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			streamWriter.sendEndOfStream();
 			// Skip any remaining records from the incoming stream
 			try {
-				//noinspection InfiniteLoopStatement
 				while (true) recordReader.readRecord();
 			} catch (EOFException expected) {
 				LOG.info("End of stream");
@@ -289,14 +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;
@@ -21,16 +19,12 @@ 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;
@@ -42,12 +36,6 @@ import static org.briarproject.bramble.util.StringUtils.toUtf8;
 @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;
@@ -91,63 +79,42 @@ 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 +132,14 @@ 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 +147,13 @@ 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
@@ -184,20 +163,14 @@ class ContactManagerImpl implements ContactManager {
 	}
 
 	@Override
-	public void setContactAlias(Transaction txn, ContactId c,
-			@Nullable String alias) throws DbException {
+	public void setContactAlias(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));
+		db.transaction(false, txn -> db.setContactAlias(txn, c, alias));
 	}
 
 	@Override
@@ -209,8 +182,15 @@ 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

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

@@ -2,20 +2,18 @@ package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import static org.briarproject.bramble.util.StringUtils.fromHexString;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
+import org.briarproject.bramble.util.StringUtils;
 
 @NotNullByDefault
 class AsciiArmour {
 
 	static String wrap(byte[] b, int lineLength) {
-		String wrapped = toHexString(b);
+		String wrapped = StringUtils.toHexString(b);
 		StringBuilder s = new StringBuilder();
 		int length = wrapped.length();
 		for (int i = 0; i < length; i += lineLength) {
 			int end = Math.min(i + lineLength, length);
-			s.append(wrapped, i, end);
+			s.append(wrapped.substring(i, end));
 			s.append("\r\n");
 		}
 		return s.toString();
@@ -23,7 +21,7 @@ class AsciiArmour {
 
 	static byte[] unwrap(String s) throws FormatException {
 		try {
-			return fromHexString(s.replaceAll("[^0-9a-fA-F]", ""));
+			return StringUtils.fromHexString(s.replaceAll("[^0-9a-fA-F]", ""));
 		} catch (IllegalArgumentException e) {
 			throw new FormatException();
 		}

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

@@ -12,6 +12,8 @@ import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
+import org.briarproject.bramble.util.ByteUtils;
+import org.briarproject.bramble.util.StringUtils;
 import org.spongycastle.crypto.CryptoException;
 import org.spongycastle.crypto.Digest;
 import org.spongycastle.crypto.digests.Blake2bDigest;
@@ -28,21 +30,16 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static java.lang.System.arraycopy;
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.readUint32;
-import static org.briarproject.bramble.util.ByteUtils.writeUint32;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 @NotNullByDefault
 class CryptoComponentImpl implements CryptoComponent {
 
 	private static final Logger LOG =
-			getLogger(CryptoComponentImpl.class.getName());
+			Logger.getLogger(CryptoComponentImpl.class.getName());
 
 	private static final int SIGNATURE_KEY_PAIR_BITS = 256;
 	private static final int STORAGE_IV_BYTES = 24; // 196 bits
@@ -191,7 +188,7 @@ class CryptoComponentImpl implements CryptoComponent {
 		PrivateKey ourPriv = ourKeyPair.getPrivate();
 		byte[][] hashInputs = new byte[inputs.length + 1][];
 		hashInputs[0] = performRawKeyAgreement(ourPriv, theirPublicKey);
-		arraycopy(inputs, 0, hashInputs, 1, inputs.length);
+		System.arraycopy(inputs, 0, hashInputs, 1, inputs.length);
 		byte[] hash = hash(label, hashInputs);
 		if (hash.length != SecretKey.LENGTH) throw new IllegalStateException();
 		return new SecretKey(hash);
@@ -219,26 +216,26 @@ class CryptoComponentImpl implements CryptoComponent {
 
 	private void updateSignature(Signature signature, String label,
 			byte[] toSign) throws GeneralSecurityException {
-		byte[] labelBytes = toUtf8(label);
+		byte[] labelBytes = StringUtils.toUtf8(label);
 		byte[] length = new byte[INT_32_BYTES];
-		writeUint32(labelBytes.length, length, 0);
+		ByteUtils.writeUint32(labelBytes.length, length, 0);
 		signature.update(length);
 		signature.update(labelBytes);
-		writeUint32(toSign.length, length, 0);
+		ByteUtils.writeUint32(toSign.length, length, 0);
 		signature.update(length);
 		signature.update(toSign);
 	}
 
 	@Override
 	public byte[] hash(String label, byte[]... inputs) {
-		byte[] labelBytes = toUtf8(label);
+		byte[] labelBytes = StringUtils.toUtf8(label);
 		Digest digest = new Blake2bDigest(256);
 		byte[] length = new byte[INT_32_BYTES];
-		writeUint32(labelBytes.length, length, 0);
+		ByteUtils.writeUint32(labelBytes.length, length, 0);
 		digest.update(length, 0, length.length);
 		digest.update(labelBytes, 0, labelBytes.length);
 		for (byte[] input : inputs) {
-			writeUint32(input.length, length, 0);
+			ByteUtils.writeUint32(input.length, length, 0);
 			digest.update(length, 0, length.length);
 			digest.update(input, 0, input.length);
 		}
@@ -249,14 +246,14 @@ class CryptoComponentImpl implements CryptoComponent {
 
 	@Override
 	public byte[] mac(String label, SecretKey macKey, byte[]... inputs) {
-		byte[] labelBytes = toUtf8(label);
+		byte[] labelBytes = StringUtils.toUtf8(label);
 		Digest mac = new Blake2bDigest(macKey.getBytes(), 32, null, null);
 		byte[] length = new byte[INT_32_BYTES];
-		writeUint32(labelBytes.length, length, 0);
+		ByteUtils.writeUint32(labelBytes.length, length, 0);
 		mac.update(length, 0, length.length);
 		mac.update(labelBytes, 0, labelBytes.length);
 		for (byte[] input : inputs) {
-			writeUint32(input.length, length, 0);
+			ByteUtils.writeUint32(input.length, length, 0);
 			mac.update(length, 0, length.length);
 			mac.update(input, 0, input.length);
 		}
@@ -300,13 +297,13 @@ class CryptoComponentImpl implements CryptoComponent {
 		output[outputOff] = PBKDF_FORMAT_SCRYPT;
 		outputOff++;
 		// Salt
-		arraycopy(salt, 0, output, outputOff, salt.length);
+		System.arraycopy(salt, 0, output, outputOff, salt.length);
 		outputOff += salt.length;
 		// Cost parameter
-		writeUint32(cost, output, outputOff);
+		ByteUtils.writeUint32(cost, output, outputOff);
 		outputOff += INT_32_BYTES;
 		// IV
-		arraycopy(iv, 0, output, outputOff, iv.length);
+		System.arraycopy(iv, 0, output, outputOff, iv.length);
 		outputOff += iv.length;
 		// Initialise the cipher and encrypt the plaintext
 		try {
@@ -336,16 +333,16 @@ class CryptoComponentImpl implements CryptoComponent {
 			return null; // Unknown format
 		// Salt
 		byte[] salt = new byte[PBKDF_SALT_BYTES];
-		arraycopy(input, inputOff, salt, 0, salt.length);
+		System.arraycopy(input, inputOff, salt, 0, salt.length);
 		inputOff += salt.length;
 		// Cost parameter
-		long cost = readUint32(input, inputOff);
+		long cost = ByteUtils.readUint32(input, inputOff);
 		inputOff += INT_32_BYTES;
 		if (cost < 2 || cost > Integer.MAX_VALUE)
 			return null; // Invalid cost parameter
 		// IV
 		byte[] iv = new byte[STORAGE_IV_BYTES];
-		arraycopy(input, inputOff, iv, 0, iv.length);
+		System.arraycopy(input, inputOff, iv, 0, iv.length);
 		inputOff += iv.length;
 		// Derive the key from the password
 		SecretKey key = passwordBasedKdf.deriveKey(password, salt, (int) cost);

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

@@ -7,8 +7,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
 
-import static java.lang.System.arraycopy;
-
 @NotNullByDefault
 class Curve25519KeyParser implements KeyParser {
 
@@ -28,7 +26,7 @@ class Curve25519KeyParser implements KeyParser {
 
 	static byte[] clamp(byte[] b) {
 		byte[] clamped = new byte[32];
-		arraycopy(b, 0, clamped, 0, 32);
+		System.arraycopy(b, 0, clamped, 0, 32);
 		clamped[0] &= 248;
 		clamped[31] &= 127;
 		clamped[31] |= 64;

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

@@ -1,15 +1,13 @@
 package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.ByteUtils;
 
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_HEADER_PLAINTEXT_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_NONCE_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.MAX_PAYLOAD_LENGTH;
 import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.readUint16;
-import static org.briarproject.bramble.util.ByteUtils.writeUint16;
-import static org.briarproject.bramble.util.ByteUtils.writeUint64;
 
 @NotNullByDefault
 class FrameEncoder {
@@ -18,7 +16,7 @@ class FrameEncoder {
 		if (dest.length < FRAME_NONCE_LENGTH)
 			throw new IllegalArgumentException();
 		if (frameNumber < 0) throw new IllegalArgumentException();
-		writeUint64(frameNumber, dest, 0);
+		ByteUtils.writeUint64(frameNumber, dest, 0);
 		if (header) dest[0] |= 0x80;
 		for (int i = INT_64_BYTES; i < FRAME_NONCE_LENGTH; i++) dest[i] = 0;
 	}
@@ -31,8 +29,8 @@ class FrameEncoder {
 		if (paddingLength < 0) throw new IllegalArgumentException();
 		if (payloadLength + paddingLength > MAX_PAYLOAD_LENGTH)
 			throw new IllegalArgumentException();
-		writeUint16(payloadLength, dest, 0);
-		writeUint16(paddingLength, dest, INT_16_BYTES);
+		ByteUtils.writeUint16(payloadLength, dest, 0);
+		ByteUtils.writeUint16(paddingLength, dest, INT_16_BYTES);
 		if (finalFrame) dest[0] |= 0x80;
 	}
 
@@ -45,12 +43,12 @@ class FrameEncoder {
 	static int getPayloadLength(byte[] header) {
 		if (header.length < FRAME_HEADER_PLAINTEXT_LENGTH)
 			throw new IllegalArgumentException();
-		return readUint16(header, 0) & 0x7FFF;
+		return ByteUtils.readUint16(header, 0) & 0x7FFF;
 	}
 
 	static int getPaddingLength(byte[] header) {
 		if (header.length < FRAME_HEADER_PLAINTEXT_LENGTH)
 			throw new IllegalArgumentException();
-		return readUint16(header, INT_16_BYTES);
+		return ByteUtils.readUint16(header, INT_16_BYTES);
 	}
 }

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

@@ -8,7 +8,6 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 
 import javax.inject.Inject;
 
-import static java.lang.System.arraycopy;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
 
 class KeyAgreementCryptoImpl implements KeyAgreementCrypto {
@@ -25,7 +24,7 @@ class KeyAgreementCryptoImpl implements KeyAgreementCrypto {
 		byte[] hash = crypto.hash(COMMIT_LABEL, publicKey.getEncoded());
 		// The output is the first COMMIT_LENGTH bytes of the hash
 		byte[] commitment = new byte[COMMIT_LENGTH];
-		arraycopy(hash, 0, commitment, 0, COMMIT_LENGTH);
+		System.arraycopy(hash, 0, commitment, 0, COMMIT_LENGTH);
 		return commitment;
 	}
 

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.StringUtils;
 import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
 import org.spongycastle.asn1.x9.X9ECParameters;
 import org.spongycastle.crypto.AsymmetricCipherKeyPair;
@@ -44,9 +45,6 @@ import java.util.Scanner;
 
 import javax.annotation.concurrent.Immutable;
 
-import static org.briarproject.bramble.util.StringUtils.fromHexString;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-
 @Immutable
 @NotNullByDefault
 public class MessageEncrypter {
@@ -159,7 +157,6 @@ public class MessageEncrypter {
 			printUsage();
 			System.exit(1);
 		}
-		//noinspection IfCanBeSwitch
 		if (args[0].equals("generate")) {
 			if (args.length != 3) {
 				printUsage();
@@ -213,11 +210,11 @@ public class MessageEncrypter {
 		MessageEncrypter encrypter = new MessageEncrypter(random);
 		KeyPair keyPair = encrypter.generateKeyPair();
 		PrintStream out = new PrintStream(new FileOutputStream(publicKeyFile));
-		out.print(toHexString(keyPair.getPublic().getEncoded()));
+		out.print(StringUtils.toHexString(keyPair.getPublic().getEncoded()));
 		out.flush();
 		out.close();
 		out = new PrintStream(new FileOutputStream(privateKeyFile));
-		out.print(toHexString(keyPair.getPrivate().getEncoded()));
+		out.print(StringUtils.toHexString(keyPair.getPrivate().getEncoded()));
 		out.flush();
 		out.close();
 	}
@@ -226,7 +223,7 @@ public class MessageEncrypter {
 		SecureRandom random = new SecureRandom();
 		MessageEncrypter encrypter = new MessageEncrypter(random);
 		InputStream in = new FileInputStream(publicKeyFile);
-		byte[] keyBytes = fromHexString(readFully(in).trim());
+		byte[] keyBytes = StringUtils.fromHexString(readFully(in).trim());
 		PublicKey publicKey =
 				encrypter.getKeyParser().parsePublicKey(keyBytes);
 		String message = readFully(System.in);
@@ -239,7 +236,7 @@ public class MessageEncrypter {
 		SecureRandom random = new SecureRandom();
 		MessageEncrypter encrypter = new MessageEncrypter(random);
 		InputStream in = new FileInputStream(privateKeyFile);
-		byte[] keyBytes = fromHexString(readFully(in).trim());
+		byte[] keyBytes = StringUtils.fromHexString(readFully(in).trim());
 		PrivateKey privateKey =
 				encrypter.getKeyParser().parsePrivateKey(keyBytes);
 		byte[] ciphertext = AsciiArmour.unwrap(readFully(System.in));

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.StringUtils;
 import org.spongycastle.crypto.generators.SCrypt;
 
 import java.util.logging.Logger;
@@ -9,14 +10,13 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 class ScryptKdf implements PasswordBasedKdf {
 
-	private static final Logger LOG = getLogger(ScryptKdf.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(ScryptKdf.class.getName());
 
 	private static final int MIN_COST = 256; // Min parameter N
 	private static final int MAX_COST = 1024 * 1024; // Max parameter N
@@ -53,7 +53,7 @@ class ScryptKdf implements PasswordBasedKdf {
 	@Override
 	public SecretKey deriveKey(String password, byte[] salt, int cost) {
 		long start = now();
-		byte[] passwordBytes = toUtf8(password);
+		byte[] passwordBytes = StringUtils.toUtf8(password);
 		SecretKey k = new SecretKey(SCrypt.generate(passwordBytes, salt, cost,
 				BLOCK_SIZE, PARALLELIZATION, SecretKey.LENGTH));
 		logDuration(LOG, "Deriving key from password", start);

bramble-core/src/main/java/org/briarproject/bramble/crypto/Sec1KeyParser.java

@@ -16,8 +16,6 @@ import java.util.logging.Logger;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.lang.System.arraycopy;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
 
@@ -30,7 +28,8 @@ import static org.briarproject.bramble.util.LogUtils.now;
 @NotNullByDefault
 class Sec1KeyParser implements KeyParser {
 
-	private static final Logger LOG = getLogger(Sec1KeyParser.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(Sec1KeyParser.class.getName());
 
 	private final ECDomainParameters params;
 	private final BigInteger modulus;
@@ -57,12 +56,12 @@ class Sec1KeyParser implements KeyParser {
 		if (encodedKey[0] != 4) throw new GeneralSecurityException();
 		// The x co-ordinate must be >= 0 and < p
 		byte[] xBytes = new byte[bytesPerInt];
-		arraycopy(encodedKey, 1, xBytes, 0, bytesPerInt);
+		System.arraycopy(encodedKey, 1, xBytes, 0, bytesPerInt);
 		BigInteger x = new BigInteger(1, xBytes); // Positive signum
 		if (x.compareTo(modulus) >= 0) throw new GeneralSecurityException();
 		// The y co-ordinate must be >= 0 and < p
 		byte[] yBytes = new byte[bytesPerInt];
-		arraycopy(encodedKey, 1 + bytesPerInt, yBytes, 0, bytesPerInt);
+		System.arraycopy(encodedKey, 1 + bytesPerInt, yBytes, 0, bytesPerInt);
 		BigInteger y = new BigInteger(1, yBytes); // Positive signum
 		if (y.compareTo(modulus) >= 0) throw new GeneralSecurityException();
 		// Verify that y^2 == x^3 + ax + b (mod p)

bramble-core/src/main/java/org/briarproject/bramble/crypto/Sec1Utils.java

@@ -2,8 +2,6 @@ package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
-import static java.lang.System.arraycopy;
-
 @NotNullByDefault
 class Sec1Utils {
 
@@ -12,10 +10,10 @@ class Sec1Utils {
 		if (src.length < destLen) {
 			int padding = destLen - src.length;
 			for (int i = destOff; i < destOff + padding; i++) dest[i] = 0;
-			arraycopy(src, 0, dest, destOff + padding, src.length);
+			System.arraycopy(src, 0, dest, destOff + padding, src.length);
 		} else {
 			int srcOff = src.length - destLen;
-			arraycopy(src, srcOff, dest, destOff, destLen);
+			System.arraycopy(src, srcOff, dest, destOff, destLen);
 		}
 	}
 }

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamDecrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.ByteUtils;
 
 import java.io.EOFException;
 import java.io.IOException;
@@ -13,7 +14,6 @@ import java.security.GeneralSecurityException;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
-import static java.lang.System.arraycopy;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_HEADER_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_HEADER_PLAINTEXT_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_NONCE_LENGTH;
@@ -26,8 +26,6 @@ import static org.briarproject.bramble.api.transport.TransportConstants.STREAM_H
 import static org.briarproject.bramble.api.transport.TransportConstants.STREAM_HEADER_PLAINTEXT_LENGTH;
 import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.readUint16;
-import static org.briarproject.bramble.util.ByteUtils.readUint64;
 
 @NotThreadSafe
 @NotNullByDefault
@@ -132,7 +130,7 @@ class StreamDecrypterImpl implements StreamDecrypter {
 		}
 		// Extract the nonce
 		byte[] streamHeaderNonce = new byte[STREAM_HEADER_NONCE_LENGTH];
-		arraycopy(streamHeaderCiphertext, 0, streamHeaderNonce, 0,
+		System.arraycopy(streamHeaderCiphertext, 0, streamHeaderNonce, 0,
 				STREAM_HEADER_NONCE_LENGTH);
 		// Decrypt and authenticate the stream header
 		try {
@@ -147,16 +145,17 @@ class StreamDecrypterImpl implements StreamDecrypter {
 			throw new FormatException();
 		}
 		// Check the protocol version
-		int receivedProtocolVersion = readUint16(streamHeaderPlaintext, 0);
+		int receivedProtocolVersion =
+				ByteUtils.readUint16(streamHeaderPlaintext, 0);
 		if (receivedProtocolVersion != PROTOCOL_VERSION)
 			throw new FormatException();
 		// Check the stream number
-		long receivedStreamNumber = readUint64(streamHeaderPlaintext,
+		long receivedStreamNumber = ByteUtils.readUint64(streamHeaderPlaintext,
 				INT_16_BYTES);
 		if (receivedStreamNumber != streamNumber) throw new FormatException();
 		// Extract the frame key
 		byte[] frameKeyBytes = new byte[SecretKey.LENGTH];
-		arraycopy(streamHeaderPlaintext, INT_16_BYTES + INT_64_BYTES,
+		System.arraycopy(streamHeaderPlaintext, INT_16_BYTES + INT_64_BYTES,
 				frameKeyBytes, 0, SecretKey.LENGTH);
 		frameKey = new SecretKey(frameKeyBytes);
 	}

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.crypto;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.ByteUtils;
 
 import java.io.IOException;
 import java.io.OutputStream;
@@ -11,7 +12,6 @@ import java.security.GeneralSecurityException;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
-import static java.lang.System.arraycopy;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_HEADER_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_HEADER_PLAINTEXT_LENGTH;
 import static org.briarproject.bramble.api.transport.TransportConstants.FRAME_NONCE_LENGTH;
@@ -24,8 +24,6 @@ import static org.briarproject.bramble.api.transport.TransportConstants.STREAM_H
 import static org.briarproject.bramble.api.transport.TransportConstants.STREAM_HEADER_PLAINTEXT_LENGTH;
 import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.writeUint16;
-import static org.briarproject.bramble.util.ByteUtils.writeUint64;
 
 @NotThreadSafe
 @NotNullByDefault
@@ -90,7 +88,7 @@ class StreamEncrypterImpl implements StreamEncrypter {
 			throw new RuntimeException(badCipher);
 		}
 		// Combine the payload and padding
-		arraycopy(payload, 0, framePlaintext, 0, payloadLength);
+		System.arraycopy(payload, 0, framePlaintext, 0, payloadLength);
 		for (int i = 0; i < paddingLength; i++)
 			framePlaintext[payloadLength + i] = 0;
 		// Encrypt and authenticate the payload and padding
@@ -120,12 +118,13 @@ class StreamEncrypterImpl implements StreamEncrypter {
 	private void writeStreamHeader() throws IOException {
 		// The header contains the protocol version, stream number and frame key
 		byte[] streamHeaderPlaintext = new byte[STREAM_HEADER_PLAINTEXT_LENGTH];
-		writeUint16(PROTOCOL_VERSION, streamHeaderPlaintext, 0);
-		writeUint64(streamNumber, streamHeaderPlaintext, INT_16_BYTES);
-		arraycopy(frameKey.getBytes(), 0, streamHeaderPlaintext,
+		ByteUtils.writeUint16(PROTOCOL_VERSION, streamHeaderPlaintext, 0);
+		ByteUtils.writeUint64(streamNumber, streamHeaderPlaintext,
+				INT_16_BYTES);
+		System.arraycopy(frameKey.getBytes(), 0, streamHeaderPlaintext,
 				INT_16_BYTES + INT_64_BYTES, SecretKey.LENGTH);
 		byte[] streamHeaderCiphertext = new byte[STREAM_HEADER_LENGTH];
-		arraycopy(streamHeaderNonce, 0, streamHeaderCiphertext, 0,
+		System.arraycopy(streamHeaderNonce, 0, streamHeaderCiphertext, 0,
 				STREAM_HEADER_NONCE_LENGTH);
 		// Encrypt and authenticate the stream header key
 		try {

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

@@ -7,12 +7,13 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
+import org.briarproject.bramble.util.ByteUtils;
+import org.briarproject.bramble.util.StringUtils;
 import org.spongycastle.crypto.Digest;
 import org.spongycastle.crypto.digests.Blake2bDigest;
 
 import javax.inject.Inject;
 
-import static java.lang.System.arraycopy;
 import static org.briarproject.bramble.api.transport.TransportConstants.ALICE_HEADER_LABEL;
 import static org.briarproject.bramble.api.transport.TransportConstants.ALICE_TAG_LABEL;
 import static org.briarproject.bramble.api.transport.TransportConstants.BOB_HEADER_LABEL;
@@ -23,9 +24,6 @@ import static org.briarproject.bramble.util.ByteUtils.INT_16_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.INT_64_BYTES;
 import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
 import static org.briarproject.bramble.util.ByteUtils.MAX_32_BIT_UNSIGNED;
-import static org.briarproject.bramble.util.ByteUtils.writeUint16;
-import static org.briarproject.bramble.util.ByteUtils.writeUint64;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 class TransportCryptoImpl implements TransportCrypto {
 
@@ -93,21 +91,21 @@ class TransportCryptoImpl implements TransportCrypto {
 
 	private SecretKey rotateKey(SecretKey k, long rotationPeriod) {
 		byte[] period = new byte[INT_64_BYTES];
-		writeUint64(rotationPeriod, period, 0);
+		ByteUtils.writeUint64(rotationPeriod, period, 0);
 		return crypto.deriveKey(ROTATE_LABEL, k, period);
 	}
 
 	private SecretKey deriveTagKey(SecretKey master, TransportId t,
 			boolean alice) {
 		String label = alice ? ALICE_TAG_LABEL : BOB_TAG_LABEL;
-		byte[] id = toUtf8(t.getString());
+		byte[] id = StringUtils.toUtf8(t.getString());
 		return crypto.deriveKey(label, master, id);
 	}
 
 	private SecretKey deriveHeaderKey(SecretKey master, TransportId t,
 			boolean alice) {
 		String label = alice ? ALICE_HEADER_LABEL : BOB_HEADER_LABEL;
-		byte[] id = toUtf8(t.getString());
+		byte[] id = StringUtils.toUtf8(t.getString());
 		return crypto.deriveKey(label, master, id);
 	}
 
@@ -127,14 +125,14 @@ class TransportCryptoImpl implements TransportCrypto {
 		// The input is the protocol version as a 16-bit integer, followed by
 		// the stream number as a 64-bit integer
 		byte[] protocolVersionBytes = new byte[INT_16_BYTES];
-		writeUint16(protocolVersion, protocolVersionBytes, 0);
+		ByteUtils.writeUint16(protocolVersion, protocolVersionBytes, 0);
 		prf.update(protocolVersionBytes, 0, protocolVersionBytes.length);
 		byte[] streamNumberBytes = new byte[INT_64_BYTES];
-		writeUint64(streamNumber, streamNumberBytes, 0);
+		ByteUtils.writeUint64(streamNumber, streamNumberBytes, 0);
 		prf.update(streamNumberBytes, 0, streamNumberBytes.length);
 		byte[] mac = new byte[macLength];
 		prf.doFinal(mac, 0);
 		// The output is the first TAG_LENGTH bytes of the MAC
-		arraycopy(mac, 0, tag, 0, TAG_LENGTH);
+		System.arraycopy(mac, 0, tag, 0, TAG_LENGTH);
 	}
 }

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.
@@ -242,7 +242,7 @@ interface Database<T> {
 	 * bytes. This is based on the minimum of the space available on the device
 	 * where the database is stored and the database's configured size.
 	 */
-	long getFreeSpace();
+	long getFreeSpace() throws DbException;
 
 	/**
 	 * Returns the group with the given ID.
@@ -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
@@ -637,8 +637,7 @@ 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

@@ -19,7 +19,6 @@ 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 +42,7 @@ 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;
@@ -54,13 +54,13 @@ 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;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -71,13 +71,11 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
-import static java.util.Collections.singletonList;
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
 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;
@@ -88,7 +86,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	private static final Logger LOG =
-			getLogger(DatabaseComponentImpl.class.getName());
+			Logger.getLogger(DatabaseComponentImpl.class.getName());
 
 	private final Database<T> db;
 	private final Class<T> txnClass;
@@ -195,20 +193,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		}
 	}
 
-	@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());
@@ -580,7 +564,7 @@ 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))
@@ -620,8 +604,8 @@ 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();
@@ -629,8 +613,8 @@ 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();
@@ -877,7 +861,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void setContactAlias(Transaction transaction, ContactId c,
-			@Nullable String alias) throws DbException {
+			String alias) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
@@ -899,7 +883,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		if (old == INVISIBLE) db.addGroupVisibility(txn, c, g, v == SHARED);
 		else if (v == INVISIBLE) db.removeGroupVisibility(txn, c, g);
 		else db.setGroupVisibility(txn, c, g, v == SHARED);
-		List<ContactId> affected = singletonList(c);
+		List<ContactId> affected = Collections.singletonList(c);
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
 	}
 
@@ -919,7 +903,7 @@ 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))
@@ -936,10 +920,10 @@ 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/DatabaseTypes.java

@@ -3,7 +3,7 @@ package org.briarproject.bramble.db;
 class DatabaseTypes {
 
 	private final String hashType, secretType, binaryType;
-	private final String counterType, stringType;
+    private final String counterType, stringType;
 
 	public DatabaseTypes(String hashType, String secretType, String binaryType,
 			String counterType, String stringType) {
@@ -17,11 +17,11 @@ class DatabaseTypes {
 	/**
 	 * 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
+	 *	<li> _HASH
+	 *	<li> _SECRET
+	 *	<li> _BINARY
+	 *	<li> _COUNTER
+	 *	<li> _STRING
 	 */
 	String replaceTypes(String s) {
 		s = s.replaceAll("_HASH", hashType);

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

@@ -7,6 +7,7 @@ import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.io.File;
 import java.sql.Connection;
@@ -14,24 +15,16 @@ 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;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-
 /**
  * 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";
@@ -107,7 +100,7 @@ class H2Database extends JdbcDatabase {
 		Properties props = new Properties();
 		props.setProperty("user", "user");
 		// Separate the file password from the user password with a space
-		String hex = toHexString(key.getBytes());
+		String hex = StringUtils.toHexString(key.getBytes());
 		props.put("password", hex + " password");
 		return DriverManager.getConnection(getUrl(), props);
 	}
@@ -128,8 +121,8 @@ class H2Database extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
+			tryToClose(s);
+			tryToClose(c);
 			throw new DbException(e);
 		}
 	}

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

@@ -7,31 +7,23 @@ import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.io.File;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.sql.Statement;
-import 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;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-
 /**
  * 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";
@@ -80,8 +72,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
+			tryToClose(s);
+			tryToClose(c);
 			throw new DbException(e);
 		}
 	}
@@ -114,7 +106,7 @@ class HyperSqlDatabase extends JdbcDatabase {
 	protected Connection createConnection() throws SQLException {
 		SecretKey key = this.key;
 		if (key == null) throw new IllegalStateException();
-		String hex = toHexString(key.getBytes());
+		String hex = StringUtils.toHexString(key.getBytes());
 		return DriverManager.getConnection(url + ";crypt_key=" + hex);
 	}
 
@@ -130,8 +122,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			tryToClose(c, LOG, WARNING);
+			tryToClose(s);
+			tryToClose(c);
 			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

@@ -7,13 +7,15 @@ 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 java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 class Migration38_39 implements Migration<Connection> {
 
-	private static final Logger LOG = getLogger(Migration38_39.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(Migration38_39.class.getName());
 
 	@Override
 	public int getStartVersion() {
@@ -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

@@ -7,13 +7,15 @@ 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 java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 class Migration39_40 implements Migration<Connection> {
 
-	private static final Logger LOG = getLogger(Migration39_40.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(Migration39_40.class.getName());
 
 	@Override
 	public int getStartVersion() {
@@ -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

@@ -7,9 +7,11 @@ 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 java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 class Migration40_41 implements Migration<Connection> {
 
@@ -17,7 +19,7 @@ class Migration40_41 implements Migration<Connection> {
 
 	private final DatabaseTypes dbTypes;
 
-	Migration40_41(DatabaseTypes databaseTypes) {
+	public Migration40_41(DatabaseTypes databaseTypes) {
 		this.dbTypes = databaseTypes;
 	}
 
@@ -37,10 +39,18 @@ class Migration40_41 implements Migration<Connection> {
 		try {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE contacts"
-					+ dbTypes.replaceTypes(" ADD alias _STRING"));
+					+ dbTypes.replaceTypes(" ADD alias VARCHAR"));
 		} 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/identity/AuthorFactoryImpl.java

@@ -7,6 +7,8 @@ import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.util.ByteUtils;
+import org.briarproject.bramble.util.StringUtils;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
@@ -14,8 +16,6 @@ import javax.inject.Inject;
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorId.LABEL;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
-import static org.briarproject.bramble.util.ByteUtils.writeUint32;
-import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 @Immutable
 @NotNullByDefault
@@ -58,8 +58,8 @@ class AuthorFactoryImpl implements AuthorFactory {
 
 	private AuthorId getId(int formatVersion, String name, byte[] publicKey) {
 		byte[] formatVersionBytes = new byte[INT_32_BYTES];
-		writeUint32(formatVersion, formatVersionBytes, 0);
+		ByteUtils.writeUint32(formatVersion, formatVersionBytes, 0);
 		return new AuthorId(crypto.hash(LABEL, formatVersionBytes,
-				toUtf8(name), publicKey));
+				StringUtils.toUtf8(name), publicKey));
 	}
 }

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

@@ -16,7 +16,6 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
 
@@ -25,7 +24,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 class IdentityManagerImpl implements IdentityManager {
 
 	private static final Logger LOG =
-			getLogger(IdentityManagerImpl.class.getName());
+			Logger.getLogger(IdentityManagerImpl.class.getName());
 
 	private final DatabaseComponent db;
 	private final CryptoComponent crypto;
@@ -68,16 +67,27 @@ 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();

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

@@ -2,7 +2,7 @@ package org.briarproject.bramble.keyagreement;
 
 class AbortException extends Exception {
 
-	final boolean receivedAbort;
+	boolean receivedAbort;
 
 	AbortException() {
 		this(false);

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

@@ -20,14 +20,13 @@ import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
 
 @NotNullByDefault
 @ThreadSafe
 class ConnectionChooserImpl implements ConnectionChooser {
 
 	private static final Logger LOG =
-			getLogger(ConnectionChooserImpl.class.getName());
+			Logger.getLogger(ConnectionChooserImpl.class.getName());
 
 	private final Clock clock;
 	private final Executor ioExecutor;

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

@@ -30,7 +30,6 @@ import javax.annotation.Nullable;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.CONNECTION_TIMEOUT;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
@@ -42,7 +41,7 @@ class KeyAgreementConnector {
 	}
 
 	private static final Logger LOG =
-			getLogger(KeyAgreementConnector.class.getName());
+			Logger.getLogger(KeyAgreementConnector.class.getName());
 
 	private final Callbacks callbacks;
 	private final KeyAgreementCrypto keyAgreementCrypto;

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

@@ -28,7 +28,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
@@ -37,7 +36,7 @@ class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
 		KeyAgreementProtocol.Callbacks, KeyAgreementConnector.Callbacks {
 
 	private static final Logger LOG =
-			getLogger(KeyAgreementTaskImpl.class.getName());
+			Logger.getLogger(KeyAgreementTaskImpl.class.getName());
 
 	private final CryptoComponent crypto;
 	private final KeyAgreementCrypto keyAgreementCrypto;