Decouple poller from plugin manager.

.gitlab-ci.yml

@@ -1,11 +1,6 @@
 image: briar/ci-image-android:latest
 
-stages:
-- test
-- check_reproducibility
-
 test:
-  stage: test
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
@@ -17,7 +12,7 @@ test:
 
   script:
     - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom test
 
   after_script:
     # these file change every time but should not be cached
@@ -26,7 +21,6 @@ test:
 
 
 test_reproducible:
-  stage: check_reproducibility
   script:
     - "curl -X POST -F token=${RELEASE_CHECK_TOKEN} -F ref=master -F variables[RELEASE_TAG]=${CI_COMMIT_REF_NAME} https://code.briarproject.org/api/v4/projects/61/trigger/pipeline"
   only:

.idea/codeStyles/Project.xml

@@ -1,10 +1,16 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
+    <option name="RIGHT_MARGIN" value="100" />
     <AndroidXmlCodeStyleSettings>
-      <option name="ARRANGEMENT_SETTINGS_MIGRATED_TO_191" value="true" />
+      <option name="USE_CUSTOM_SETTINGS" value="true" />
     </AndroidXmlCodeStyleSettings>
     <JavaCodeStyleSettings>
       <option name="ANNOTATION_PARAMETER_WRAP" value="1" />
+      <option name="CLASS_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99" />
+      <option name="NAMES_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99" />
+      <option name="PACKAGES_TO_USE_IMPORT_ON_DEMAND">
+        <value />
+      </option>
       <option name="IMPORT_LAYOUT_TABLE">
         <value>
           <package name="android" withSubpackages="true" static="false" />
@@ -71,6 +77,7 @@
       </indentOptions>
     </codeStyleSettings>
     <codeStyleSettings language="XML">
+      <option name="FORCE_REARRANGE_MODE" value="1" />
       <indentOptions>
         <option name="CONTINUATION_INDENT_SIZE" value="4" />
         <option name="USE_TAB_CHARACTER" value="true" />
@@ -83,8 +90,7 @@
               <match>
                 <AND>
                   <NAME>xmlns:android</NAME>
-                  <XML_ATTRIBUTE />
+                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
             </rule>
@@ -94,8 +100,7 @@
               <match>
                 <AND>
                   <NAME>xmlns:.*</NAME>
-                  <XML_ATTRIBUTE />
+                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
-                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
               <order>BY_NAME</order>
@@ -106,7 +111,6 @@
               <match>
                 <AND>
                   <NAME>.*:id</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
@@ -117,7 +121,6 @@
               <match>
                 <AND>
                   <NAME>.*:name</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
@@ -128,7 +131,6 @@
               <match>
                 <AND>
                   <NAME>name</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -139,7 +141,6 @@
               <match>
                 <AND>
                   <NAME>style</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -150,7 +151,6 @@
               <match>
                 <AND>
                   <NAME>.*</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -161,12 +161,64 @@
             <rule>
               <match>
                 <AND>
-                  <NAME>.*</NAME>
+                  <NAME>.*:layout_width</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
-              <order>ANDROID_ATTRIBUTE_ORDER</order>
+            </rule>
+          </section>
+          <section>
+            <rule>
+              <match>
+                <AND>
+                  <NAME>.*:layout_height</NAME>
+                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
+                </AND>
+              </match>
+            </rule>
+          </section>
+          <section>
+            <rule>
+              <match>
+                <AND>
+                  <NAME>.*:layout_.*</NAME>
+                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
+                </AND>
+              </match>
+              <order>BY_NAME</order>
+            </rule>
+          </section>
+          <section>
+            <rule>
+              <match>
+                <AND>
+                  <NAME>.*:width</NAME>
+                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
+                </AND>
+              </match>
+              <order>BY_NAME</order>
+            </rule>
+          </section>
+          <section>
+            <rule>
+              <match>
+                <AND>
+                  <NAME>.*:height</NAME>
+                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
+                </AND>
+              </match>
+              <order>BY_NAME</order>
+            </rule>
+          </section>
+          <section>
+            <rule>
+              <match>
+                <AND>
+                  <NAME>.*</NAME>
+                  <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
+                </AND>
+              </match>
+              <order>BY_NAME</order>
             </rule>
           </section>
           <section>
@@ -174,7 +226,6 @@
               <match>
                 <AND>
                   <NAME>.*</NAME>
-                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>.*</XML_NAMESPACE>
                 </AND>
               </match>

.idea/runConfigurations/All_in_briar_headless.xml

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

.idea/runConfigurations/All_tests.xml

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

.idea/runConfigurations/All_tests_in_briar_headless.xml

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

bramble-android/build.gradle

@@ -5,31 +5,23 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion 29
+	compileSdkVersion 28
-	buildToolsVersion '29.0.2'
+	buildToolsVersion '28.0.3'
 
 	defaultConfig {
-		minSdkVersion 16
+		minSdkVersion 14
-		targetSdkVersion 28
+		targetSdkVersion 26
-		versionCode 10207
+		versionCode 10106
-		versionName "1.2.7"
+		versionName "1.1.6"
 		consumerProguardFiles 'proguard-rules.txt'
 
-		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
 	}
 
 	compileOptions {
 		sourceCompatibility JavaVersion.VERSION_1_8
 		targetCompatibility JavaVersion.VERSION_1_8
 	}
-
-	lintOptions {
-		// FIXME
-		warning "LintError"
-		warning "InvalidPackage"
-		warning "MissingPermission"
-		warning "InlinedApi", "ObsoleteSdkInt", "Override", "NewApi", "UnusedAttribute"
-	}
 }
 
 configurations {
@@ -38,10 +30,10 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.10@zip'
+	tor 'org.briarproject:tor-android:0.3.5.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.9@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
@@ -67,8 +59,6 @@ task unpackTorBinaries {
 		copy {
 			from configurations.tor.collect { zipTree(it) }
 			into torBinariesDir
-			// TODO: Remove after next Tor upgrade, which won't include non-PIE binaries
-			include 'geoip.zip', '*_pie.zip'
 		}
 	}
 	dependsOn cleanTorBinaries

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

@@ -2,23 +2,10 @@ package org.briarproject.bramble;
 
 import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
-import org.briarproject.bramble.reporting.ReportingModule;
 
 public interface BrambleAndroidEagerSingletons {
 
 	void inject(AndroidBatteryModule.EagerSingletons init);
 
 	void inject(AndroidNetworkModule.EagerSingletons init);
-
-	void inject(ReportingModule.EagerSingletons init);
-
-	class Helper {
-
-		public static void injectEagerSingletons(
-				BrambleAndroidEagerSingletons c) {
-			c.inject(new AndroidBatteryModule.EagerSingletons());
-			c.inject(new AndroidNetworkModule.EagerSingletons());
-			c.inject(new ReportingModule.EagerSingletons());
-		}
-	}
 }

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

@@ -3,8 +3,6 @@ package org.briarproject.bramble;
 import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
 import org.briarproject.bramble.plugin.tor.CircumventionModule;
-import org.briarproject.bramble.reporting.ReportingModule;
-import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.system.AndroidSystemModule;
 
 import dagger.Module;
@@ -13,9 +11,12 @@ import dagger.Module;
 		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
-		CircumventionModule.class,
+		CircumventionModule.class
-		ReportingModule.class,
-		SocksModule.class
 })
 public class BrambleAndroidModule {
+
+	public static void initEagerSingletons(BrambleAndroidEagerSingletons c) {
+		c.inject(new AndroidBatteryModule.EagerSingletons());
+		c.inject(new AndroidNetworkModule.EagerSingletons());
+	}
 }

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

@@ -9,22 +9,17 @@ import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Set;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
 import static android.os.Build.VERSION.SDK_INT;
-import static java.util.Arrays.asList;
-import static java.util.logging.Level.INFO;
-import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
-import static org.briarproject.bramble.util.LogUtils.logFileOrDir;
 
 class AndroidAccountManager extends AccountManagerImpl
 		implements AccountManager {
@@ -32,11 +27,7 @@ class AndroidAccountManager extends AccountManagerImpl
 	private static final Logger LOG =
 			Logger.getLogger(AndroidAccountManager.class.getName());
 
-	/**
+	private static final String PREF_DB_KEY = "key";
-	 * Directories that shouldn't be deleted when deleting the user's account.
-	 */
-	private static final List<String> PROTECTED_DIR_NAMES =
-			asList("cache", "code_cache", "lib", "shared_prefs");
 
 	protected final Context appContext;
 	private final SharedPreferences prefs;
@@ -50,30 +41,42 @@ class AndroidAccountManager extends AccountManagerImpl
 		appContext = app.getApplicationContext();
 	}
 
+	// Locking: stateChangeLock
 	@Override
-	public boolean accountExists() {
+	@Nullable
-		boolean exists = super.accountExists();
+	protected String loadEncryptedDatabaseKey() {
-		if (!exists && LOG.isLoggable(INFO)) {
+		String key = getDatabaseKeyFromPreferences();
-			LOG.info("Account does not exist. Contents of account directory:");
+		if (key == null) key = super.loadEncryptedDatabaseKey();
-			logFileOrDir(LOG, INFO, getDataDir());
+		else migrateDatabaseKeyToFile(key);
+		return key;
+	}
+
+	// Locking: stateChangeLock
+	@Nullable
+	private String getDatabaseKeyFromPreferences() {
+		String key = prefs.getString(PREF_DB_KEY, null);
+		if (key == null) LOG.info("No database key in preferences");
+		else LOG.info("Found database key in preferences");
+		return key;
+	}
+
+	// Locking: stateChangeLock
+	private void migrateDatabaseKeyToFile(String key) {
+		if (storeEncryptedDatabaseKey(key)) {
+			if (prefs.edit().remove(PREF_DB_KEY).commit())
+				LOG.info("Database key migrated to file");
+			else LOG.warning("Database key not removed from preferences");
+		} else {
+			LOG.warning("Database key not migrated to file");
 		}
-		return exists;
 	}
 
 	@Override
 	public void deleteAccount() {
 		synchronized (stateChangeLock) {
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Contents of account directory before deleting:");
-				logFileOrDir(LOG, INFO, getDataDir());
-			}
 			super.deleteAccount();
 			SharedPreferences defaultPrefs = getDefaultSharedPreferences();
 			deleteAppData(prefs, defaultPrefs);
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Contents of account directory after deleting:");
-				logFileOrDir(LOG, INFO, getDataDir());
-			}
 		}
 	}
 
@@ -82,28 +85,30 @@ 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) {
 			if (!prefs.edit().clear().commit())
 				LOG.warning("Could not clear shared preferences");
 		}
-		// Delete files, except protected directories
+		// Delete files, except lib and shared_prefs directories
 		Set<File> files = new HashSet<>();
-		File dataDir = getDataDir();
+		File dataDir = new File(appContext.getApplicationInfo().dataDir);
 		@Nullable
 		File[] fileArray = dataDir.listFiles();
 		if (fileArray == null) {
 			LOG.warning("Could not list files in app data dir");
 		} else {
 			for (File file : fileArray) {
-				if (!PROTECTED_DIR_NAMES.contains(file.getName())) {
+				String name = file.getName();
+				if (!name.equals("lib") && !name.equals("shared_prefs")) {
 					files.add(file);
 				}
 			}
 		}
 		files.add(appContext.getFilesDir());
+		files.add(appContext.getCacheDir());
 		addIfNotNull(files, appContext.getExternalCacheDir());
 		if (SDK_INT >= 19) {
 			for (File file : appContext.getExternalCacheDirs()) {
@@ -115,20 +120,12 @@ class AndroidAccountManager extends AccountManagerImpl
 				addIfNotNull(files, file);
 			}
 		}
-		// Clear the cache directory but don't delete it
-		File cacheDir = appContext.getCacheDir();
-		File[] children = cacheDir.listFiles();
-		if (children != null) files.addAll(asList(children));
 		for (File file : files) {
-			if (LOG.isLoggable(INFO)) {
+			IoUtils.deleteFileOrDir(file);
-				LOG.info("Deleting " + file.getAbsolutePath());
-			}
-			deleteFileOrDir(file);
 		}
-	}
+		// Recreate the cache dir as some OpenGL drivers expect it to exist
-
+		if (!new File(dataDir, "cache").mkdirs())
-	private File getDataDir() {
+			LOG.warning("Could not recreate cache dir");
-		return new File(appContext.getApplicationInfo().dataDir);
 	}
 
 	private void addIfNotNull(Set<File> files, @Nullable File file) {

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

@@ -32,7 +32,6 @@ import static android.content.Intent.ACTION_SCREEN_OFF;
 import static android.content.Intent.ACTION_SCREEN_ON;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
-import static android.net.wifi.p2p.WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED;
 import static java.util.concurrent.TimeUnit.MINUTES;
@@ -77,9 +76,9 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		filter.addAction(ACTION_SCREEN_ON);
 		filter.addAction(ACTION_SCREEN_OFF);
 		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
-		filter.addAction(WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
 		if (SDK_INT >= 23) filter.addAction(ACTION_DEVICE_IDLE_MODE_CHANGED);
 		appContext.registerReceiver(networkStateReceiver, filter);
+
 	}
 
 	@Override
@@ -137,8 +136,7 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		}
 
 		private boolean isApEvent(@Nullable String action) {
-			return WIFI_AP_STATE_CHANGED_ACTION.equals(action) ||
+			return WIFI_AP_STATE_CHANGED_ACTION.equals(action);
-					WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action);
 		}
 	}
 }

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

@@ -9,11 +9,11 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 
-import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginException;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
@@ -24,13 +24,13 @@ import java.io.IOException;
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -47,14 +47,10 @@ import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
 import static android.bluetooth.BluetoothAdapter.STATE_OFF;
 import static android.bluetooth.BluetoothAdapter.STATE_ON;
 import static android.bluetooth.BluetoothDevice.ACTION_FOUND;
-import static android.bluetooth.BluetoothDevice.DEVICE_TYPE_LE;
 import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
-import static android.os.Build.VERSION.SDK_INT;
-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.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
@@ -62,11 +58,10 @@ 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;
 
-	private final ScheduledExecutorService scheduler;
 	private final AndroidExecutor androidExecutor;
 	private final Context appContext;
 	private final Clock clock;
@@ -78,14 +73,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private volatile BluetoothAdapter adapter = null;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
+			Executor ioExecutor, AndroidExecutor androidExecutor,
-			SecureRandom secureRandom, ScheduledExecutorService scheduler,
+			Context appContext, SecureRandom secureRandom, Clock clock,
-			AndroidExecutor androidExecutor, Context appContext, Clock clock,
+			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
-			PluginCallback callback, int maxLatency, int maxIdleTime,
+		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
-			int pollingInterval) {
+				maxLatency);
-		super(connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
-				callback, maxLatency, maxIdleTime, pollingInterval);
-		this.scheduler = scheduler;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.clock = clock;
@@ -153,12 +145,6 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		wasEnabledByUs = true;
 	}
 
-	@Override
-	void onAdapterDisabled() {
-		super.onAdapterDisabled();
-		wasEnabledByUs = false;
-	}
-
 	@Override
 	@Nullable
 	String getBluetoothAddress() {
@@ -183,10 +169,9 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return wrapSocket(ss.accept());
 	}
 
-	private DuplexTransportConnection wrapSocket(BluetoothSocket s)
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-			throws IOException {
+		return new AndroidBluetoothTransportConnection(this,
-		return new AndroidBluetoothTransportConnection(this, connectionLimiter,
+				connectionLimiter, s);
-				timeoutMonitor, appContext, scheduler, s);
 	}
 
 	@Override
@@ -254,15 +239,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 						break;
 					} else if (ACTION_FOUND.equals(action)) {
 						BluetoothDevice d = i.getParcelableExtra(EXTRA_DEVICE);
-						// Ignore Bluetooth LE devices
+						String address = d.getAddress();
-						if (SDK_INT < 18 || d.getType() != DEVICE_TYPE_LE) {
+						if (LOG.isLoggable(INFO))
-							String address = d.getAddress();
+							LOG.info("Discovered " + scrubMacAddress(address));
-							if (LOG.isLoggable(INFO))
+						if (!addresses.contains(address))
-								LOG.info("Discovered " +
+							addresses.add(address);
-										scrubMacAddress(address));
-							if (!addresses.contains(address))
-								addresses.add(address);
-						}
 					}
 					now = clock.currentTimeMillis();
 				}
@@ -278,7 +259,7 @@ 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;
 	}
 

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

@@ -3,55 +3,51 @@ package org.briarproject.bramble.plugin.bluetooth;
 import android.content.Context;
 
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
-import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
+	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
-	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
+	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
-	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(2);
+	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
+	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
-	private final ScheduledExecutorService scheduler;
 	private final AndroidExecutor androidExecutor;
 	private final Context appContext;
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
 	private final Clock clock;
-	private final TimeoutMonitor timeoutMonitor;
+	private final BackoffFactory backoffFactory;
 
 	public AndroidBluetoothPluginFactory(Executor ioExecutor,
-			ScheduledExecutorService scheduler,
 			AndroidExecutor androidExecutor, Context appContext,
 			SecureRandom secureRandom, EventBus eventBus, Clock clock,
-			TimeoutMonitor timeoutMonitor) {
+			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
-		this.scheduler = scheduler;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
 		this.clock = clock;
-		this.timeoutMonitor = timeoutMonitor;
+		this.backoffFactory = backoffFactory;
 	}
 
 	@Override
@@ -65,13 +61,14 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl();
+		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
-				connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
+				connectionLimiter, ioExecutor, androidExecutor, appContext,
-				scheduler, androidExecutor, appContext, clock, callback,
+				secureRandom, clock, backoff, callback, MAX_LATENCY);
-				MAX_LATENCY, MAX_IDLE_TIME, POLLING_INTERVAL);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -1,60 +1,33 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
-import android.content.Context;
-import android.os.PowerManager;
 
-import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
-import org.briarproject.bramble.util.RenewableWakeLock;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.concurrent.ScheduledExecutorService;
-
-import static android.content.Context.POWER_SERVICE;
-import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
-import static org.briarproject.bramble.util.AndroidUtils.getWakeLockTag;
-import static org.briarproject.bramble.util.AndroidUtils.isValidBluetoothAddress;
 
 @NotNullByDefault
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
-	private final BluetoothConnectionLimiter connectionLimiter;
+	private final BluetoothConnectionLimiter connectionManager;
-	private final RenewableWakeLock wakeLock;
 	private final BluetoothSocket socket;
-	private final InputStream in;
 
 	AndroidBluetoothTransportConnection(Plugin plugin,
-			BluetoothConnectionLimiter connectionLimiter,
+			BluetoothConnectionLimiter connectionManager,
-			TimeoutMonitor timeoutMonitor, Context appContext,
+			BluetoothSocket socket) {
-			ScheduledExecutorService scheduler, BluetoothSocket socket)
-			throws IOException {
 		super(plugin);
-		this.connectionLimiter = connectionLimiter;
+		this.connectionManager = connectionManager;
 		this.socket = socket;
-		in = timeoutMonitor.createTimeoutInputStream(
-				socket.getInputStream(), plugin.getMaxIdleTime() * 2);
-		PowerManager powerManager = (PowerManager)
-				requireNonNull(appContext.getSystemService(POWER_SERVICE));
-		String tag = getWakeLockTag(appContext);
-		wakeLock = new RenewableWakeLock(powerManager, scheduler,
-				PARTIAL_WAKE_LOCK, tag, 1, MINUTES);
-		wakeLock.acquire();
-		String address = socket.getRemoteDevice().getAddress();
-		if (isValidBluetoothAddress(address)) remote.put(PROP_ADDRESS, address);
 	}
 
 	@Override
-	protected InputStream getInputStream() {
+	protected InputStream getInputStream() throws IOException {
-		return in;
+		return socket.getInputStream();
 	}
 
 	@Override
@@ -67,8 +40,7 @@ class AndroidBluetoothTransportConnection
 		try {
 			socket.close();
 		} finally {
-			wakeLock.release();
+			connectionManager.connectionClosed(this);
-			connectionLimiter.connectionClosed(this);
 		}
 	}
 }

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

@@ -1,31 +1,25 @@
 package org.briarproject.bramble.plugin.tcp;
 
-import android.annotation.TargetApi;
 import android.content.Context;
 import android.net.ConnectivityManager;
-import android.net.LinkAddress;
-import android.net.LinkProperties;
 import android.net.Network;
-import android.net.NetworkCapabilities;
+import android.net.NetworkInfo;
 import android.net.wifi.WifiInfo;
 import android.net.wifi.WifiManager;
 
 import org.briarproject.bramble.PoliteExecutor;
-import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 
 import java.io.IOException;
 import java.net.InetAddress;
-import java.net.InterfaceAddress;
-import java.net.NetworkInterface;
 import java.net.Socket;
-import java.net.SocketException;
 import java.net.UnknownHostException;
-import java.util.List;
+import java.util.Collection;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -34,24 +28,29 @@ import javax.net.SocketFactory;
 
 import static android.content.Context.CONNECTIVITY_SERVICE;
 import static android.content.Context.WIFI_SERVICE;
-import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
+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.list;
 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.plugin.LanTcpConstants.DEFAULT_PREF_PLUGIN_ENABLE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
-import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-class AndroidLanTcpPlugin extends LanTcpPlugin {
+class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
+
+	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 =
-			getLogger(AndroidLanTcpPlugin.class.getName());
+			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
+
+	static {
+		try {
+			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
+		} catch (UnknownHostException e) {
+			// Should only be thrown if the address has an illegal length
+			throw new AssertionError(e);
+		}
+	}
 
 	private final Executor connectionStatusExecutor;
 	private final ConnectivityManager connectivityManager;
@@ -61,10 +60,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	private volatile SocketFactory socketFactory;
 
 	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
-			PluginCallback callback, int maxLatency, int maxIdleTime,
+			Backoff backoff, DuplexPluginCallback callback, int maxLatency,
-			int pollingInterval, int connectionTimeout) {
+			int maxIdleTime) {
-		super(ioExecutor, callback, maxLatency, maxIdleTime, pollingInterval,
+		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
-				connectionTimeout);
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("AndroidLanTcpPlugin", ioExecutor, 1);
@@ -80,138 +78,34 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		initialisePortProperty();
+		running = true;
-		Settings settings = callback.getSettings();
-		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE,
-				DEFAULT_PREF_PLUGIN_ENABLE));
 		updateConnectionStatus();
 	}
 
+	@Override
+	public void stop() {
+		running = false;
+		tryToClose(socket);
+	}
+
 	@Override
 	protected Socket createSocket() throws IOException {
 		return socketFactory.createSocket();
 	}
 
 	@Override
-	protected List<InetAddress> getUsableLocalInetAddresses(boolean ipv4) {
+	protected Collection<InetAddress> getLocalIpAddresses() {
-		InetAddress addr = getWifiAddress(ipv4);
+		// If the device doesn't have wifi, don't open any sockets
-		return addr == null ? emptyList() : singletonList(addr);
+		if (wifiManager == null) return emptyList();
-	}
+		// If we're connected to a wifi network, use that network
-
-	@Nullable
-	private InetAddress getWifiAddress(boolean ipv4) {
-		Pair<InetAddress, Boolean> wifi = getWifiIpv4Address();
-		if (ipv4) return wifi == null ? null : wifi.getFirst();
-		// If there's no wifi IPv4 address, we might be a client on an
-		// IPv6-only wifi network. We can only detect this on API 21+
-		if (wifi == null) {
-			return SDK_INT >= 21 ? getWifiClientIpv6Address() : null;
-		}
-		// Use the wifi IPv4 address to determine which interface's IPv6
-		// address we should return (if the interface has a suitable address)
-		return getIpv6AddressForInterface(wifi.getFirst());
-	}
-
-	/**
-	 * Returns a {@link Pair} where the first element is the IPv4 address of
-	 * the wifi interface and the second element is true if this device is
-	 * providing an access point, or false if this device is a client. Returns
-	 * null if this device isn't connected to wifi as an access point or client.
-	 */
-	@Nullable
-	private Pair<InetAddress, Boolean> getWifiIpv4Address() {
-		if (wifiManager == null) return null;
-		// If we're connected to a wifi network, return its address
 		WifiInfo info = wifiManager.getConnectionInfo();
-		if (info != null && info.getIpAddress() != 0) {
+		if (info != null && info.getIpAddress() != 0)
-			return new Pair<>(intToInetAddress(info.getIpAddress()), false);
+			return singletonList(intToInetAddress(info.getIpAddress()));
-		}
+		// If we're running an access point, return its address
-		List<InterfaceAddress> ifAddrs = getLocalInterfaceAddresses();
+		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
-		// If we're providing a normal access point, return its address
+			return singletonList(WIFI_AP_ADDRESS);
-		for (InterfaceAddress ifAddr : ifAddrs) {
+		// No suitable addresses
-			if (isAndroidWifiApAddress(ifAddr)) {
+		return emptyList();
-				return new Pair<>(ifAddr.getAddress(), true);
-			}
-		}
-		// If we're providing a wifi direct access point, return its address
-		for (InterfaceAddress ifAddr : ifAddrs) {
-			if (isAndroidWifiDirectApAddress(ifAddr)) {
-				return new Pair<>(ifAddr.getAddress(), true);
-			}
-		}
-		// Not connected to wifi
-		return null;
-	}
-
-	/**
-	 * Returns true if the given address belongs to a network provided by an
-	 * Android access point (including the access point's own address).
-	 * <p>
-	 * The access point's address is usually 192.168.43.1, but at least one
-	 * device (Honor 8A) may use other addresses in the range 192.168.43.0/24.
-	 */
-	private boolean isAndroidWifiApAddress(InterfaceAddress ifAddr) {
-		if (ifAddr.getNetworkPrefixLength() != 24) return false;
-		byte[] ip = ifAddr.getAddress().getAddress();
-		return ip.length == 4
-				&& ip[0] == (byte) 192
-				&& ip[1] == (byte) 168
-				&& ip[2] == (byte) 43;
-	}
-
-	/**
-	 * Returns true if the given address belongs to a network provided by an
-	 * Android wifi direct legacy mode access point (including the access
-	 * point's own address).
-	 */
-	private boolean isAndroidWifiDirectApAddress(InterfaceAddress ifAddr) {
-		if (ifAddr.getNetworkPrefixLength() != 24) return false;
-		byte[] ip = ifAddr.getAddress().getAddress();
-		return ip.length == 4
-				&& ip[0] == (byte) 192
-				&& ip[1] == (byte) 168
-				&& ip[2] == (byte) 49;
-	}
-
-	/**
-	 * Returns a link-local IPv6 address for the wifi client interface, or null
-	 * if there's no such interface or it doesn't have a suitable address.
-	 */
-	@TargetApi(21)
-	@Nullable
-	private InetAddress getWifiClientIpv6Address() {
-		for (Network net : connectivityManager.getAllNetworks()) {
-			NetworkCapabilities caps =
-					connectivityManager.getNetworkCapabilities(net);
-			if (caps == null || !caps.hasTransport(TRANSPORT_WIFI)) continue;
-			LinkProperties props = connectivityManager.getLinkProperties(net);
-			if (props == null) continue;
-			for (LinkAddress linkAddress : props.getLinkAddresses()) {
-				InetAddress addr = linkAddress.getAddress();
-				if (isIpv6LinkLocalAddress(addr)) return addr;
-			}
-		}
-		return null;
-	}
-
-	/**
-	 * Returns a link-local IPv6 address for the interface with the given IPv4
-	 * address, or null if the interface doesn't have a suitable address.
-	 */
-	@Nullable
-	private InetAddress getIpv6AddressForInterface(InetAddress ipv4) {
-		try {
-			NetworkInterface iface = NetworkInterface.getByInetAddress(ipv4);
-			if (iface == null) return null;
-			for (InetAddress addr : list(iface.getInetAddresses())) {
-				if (isIpv6LinkLocalAddress(addr)) return addr;
-			}
-			// No suitable address
-			return null;
-		} catch (SocketException e) {
-			logException(LOG, WARNING, e);
-			return null;
-		}
 	}
 
 	private InetAddress intToInetAddress(int ip) {
@@ -233,11 +127,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	private SocketFactory getSocketFactory() {
 		if (SDK_INT < 21) return SocketFactory.getDefault();
 		for (Network net : connectivityManager.getAllNetworks()) {
-			NetworkCapabilities caps =
+			NetworkInfo info = connectivityManager.getNetworkInfo(net);
-					connectivityManager.getNetworkCapabilities(net);
+			if (info != null && info.getType() == TYPE_WIFI)
-			if (caps != null && caps.hasTransport(TRANSPORT_WIFI)) {
 				return net.getSocketFactory();
-			}
 		}
 		LOG.warning("Could not find suitable socket factory");
 		return SocketFactory.getDefault();
@@ -245,59 +137,30 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 
 	@Override
 	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
 		if (e instanceof NetworkStatusEvent) updateConnectionStatus();
 	}
 
 	private void updateConnectionStatus() {
 		connectionStatusExecutor.execute(() -> {
-			State s = getState();
+			if (!running) return;
-			if (s != ACTIVE && s != INACTIVE) return;
+			Collection<InetAddress> addrs = getLocalIpAddresses();
-			Pair<InetAddress, Boolean> wifi = getPreferredWifiAddress();
+			if (addrs.contains(WIFI_AP_ADDRESS)) {
-			if (wifi == null) {
-				LOG.info("Not connected to wifi");
-				socketFactory = SocketFactory.getDefault();
-				// Server sockets may not have been closed automatically when
-				// interface was taken down. If any sockets are open, closing
-				// them here will cause the sockets to be cleared and the state
-				// to be updated in acceptContactConnections()
-				if (s == ACTIVE) {
-					LOG.info("Closing server sockets");
-					tryToClose(state.getServerSocket(true), LOG, WARNING);
-					tryToClose(state.getServerSocket(false), LOG, WARNING);
-				}
-			} else if (wifi.getSecond()) {
 				LOG.info("Providing wifi hotspot");
 				// There's no corresponding Network object and thus no way
 				// to get a suitable socket factory, so we won't be able to
 				// make outgoing connections on API 21+ if another network
 				// has internet access
 				socketFactory = SocketFactory.getDefault();
-				if (s == INACTIVE) bind();
+				if (socket == null || socket.isClosed()) bind();
+			} else if (addrs.isEmpty()) {
+				LOG.info("Not connected to wifi");
+				socketFactory = SocketFactory.getDefault();
+				tryToClose(socket);
 			} else {
 				LOG.info("Connected to wifi");
 				socketFactory = getSocketFactory();
-				if (s == INACTIVE) bind();
+				if (socket == null || socket.isClosed()) bind();
 			}
 		});
 	}
-
-	/**
-	 * Returns a {@link Pair} where the first element is an IP address (IPv4 if
-	 * available, otherwise IPv6) of the wifi interface and the second element
-	 * is true if this device is providing an access point, or false if this
-	 * device is a client. Returns null if this device isn't connected to wifi
-	 * as an access point or client.
-	 */
-	@Nullable
-	private Pair<InetAddress, Boolean> getPreferredWifiAddress() {
-		Pair<InetAddress, Boolean> wifi = getWifiIpv4Address();
-		// If there's no wifi IPv4 address, we might be a client on an
-		// IPv6-only wifi network. We can only detect this on API 21+
-		if (wifi == null && SDK_INT >= 21) {
-			InetAddress ipv6 = getWifiClientIpv6Address();
-			if (ipv6 != null) return new Pair<>(ipv6, false);
-		}
-		return wifi;
-	}
 }

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

@@ -4,36 +4,39 @@ import android.content.Context;
 
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
 
 import javax.annotation.concurrent.Immutable;
 
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
+	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
-	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
-	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(1);
+	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
-	private static final int CONNECTION_TIMEOUT = (int) SECONDS.toMillis(3);
+	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
+	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
 	private final EventBus eventBus;
+	private final BackoffFactory backoffFactory;
 	private final Context appContext;
 
 	public AndroidLanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
-			Context appContext) {
+			BackoffFactory backoffFactory, Context appContext) {
 		this.ioExecutor = ioExecutor;
 		this.eventBus = eventBus;
+		this.backoffFactory = backoffFactory;
 		this.appContext = appContext;
 	}
 
@@ -48,10 +51,11 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidLanTcpPlugin plugin = new AndroidLanTcpPlugin(ioExecutor,
-				appContext, callback, MAX_LATENCY, MAX_IDLE_TIME,
+				appContext, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME);
-				POLLING_INTERVAL, CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -10,7 +10,8 @@ import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
@@ -26,7 +27,6 @@ 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.concurrent.TimeUnit.MINUTES;
-import static org.briarproject.bramble.util.AndroidUtils.getWakeLockTag;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -40,22 +40,19 @@ class AndroidTorPlugin extends TorPlugin {
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager,
+			BatteryManager batteryManager, Backoff backoff,
-			TorRendezvousCrypto torRendezvousCrypto,
+			DuplexPluginCallback callback, String architecture, int maxLatency,
-			PluginCallback callback, String architecture, int maxLatency,
+			int maxIdleTime) {
-			int maxIdleTime, int initialPollingInterval,
-			int stablePollingInterval) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
 				clock, resourceProvider, circumventionProvider, batteryManager,
-				torRendezvousCrypto, callback, architecture, maxLatency,
+				backoff, callback, architecture, maxLatency, maxIdleTime,
-				maxIdleTime, initialPollingInterval, stablePollingInterval,
 				appContext.getDir("tor", MODE_PRIVATE));
 		this.appContext = appContext;
 		PowerManager pm = (PowerManager)
 				appContext.getSystemService(POWER_SERVICE);
 		if (pm == null) throw new AssertionError();
 		wakeLock = new RenewableWakeLock(pm, scheduler, PARTIAL_WAKE_LOCK,
-				getWakeLockTag(appContext), 1, MINUTES);
+				getWakeLockTag(), 1, MINUTES);
 	}
 
 	@Override
@@ -76,6 +73,7 @@ class AndroidTorPlugin extends TorPlugin {
 
 	@Override
 	protected void enableNetwork(boolean enable) throws IOException {
+		if (!running) return;
 		if (enable) wakeLock.acquire();
 		super.enableNetwork(enable);
 		if (!enable) wakeLock.release();
@@ -86,4 +84,17 @@ class AndroidTorPlugin extends TorPlugin {
 		super.stop();
 		wakeLock.release();
 	}
+
+	private String getWakeLockTag() {
+		PackageManager pm = appContext.getPackageManager();
+		for (PackageInfo info : pm.getInstalledPackages(0)) {
+			String name = info.packageName.toLowerCase();
+			if (name.startsWith("com.huawei.powergenie")) {
+				return "LocationManagerService";
+			} else if (name.startsWith("com.evenwell.powermonitor")) {
+				return "AudioIn";
+			}
+		}
+		return getClass().getSimpleName();
+	}
 }

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

@@ -1,15 +1,18 @@
 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;
-import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
@@ -23,33 +26,18 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.Immutable;
 import javax.net.SocketFactory;
 
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static java.util.concurrent.TimeUnit.SECONDS;
-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 = (int) SECONDS.toMillis(30);
+	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
-	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
-
+	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
-	/**
+	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
-	 * How often to poll before our hidden service becomes reachable.
+	private static final double BACKOFF_BASE = 1.2;
-	 */
-	private static final int INITIAL_POLLING_INTERVAL =
-			(int) MINUTES.toMillis(1);
-
-	/**
-	 * How often to poll when our hidden service is reachable. Our contacts
-	 * will poll when they come online, so our polling is just a fallback in
-	 * case of repeated connection failures.
-	 */
-	private static final int STABLE_POLLING_INTERVAL =
-			(int) MINUTES.toMillis(15);
 
 	private final Executor ioExecutor;
 	private final ScheduledExecutorService scheduler;
@@ -58,6 +46,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	private final LocationUtils locationUtils;
 	private final EventBus eventBus;
 	private final SocketFactory torSocketFactory;
+	private final BackoffFactory backoffFactory;
 	private final ResourceProvider resourceProvider;
 	private final CircumventionProvider circumventionProvider;
 	private final BatteryManager batteryManager;
@@ -67,7 +56,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			ScheduledExecutorService scheduler, Context appContext,
 			NetworkManager networkManager, LocationUtils locationUtils,
 			EventBus eventBus, SocketFactory torSocketFactory,
-			ResourceProvider resourceProvider,
+			BackoffFactory backoffFactory, ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager, Clock clock) {
 		this.ioExecutor = ioExecutor;
@@ -77,6 +66,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		this.locationUtils = locationUtils;
 		this.eventBus = eventBus;
 		this.torSocketFactory = torSocketFactory;
+		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
 		this.batteryManager = batteryManager;
@@ -94,20 +84,14 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(PluginCallback callback) {
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 
 		// Check that we have a Tor binary for this architecture
 		String architecture = null;
 		for (String abi : AndroidUtils.getSupportedArchitectures()) {
-			if (abi.startsWith("x86_64")) {
+			if (abi.startsWith("x86")) {
-				architecture = "x86_64";
-				break;
-			} else if (abi.startsWith("x86")) {
 				architecture = "x86";
 				break;
-			} else if (abi.startsWith("arm64")) {
-				architecture = "arm64";
-				break;
 			} else if (abi.startsWith("armeabi")) {
 				architecture = "arm";
 				break;
@@ -117,16 +101,15 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			LOG.info("Tor is not supported on this architecture");
 			return null;
 		}
-		// Use position-independent executable
+		// Use position-independent executable for SDK >= 16
-		architecture += "_pie";
+		if (Build.VERSION.SDK_INT >= 16) architecture += "_pie";
 
-		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
+		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,
-				torRendezvousCrypto, callback, architecture, MAX_LATENCY,
+				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
-				MAX_IDLE_TIME, INITIAL_POLLING_INTERVAL,
-				STABLE_POLLING_INTERVAL);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -61,12 +61,12 @@ class AndroidLocationUtils implements LocationUtils {
 	private String getCountryFromPhoneNetwork() {
 		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
 		TelephonyManager tm = (TelephonyManager) o;
-		return tm == null ? "" : tm.getNetworkCountryIso();
+		return tm.getNetworkCountryIso();
 	}
 
 	private String getCountryFromSimCard() {
 		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
 		TelephonyManager tm = (TelephonyManager) o;
-		return tm == null ? "" : tm.getSimCountryIso();
+		return tm.getSimCountryIso();
 	}
 }

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

@@ -23,7 +23,6 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static android.content.Context.WIFI_SERVICE;
-import static android.os.Build.VERSION.SDK_INT;
 import static android.provider.Settings.Secure.ANDROID_ID;
 
 @Immutable
@@ -75,7 +74,8 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		// Silence strict mode
 		StrictMode.ThreadPolicy tp = StrictMode.allowThreadDiskWrites();
 		super.writeSeed();
-		if (SDK_INT <= 18) applyOpenSslFix();
+		if (Build.VERSION.SDK_INT >= 16 && Build.VERSION.SDK_INT <= 18)
+			applyOpenSslFix();
 		StrictMode.setThreadPolicy(tp);
 	}
 

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

@@ -3,30 +3,18 @@ package org.briarproject.bramble.util;
 import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.content.pm.PackageManager;
 import android.os.Build;
 import android.provider.Settings;
 
-import org.briarproject.bramble.api.Pair;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
 import java.io.File;
-import java.lang.reflect.Field;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 
-import javax.annotation.Nullable;
-
 import static android.content.Context.MODE_PRIVATE;
 import static android.os.Build.VERSION.SDK_INT;
-import static java.util.Arrays.asList;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 
-@NotNullByDefault
 public class AndroidUtils {
 
 	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
@@ -34,10 +22,11 @@ public class AndroidUtils {
 
 	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(Build.SUPPORTED_ABIS));
+			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);
 			if (Build.CPU_ABI2 != null) abis.add(Build.CPU_ABI2);
@@ -47,89 +36,25 @@ public class AndroidUtils {
 
 	public static String getBluetoothAddress(Context ctx,
 			BluetoothAdapter adapter) {
-		return getBluetoothAddressAndMethod(ctx, adapter).getFirst();
-	}
-
-	public static Pair<String, String> getBluetoothAddressAndMethod(Context ctx,
-			BluetoothAdapter adapter) {
 		// Return the adapter's address if it's valid and not fake
 		@SuppressLint("HardwareIds")
 		String address = adapter.getAddress();
-		if (isValidBluetoothAddress(address)) {
+		if (isValidBluetoothAddress(address)) return address;
-			return new Pair<>(address, "adapter");
-		}
 		// Return the address from settings if it's valid and not fake
 		address = Settings.Secure.getString(ctx.getContentResolver(),
 				"bluetooth_address");
-		if (isValidBluetoothAddress(address)) {
+		if (isValidBluetoothAddress(address)) return address;
-			return new Pair<>(address, "settings");
-		}
-		// Try to get the address via reflection
-		address = getBluetoothAddressByReflection(adapter);
-		if (isValidBluetoothAddress(address)) {
-			return new Pair<>(requireNonNull(address), "reflection");
-		}
 		// Let the caller know we can't find the address
-		return new Pair<>("", "");
+		return "";
 	}
 
-	public static boolean isValidBluetoothAddress(@Nullable String address) {
+	private static boolean isValidBluetoothAddress(String address) {
 		return !StringUtils.isNullOrEmpty(address)
 				&& BluetoothAdapter.checkBluetoothAddress(address)
 				&& !address.equals(FAKE_BLUETOOTH_ADDRESS);
 	}
 
-	@Nullable
-	private static String getBluetoothAddressByReflection(
-			BluetoothAdapter adapter) {
-		try {
-			Field mServiceField =
-					adapter.getClass().getDeclaredField("mService");
-			mServiceField.setAccessible(true);
-			Object mService = mServiceField.get(adapter);
-			// mService may be null when Bluetooth is disabled
-			if (mService == null) throw new NoSuchFieldException();
-			Method getAddressMethod =
-					mService.getClass().getMethod("getAddress");
-			return (String) getAddressMethod.invoke(mService);
-		} catch (NoSuchFieldException e) {
-			return null;
-		} catch (IllegalAccessException e) {
-			return null;
-		} catch (NoSuchMethodException e) {
-			return null;
-		} catch (InvocationTargetException e) {
-			return null;
-		} catch (SecurityException e) {
-			return null;
-		}
-	}
-
 	public static File getReportDir(Context ctx) {
 		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
 	}
-
-	/**
-	 * Returns an array of supported content types for image attachments.
-	 * GIFs can't be compressed on API < 24 so they're not supported.
-	 * <p>
-	 * TODO: Remove this restriction when large message support is added
-	 */
-	public static String[] getSupportedImageContentTypes() {
-		if (SDK_INT < 24) return new String[] {"image/jpeg", "image/png"};
-		else return new String[] {"image/jpeg", "image/png", "image/gif"};
-	}
-
-	public static String getWakeLockTag(Context ctx) {
-		PackageManager pm = ctx.getPackageManager();
-		for (PackageInfo info : pm.getInstalledPackages(0)) {
-			String name = info.packageName.toLowerCase();
-			if (name.startsWith("com.huawei.powergenie")) {
-				return "LocationManagerService";
-			} else if (name.startsWith("com.evenwell.powermonitor")) {
-				return "AudioIn";
-			}
-		}
-		return ctx.getPackageName();
-	}
 }

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

@@ -16,10 +16,13 @@ import org.junit.Test;
 
 import java.io.File;
 
+import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertTrue;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.briarproject.bramble.test.TestUtils.getTestDirectory;
+import static org.briarproject.bramble.util.StringUtils.toHexString;
 
 public class AndroidAccountManagerTest extends BrambleMockTestCase {
 
@@ -37,8 +40,11 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 	private final Application app;
 	private final ApplicationInfo applicationInfo;
 
+	private final String encryptedKeyHex = toHexString(getRandomBytes(123));
 	private final File testDir = getTestDirectory();
 	private final File keyDir = new File(testDir, "key");
+	private final File keyFile = new File(keyDir, "db.key");
+	private final File keyBackupFile = new File(keyDir, "db.key.bak");
 	private final File dbDir = new File(testDir, "db");
 
 	private AndroidAccountManager accountManager;
@@ -69,12 +75,33 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 		};
 	}
 
+	@Test
+	public void testDbKeyIsMigratedFromPreferencesToFile() {
+		context.checking(new Expectations() {{
+			oneOf(prefs).getString("key", null);
+			will(returnValue(encryptedKeyHex));
+			oneOf(prefs).edit();
+			will(returnValue(editor));
+			oneOf(editor).remove("key");
+			will(returnValue(editor));
+			oneOf(editor).commit();
+			will(returnValue(true));
+		}});
+
+		assertFalse(keyFile.exists());
+		assertFalse(keyBackupFile.exists());
+
+		assertEquals(encryptedKeyHex,
+				accountManager.loadEncryptedDatabaseKey());
+
+		assertTrue(keyFile.exists());
+		assertTrue(keyBackupFile.exists());
+	}
+
 	@Test
 	public void testDeleteAccountClearsSharedPrefsAndDeletesFiles()
 			throws Exception {
-		// Directories 'code_cache', 'lib' and 'shared_prefs' should be spared
+		// Directories 'lib' and 'shared_prefs' should be spared
-		File codeCacheDir = new File(testDir, "code_cache");
-		File codeCacheFile = new File(codeCacheDir, "file");
 		File libDir = new File(testDir, "lib");
 		File libFile = new File(libDir, "file");
 		File sharedPrefsDir = new File(testDir, "shared_prefs");
@@ -101,7 +128,7 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 			will(returnValue(editor));
 			oneOf(editor).commit();
 			will(returnValue(true));
-			allowing(app).getApplicationInfo();
+			oneOf(app).getApplicationInfo();
 			will(returnValue(applicationInfo));
 			oneOf(app).getFilesDir();
 			will(returnValue(filesDir));
@@ -113,8 +140,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 
 		assertTrue(dbDir.mkdirs());
 		assertTrue(keyDir.mkdirs());
-		assertTrue(codeCacheDir.mkdirs());
-		assertTrue(codeCacheFile.createNewFile());
 		assertTrue(libDir.mkdirs());
 		assertTrue(libFile.createNewFile());
 		assertTrue(sharedPrefsDir.mkdirs());
@@ -130,8 +155,6 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 
 		assertFalse(dbDir.exists());
 		assertFalse(keyDir.exists());
-		assertTrue(codeCacheDir.exists());
-		assertTrue(codeCacheFile.exists());
 		assertTrue(libDir.exists());
 		assertTrue(libFile.exists());
 		assertTrue(sharedPrefsDir.exists());

bramble-android/witness.gradle

@@ -1,46 +1,44 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:26.5.1:protos-26.5.1.jar:8dde1130725461fe827f2a343d353f2b51e8870661fc860d7d5ebddb097ead4e',
+        'com.android.tools.analytics-library:protos:26.4.0:protos-26.4.0.jar:ad760915586797d39319f402837b378bff3bb4ed583e3e0c48c965631fb2135f',
-        'com.android.tools.analytics-library:shared:26.5.1:shared-26.5.1.jar:ccc2f3b00ec17b11401610ba68553544fc8fc517120e84439ac6eb86b875e18d',
+        'com.android.tools.analytics-library:shared:26.4.0:shared-26.4.0.jar:1332106a905d48909c81268c9e414946de3e83487db394c6073b0a9b5c3d0ed2',
-        'com.android.tools.analytics-library:tracker:26.5.1:tracker-26.5.1.jar:3a76984c0fe2e847ca7a8b35b4780ef0447a9d1666946cb8e60466318e0ab5ae',
+        'com.android.tools.analytics-library:tracker:26.4.0:tracker-26.4.0.jar:d0020cfbfd4cd75935f2972d6a24089840d4a10df6f3ef2a796093217dd37796',
-        'com.android.tools.build:aapt2-proto:0.4.0:aapt2-proto-0.4.0.jar:fac0435e08898f89eeeb9ca236bea707155ff816c12205ced285ad53604133ca',
+        'com.android.tools.build:apksig:3.4.0:apksig-3.4.0.jar:91d5a1866139c69756280355a6f61b4d619d0516841580114f45a10f2177327e',
-        'com.android.tools.build:apksig:3.5.1:apksig-3.5.1.jar:1fd33e7f009a2a0da766cfeec4211a09f548034b015c289a66d75dd8a9302f4a',
+        'com.android.tools.build:apkzlib:3.4.0:apkzlib-3.4.0.jar:8653c85f5fdf1dde840e8b8af7396aeb79c34b66e541b5860059616006535592',
-        'com.android.tools.build:apkzlib:3.5.1:apkzlib-3.5.1.jar:9f330167cbe973b7db407692f74f4f6453b7ffa5f2048934b06280c2ceee60fa',
+        'com.android.tools.build:builder-model:3.4.0:builder-model-3.4.0.jar:a88f138124a9f016a70bcb4760359a502f65c7deed56507ee4014f4dd9ea853b',
-        'com.android.tools.build:builder-model:3.5.1:builder-model-3.5.1.jar:39ea3c82b76b6e0c9f9fa88d93e0edc1dd4a0f1dfae0ef6fbf2d451da47e5450',
+        'com.android.tools.build:builder-test-api:3.4.0:builder-test-api-3.4.0.jar:31089ab1ec19ca7687a010867d2f3807513c805b8226979706f4247b5d4df26f',
-        'com.android.tools.build:builder-test-api:3.5.1:builder-test-api-3.5.1.jar:a1b59305584cbcaa078fdc9cfb80871012755b822dd32e8da19add6f7bbcb762',
+        'com.android.tools.build:builder:3.4.0:builder-3.4.0.jar:476221b5203a7f50089bf185ed95000a34b6f5020ef0a17815afd58606922679',
-        'com.android.tools.build:builder:3.5.1:builder-3.5.1.jar:e3a8d382434c5f60990730c4719fc814e85a898a33a1e96c1df8d627d3c6eea6',
+        'com.android.tools.build:gradle-api:3.4.0:gradle-api-3.4.0.jar:215eca38f6719213c2f492b4d622cdd11676c66c9871f8a2aed0c66d00175628',
-        'com.android.tools.build:gradle-api:3.5.1:gradle-api-3.5.1.jar:be9b41859bace11998f66b04ed944f87e413f3ad6da3c4665587699da125addc',
+        'com.android.tools.build:manifest-merger:26.4.0:manifest-merger-26.4.0.jar:29e45e690dedd165035e97c21c2ca94d0bd4ec16b6b210daa26669a582b6f220',
-        'com.android.tools.build:manifest-merger:26.5.1:manifest-merger-26.5.1.jar:dcad9ecb967251f4d750f55a4204a2b400e8fbfe5cb930a1d0d5dbe10ae8bdfc',
+        'com.android.tools.ddms:ddmlib:26.4.0:ddmlib-26.4.0.jar:93f56fe4630c3166adbd6c51d7bb602d96abb91b07ba5b1165fdcd071e88c940',
-        'com.android.tools.ddms:ddmlib:26.5.1:ddmlib-26.5.1.jar:b081aef2a4ed3f4d47cae4cdb128469735f25a114e026d37123bf9ffdec742a8',
+        'com.android.tools.external.com-intellij:intellij-core:26.4.0:intellij-core-26.4.0.jar:30cb0e879d4424de9677a50b537fb628636b4a50f5470af5e52437980c41421f',
-        'com.android.tools.external.com-intellij:intellij-core:26.5.1:intellij-core-26.5.1.jar:20eced30adc124805bd93488d9cd9d3e33e6bf7b48e9fe5a703d4983f894d450',
+        'com.android.tools.external.com-intellij:kotlin-compiler:26.4.0:kotlin-compiler-26.4.0.jar:dd1fe225c31a0e012dc025336363a5b783e2c5c20ffb69e77f8f57e89420d998',
-        'com.android.tools.external.com-intellij:kotlin-compiler:26.5.1:kotlin-compiler-26.5.1.jar:5aed762dd54875b77ae7018d97c05756ff0c5b9fd02ec595dd396ccd14cc22cb',
+        'com.android.tools.external.org-jetbrains:uast:26.4.0:uast-26.4.0.jar:f25f3285b775a983327583ff6584dea54e447813ef69e0ce08b05a45b5f4aab0',
-        'com.android.tools.external.org-jetbrains:uast:26.5.1:uast-26.5.1.jar:4bc8653d6c0943f40fee963a149e36c6baa45683d2530968a13f5007e3c40740',
+        'com.android.tools.layoutlib:layoutlib-api:26.4.0:layoutlib-api-26.4.0.jar:52128f5cf293b224072be361919bfd416e59480ab7264ddcdbbf046b0d7a12e3',
-        'com.android.tools.layoutlib:layoutlib-api:26.5.1:layoutlib-api-26.5.1.jar:88732f11396c427273e515d23042e35633f4fe4295528a99b866aa2adf0efd9c',
+        'com.android.tools.lint:lint-api:26.4.0:lint-api-26.4.0.jar:fdb8fca8ae4c254f438338d03d72605e00ed106f2d5550405af41ca1c8509401',
-        'com.android.tools.lint:lint-api:26.5.1:lint-api-26.5.1.jar:ec33fcd72bfaf70dd841e03fbfd93f109c2e575aec146067c606689c3972f0de',
+        'com.android.tools.lint:lint-checks:26.4.0:lint-checks-26.4.0.jar:4ff52d40488cd3e22b9c6b2eb67784e0c3269d0b42ef9d17689cd75a7b2bceb4',
-        'com.android.tools.lint:lint-checks:26.5.1:lint-checks-26.5.1.jar:a1b9607d484aaae7a71dcecdc76f8003d8239af226c776894a2cf63f9e6c60d7',
+        'com.android.tools.lint:lint-gradle-api:26.4.0:lint-gradle-api-26.4.0.jar:714b7a85c7d2aa10daeab16e969fe7530c659d0728a7f24021da456870418d0f',
-        'com.android.tools.lint:lint-gradle-api:26.5.1:lint-gradle-api-26.5.1.jar:82453fd98a8394cc84ed995c04d2cd744abd1d6589403427ba7eef53115406f3',
+        'com.android.tools.lint:lint-gradle:26.4.0:lint-gradle-26.4.0.jar:b8c130d273f522388734457e1b96790f41528fcec6fda9e8eaa4e4d95a07cfbb',
-        'com.android.tools.lint:lint-gradle:26.5.1:lint-gradle-26.5.1.jar:59465b56cf7db77c656d5f8195d721c3d48b6bdd0502d774de335bfe4baff00b',
+        'com.android.tools.lint:lint:26.4.0:lint-26.4.0.jar:83aa062fb0405b60ed358d858c8c2955e1bae44a455b498068c6a60988755f00',
-        'com.android.tools.lint:lint:26.5.1:lint-26.5.1.jar:336e4b04ec6f8b0f25879131b7a7862d77df83a1879ee5b71be26128755f8e2e',
+        'com.android.tools:annotations:26.4.0:annotations-26.4.0.jar:a7955b8e19c3a2a861d6faa43a58b7c0d46ea9112188ee3e235c6f9f439ecc1a',
-        'com.android.tools:annotations:26.5.1:annotations-26.5.1.jar:2c43c82f8c59d8f7a61e3239e1a2dc9f69dc342ec09af9b7c9f69b25337c0b6e',
+        'com.android.tools:common:26.4.0:common-26.4.0.jar:ea40b94b3c1284ea7700f011388e2906a8363a66abd902891722b3c557984852',
-        'com.android.tools:common:26.5.1:common-26.5.1.jar:eccfa54486ed54c4e3123cc42195d023bd0dd21bcd2f0e4868e8c6fc70f8ef6b',
+        'com.android.tools:dvlib:26.4.0:dvlib-26.4.0.jar:23af89c535b01ba36ceed1b6b309b672814eba624e643cd7dedf0519edad50cc',
-        'com.android.tools:dvlib:26.5.1:dvlib-26.5.1.jar:46f93ad498b4756e7d867d2fe38c38890a80e7407a4ae459e4a8c8d5c5aeacfe',
+        'com.android.tools:repository:26.4.0:repository-26.4.0.jar:3d1763ab46199374dc6d94129bba11c70f1d5857e2c81a3ac4898abca40b176b',
-        'com.android.tools:repository:26.5.1:repository-26.5.1.jar:2b3ee791aa4c3e8ce60498c161a27ca7228816fc630eed4d9f25f2f36a106dce',
+        'com.android.tools:sdk-common:26.4.0:sdk-common-26.4.0.jar:78a522525b30ffc6b7bf1299c831d24ce385f68a9f4878f8f752e9baefa31b0f',
-        'com.android.tools:sdk-common:26.5.1:sdk-common-26.5.1.jar:365f749676c3574676fd465177c8a492f340816db2b520d6ed114d3b6e77bea7',
+        'com.android.tools:sdklib:26.4.0:sdklib-26.4.0.jar:b854c23892013a326d761cf071c72cf3e038ed0469d10f4a356829fa56e4c132',
-        'com.android.tools:sdklib:26.5.1:sdklib-26.5.1.jar:007da104afb27c8c682a1628023fe9ec438249c8d15ef0fd6624c5bb8e23b696',
+        'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.code.gson:gson:2.8.5:gson-2.8.5.jar:233a0149fc365c9f6edbd683cfe266b19bdc773be98eabdaf6b3c924b48e7d81',
+        'com.google.code.gson:gson:2.8.0:gson-2.8.0.jar:c6221763bd79c4f1c3dc7f750b5f29a0bb38b367b81314c4f71896e340c40825',
-        'com.google.dagger:dagger-compiler:2.24:dagger-compiler-2.24.jar:3c5afb955fb188da485cb2c048eff37dce0e1530b9780a0f2f7187d16d1ccc1f',
+        'com.google.dagger:dagger-compiler:2.22.1:dagger-compiler-2.22.1.jar:e5f28302cbe70a79d3620cddebfb8ec0736814f3980ffe1e673bfe3342f507d3',
-        'com.google.dagger:dagger-producers:2.24:dagger-producers-2.24.jar:f10f45b95191954d5d6b043fca9e62fb621d21bf70634b8f8476c7988b504c3a',
+        'com.google.dagger:dagger-producers:2.22.1:dagger-producers-2.22.1.jar:f834a0082014213a68ff06a0f048d750178d02196c58b0b15beb367d32b97e35',
-        'com.google.dagger:dagger-spi:2.24:dagger-spi-2.24.jar:c038445d14dbcb4054e61bf49e05009edf26fce4fdc7ec1a9db544784f68e718',
+        'com.google.dagger:dagger-spi:2.22.1:dagger-spi-2.22.1.jar:4b0b922793b3bcb91b99fabb75dba77c68afd7ae4c5f0c4fd6ba681f0a291c7d',
-        'com.google.dagger:dagger:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
+        'com.google.dagger:dagger:2.22.1:dagger-2.22.1.jar:329d4340f24c4f5717af016c097e90668bfea2a5376e6aa9964b01cef3fd241a',
-        'com.google.errorprone:error_prone_annotations:2.2.0:error_prone_annotations-2.2.0.jar:6ebd22ca1b9d8ec06d41de8d64e0596981d9607b42035f9ed374f9de271a481a',
+        '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:failureaccess:1.0.1:failureaccess-1.0.1.jar:a171ee4c734dd2da837e4b16be9df4661afab72a41adaf31eb84dfdaf936ca26',
+        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
-        'com.google.guava:guava:27.0.1-jre:guava-27.0.1-jre.jar:e1c814fd04492a27c38e0317eabeaa1b3e950ec8010239e400fe90ad6c9107b4',
+        'com.google.guava:guava:26.0-jre:guava-26.0-jre.jar:a0e9cabad665bc20bcd2b01f108e5fc03f756e13aea80abaadb9f407033bea2c',
-        'com.google.guava:guava:27.1-jre:guava-27.1-jre.jar:4a5aa70cc968a4d137e599ad37553e5cfeed2265e8c193476d7119036c536fe7',
-        'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava:listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
         'com.google.protobuf:protobuf-java:3.4.0:protobuf-java-3.4.0.jar:dce7e66b32456a1b1198da0caff3a8acb71548658391e798c79369241e6490a4',
@@ -57,7 +55,6 @@ dependencyVerification {
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
         'javax.xml.bind:jaxb-api:2.2.12-b140109.1041:jaxb-api-2.2.12-b140109.1041.jar:b5e60cd8b7b5ff01ce4a74c5dd008f4fbd14ced3495d0b47b85cfedc182211f2',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
-        'net.ltgt.gradle.incap:incap:0.2:incap-0.2.jar:b625b9806b0f1e4bc7a2e3457119488de3cd57ea20feedd513db070a573a4ffd',
         'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
         'net.sf.kxml:kxml2:2.3.0:kxml2-2.3.0.jar:f264dd9f79a1fde10ce5ecc53221eff24be4c9331c830b7d52f2f08a7b633de2',
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
@@ -69,22 +66,22 @@ 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:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
+        'org.briarproject:obfs4proxy-android:0.0.9:obfs4proxy-android-0.0.9.zip:9b7e9181535ea8d8bbe8ae6338e08cf4c5fc1e357a779393e0ce49586d459ae0',
-        'org.briarproject:tor-android:0.3.5.10:tor-android-0.3.5.10.zip:edd83bf557fcff2105eaa0bdb3f607a6852ebe7360920929ae3039dd5f4774c5',
+        'org.briarproject:tor-android:0.3.5.8:tor-android-0.3.5.8.zip:42a13a6f185be1a62f42e3f30ce66a3c099ac5ec890a65e7593111b65b44a54a',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
-        'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
+        'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
         'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
         'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.50:kotlin-reflect-1.3.50.jar:64583199ea5a54aefd1bd1595288925f784226ee562d1dd279011c6075b3d7a4',
+        'org.jetbrains.kotlin:kotlin-reflect:1.3.21:kotlin-reflect-1.3.21.jar:a3065c822633191e0a3e3ee12a29bec234fc4b2864a6bb87ef48cce3e9e0c26a',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.50:kotlin-stdlib-common-1.3.50.jar:8ce678e88e4ba018b66dacecf952471e4d7dfee156a8a819760a5a5ff29d323c',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.21:kotlin-stdlib-common-1.3.21.jar:cea61f7b611895e64f58569a9757fc0ab0d582f107211e1930e0ce2a0add52a7',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.50:kotlin-stdlib-jdk7-1.3.50.jar:9a026639e76212f8d57b86d55b075394c2e009f1979110751d34c05c5f75d57b',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.21:kotlin-stdlib-jdk7-1.3.21.jar:a87875604fd42140da6938ae4d35ee61081f4482536efc6d2615b8b626a198af',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.50:kotlin-stdlib-jdk8-1.3.50.jar:1b351fb6e09c14b55525c74c1f4cf48942eae43c348b7bc764a5e6e423d4da0c',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.21:kotlin-stdlib-jdk8-1.3.21.jar:5823ed66ac122a1c55442ebca5a209a843ccd87f562edc31a787f3d2e47f74d4',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.50:kotlin-stdlib-1.3.50.jar:e6f05746ee0366d0b52825a090fac474dcf44082c9083bbb205bd16976488d6c',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.3.21:kotlin-stdlib-1.3.21.jar:38ba2370d9f06f50433e06b2ca775b94473c2e2785f410926079ab793c72b034',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',

bramble-api/build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.24"
+	implementation "com.google.dagger:dagger:2.22.1"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
 	testImplementation 'junit:junit:4.12'

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

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

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

@@ -1,9 +0,0 @@
-package org.briarproject.bramble.api;
-
-/**
- * Interface for specifying which features are enabled in a build.
- */
-public interface FeatureFlags {
-
-	boolean shouldEnableImageAttachments();
-}

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

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

bramble-api/src/main/java/org/briarproject/bramble/api/account/AccountManager.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.api.account;
 
-import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -14,8 +13,7 @@ public interface AccountManager {
 	 * Returns true if the manager has the database key. This will be false
 	 * before {@link #createAccount(String, String)} or {@link #signIn(String)}
 	 * has been called, and true after {@link #createAccount(String, String)}
-	 * or {@link #signIn(String)} has returned true, until
+	 * or {@link #signIn(String)} has returned true, until the process exits.
-	 * {@link #deleteAccount()} is called or the process exits.
 	 */
 	boolean hasDatabaseKey();
 
@@ -24,22 +22,25 @@ public interface AccountManager {
 	 * before {@link #createAccount(String, String)} or {@link #signIn(String)}
 	 * has been called, and non-null after
 	 * {@link #createAccount(String, String)} or {@link #signIn(String)} has
-	 * returned true, until {@link #deleteAccount()} is called or the process
+	 * returned true, until the process exits.
-	 * exits.
 	 */
 	@Nullable
 	SecretKey getDatabaseKey();
 
 	/**
-	 * Returns true if the encrypted database key can be loaded from disk.
+	 * Returns true if the encrypted database key can be loaded from disk, and
+	 * the database directory exists and is a directory.
 	 */
 	boolean accountExists();
 
 	/**
 	 * Creates an identity with the given name and registers it with the
 	 * {@link IdentityManager}. Creates a database key, encrypts it with the
-	 * given password and stores it on disk. {@link #accountExists()} will
+	 * given password and stores it on disk.
-	 * return true after this method returns true.
+	 * <p/>
+	 * This method does not create the database directory, so
+	 * {@link #accountExists()} will continue to return false until the
+	 * database directory is created.
 	 */
 	boolean createAccount(String name, String password);
 
@@ -53,19 +54,17 @@ public interface AccountManager {
 	 * Loads the encrypted database key from disk and decrypts it with the
 	 * given password.
 	 *
-	 * @throws DecryptionException If the database key could not be loaded and
+	 * @return true if the database key was successfully loaded and decrypted.
-	 * decrypted.
 	 */
-	void signIn(String password) throws DecryptionException;
+	boolean signIn(String password);
 
 	/**
 	 * Loads the encrypted database key from disk, decrypts it with the old
 	 * password, encrypts it with the new password, and stores it on disk,
 	 * replacing the old key.
 	 *
-	 * @throws DecryptionException If the database key could not be loaded and
+	 * @return true if the database key was successfully loaded, re-encrypted
-	 * decrypted.
+	 * and stored.
 	 */
-	void changePassword(String oldPassword, String newPassword)
+	boolean changePassword(String oldPassword, String newPassword);
-			throws DecryptionException;
 }

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

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

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

@@ -1,49 +0,0 @@
-package org.briarproject.bramble.api.connection;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.PendingContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.TransportConnectionReader;
-import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-
-@NotNullByDefault
-public interface ConnectionManager {
-
-	/**
-	 * Manages an incoming connection from a contact over a simplex transport.
-	 */
-	void manageIncomingConnection(TransportId t, TransportConnectionReader r);
-
-	/**
-	 * Manages an incoming connection from a contact over a duplex transport.
-	 */
-	void manageIncomingConnection(TransportId t, DuplexTransportConnection d);
-
-	/**
-	 * Manages an incoming handshake connection from a pending contact over a
-	 * duplex transport.
-	 */
-	void manageIncomingConnection(PendingContactId p, TransportId t,
-			DuplexTransportConnection d);
-
-	/**
-	 * Manages an outgoing connection to a contact over a simplex transport.
-	 */
-	void manageOutgoingConnection(ContactId c, TransportId t,
-			TransportConnectionWriter w);
-
-	/**
-	 * Manages an outgoing connection to a contact over a duplex transport.
-	 */
-	void manageOutgoingConnection(ContactId c, TransportId t,
-			DuplexTransportConnection d);
-
-	/**
-	 * Manages an outgoing handshake connection to a pending contact over a
-	 * duplex transport.
-	 */
-	void manageOutgoingConnection(PendingContactId p, TransportId t,
-			DuplexTransportConnection d);
-}

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

@@ -1,130 +0,0 @@
-package org.briarproject.bramble.api.connection;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.PendingContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginConfig;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
-import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
-import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
-import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
-import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionClosedEvent;
-import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionOpenedEvent;
-import org.briarproject.bramble.api.sync.Priority;
-
-import java.util.Collection;
-
-/**
- * Keeps track of which contacts are currently connected by which transports.
- */
-@NotNullByDefault
-public interface ConnectionRegistry {
-
-	/**
-	 * Registers an incoming connection from the given contact over the given
-	 * transport. The connection's {@link Priority priority} can be set later
-	 * via {@link #setPriority(ContactId, TransportId, InterruptibleConnection,
-	 * Priority)} if a priority record is received from the contact.
-	 * <p>
-	 * Broadcasts {@link ConnectionOpenedEvent}. Also broadcasts
-	 * {@link ContactConnectedEvent} if this is the only connection with the
-	 * contact.
-	 */
-	void registerIncomingConnection(ContactId c, TransportId t,
-			InterruptibleConnection conn);
-
-	/**
-	 * Registers an outgoing connection to the given contact over the given
-	 * transport.
-	 * <p>
-	 * Broadcasts {@link ConnectionOpenedEvent}. Also broadcasts
-	 * {@link ContactConnectedEvent} if this is the only connection with the
-	 * contact.
-	 * <p>
-	 * If the registry has any "better" connections with the given contact, the
-	 * given connection will be interrupted. If the registry has any "worse"
-	 * connections with the given contact, those connections will be
-	 * interrupted.
-	 * <p>
-	 * Connection A is considered "better" than connection B if both
-	 * connections have had their priorities set, and either A's transport is
-	 * {@link PluginConfig#getTransportPreferences() preferred} to B's, or
-	 * they use the same transport and A has higher {@link Priority priority}
-	 * than B.
-	 * <p>
-	 * For backward compatibility, connections without priorities are not
-	 * considered better or worse than other connections.
-	 */
-	void registerOutgoingConnection(ContactId c, TransportId t,
-			InterruptibleConnection conn, Priority priority);
-
-	/**
-	 * Unregisters a connection with the given contact over the given transport.
-	 * <p>
-	 * Broadcasts {@link ConnectionClosedEvent}. Also broadcasts
-	 * {@link ContactDisconnectedEvent} if this is the only connection with
-	 * the contact.
-	 */
-	void unregisterConnection(ContactId c, TransportId t,
-			InterruptibleConnection conn, boolean incoming, boolean exception);
-
-	/**
-	 * Sets the {@link Priority priority} of a connection that was previously
-	 * registered via {@link #registerIncomingConnection(ContactId, TransportId,
-	 * InterruptibleConnection)}.
-	 * <p>
-	 * If the registry has any "better" connections with the given contact, the
-	 * given connection will be interrupted. If the registry has any "worse"
-	 * connections with the given contact, those connections will be
-	 * interrupted.
-	 * <p>
-	 * Connection A is considered "better" than connection B if both
-	 * connections have had their priorities set, and either A's transport is
-	 * {@link PluginConfig#getTransportPreferences() preferred} to B's, or
-	 * they use the same transport and A has higher {@link Priority priority}
-	 * than B.
-	 * <p>
-	 * For backward compatibility, connections without priorities are not
-	 * considered better or worse than other connections.
-	 */
-	void setPriority(ContactId c, TransportId t, InterruptibleConnection conn,
-			Priority priority);
-
-	/**
-	 * Returns any contacts that are connected via the given transport.
-	 */
-	Collection<ContactId> getConnectedContacts(TransportId t);
-
-	/**
-	 * Returns any contacts that are connected via the given transport or any
-	 * {@link PluginConfig#getTransportPreferences() better} transport.
-	 */
-	Collection<ContactId> getConnectedOrBetterContacts(TransportId t);
-
-	/**
-	 * Returns true if the given contact is connected via the given transport.
-	 */
-	boolean isConnected(ContactId c, TransportId t);
-
-	/**
-	 * Returns true if the given contact is connected via any transport.
-	 */
-	boolean isConnected(ContactId c);
-
-	/**
-	 * Registers a connection with the given pending contact. Broadcasts
-	 * {@link RendezvousConnectionOpenedEvent} if this is the only connection
-	 * with the pending contact.
-	 *
-	 * @return True if this is the only connection with the pending contact,
-	 * false if it is redundant and should be closed
-	 */
-	boolean registerConnection(PendingContactId p);
-
-	/**
-	 * Unregisters a connection with the given pending contact. Broadcasts
-	 * {@link RendezvousConnectionClosedEvent}.
-	 */
-	void unregisterConnection(PendingContactId p, boolean success);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/connection/InterruptibleConnection.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.api.connection;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-/**
- * A duplex sync connection that can be closed by interrupting its outgoing
- * sync session.
- */
-@NotNullByDefault
-public interface InterruptibleConnection {
-
-	/**
-	 * Interrupts the connection's outgoing sync session. If the underlying
-	 * transport connection is alive and the remote peer is cooperative, this
-	 * should result in both sync sessions ending and the connection being
-	 * cleanly closed.
-	 */
-	void interruptOutgoingSession();
-}

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.api.contact;
 
-import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -9,6 +8,7 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.toUtf8;
 
 @Immutable
@@ -21,17 +21,21 @@ public class Contact {
 	@Nullable
 	private final String alias;
 	@Nullable
-	private final PublicKey handshakePublicKey;
+	private final byte[] handshakePublicKey;
 	private final boolean verified;
 
 	public Contact(ContactId id, Author author, AuthorId localAuthorId,
-			@Nullable String alias, @Nullable PublicKey handshakePublicKey,
+			@Nullable String alias, @Nullable byte[] handshakePublicKey,
 			boolean verified) {
 		if (alias != null) {
 			int aliasLength = toUtf8(alias).length;
 			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
 				throw new IllegalArgumentException();
 		}
+		if (handshakePublicKey != null && (handshakePublicKey.length == 0 ||
+				handshakePublicKey.length > MAX_PUBLIC_KEY_LENGTH)) {
+			throw new IllegalArgumentException();
+		}
 		this.id = id;
 		this.author = author;
 		this.localAuthorId = localAuthorId;
@@ -58,7 +62,7 @@ public class Contact {
 	}
 
 	@Nullable
-	public PublicKey getHandshakePublicKey() {
+	public byte[] getHandshakePublicKey() {
 		return handshakePublicKey;
 	}
 

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

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

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

@@ -1,6 +1,16 @@
-package org.briarproject.bramble.contact;
+package org.briarproject.bramble.api.contact;
 
-interface ContactExchangeConstants {
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+/**
+ * A task for conducting a contact information exchange with a remote peer.
+ */
+@NotNullByDefault
+public interface ContactExchangeTask {
 
 	/**
 	 * The current version of the contact exchange protocol.
@@ -29,7 +39,9 @@ interface ContactExchangeConstants {
 	String BOB_NONCE_LABEL = "org.briarproject.bramble.contact/BOB_NONCE";
 
 	/**
-	 * Label for signing key binding nonces.
+	 * Exchanges contact information with a remote peer.
 	 */
-	String SIGNING_LABEL = "org.briarproject.briar.contact/EXCHANGE";
+	void startExchange(LocalAuthor localAuthor, SecretKey masterKey,
+			DuplexTransportConnection conn, TransportId transportId,
+			boolean alice);
 }

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

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

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

@@ -1,13 +1,10 @@
 package org.briarproject.bramble.api.contact;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
-import org.briarproject.bramble.api.db.PendingContactExistsException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
@@ -15,7 +12,6 @@ import org.briarproject.bramble.api.identity.AuthorInfo;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
-import java.security.GeneralSecurityException;
 import java.util.Collection;
 
 import javax.annotation.Nullable;
@@ -32,71 +28,28 @@ public interface ContactManager {
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores rotation mode transport keys for each transport, and
+	 * derives and stores transport keys for each transport, and returns an ID
-	 * returns an ID for the contact.
+	 * for the contact.
 	 *
-	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param alice true if the local party is Alice
-	 * @param timestamp The timestamp for deriving rotation mode transport
-	 * keys from the root key
-	 * @param alice True if the local party is Alice
-	 * @param verified True if the contact's identity has been verified, which
-	 * is true if the contact was added in person or false if the contact was
-	 * introduced or added remotely
-	 * @param active True if the rotation mode transport keys can be used for
-	 * outgoing streams
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
 			SecretKey rootKey, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
-	/**
-	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * replacing the given pending contact, derives and stores handshake mode
-	 * and rotation mode transport keys for each transport, and returns an ID
-	 * for the contact.
-	 *
-	 * @param rootKey The root key for a set of rotation mode transport keys
-	 * @param timestamp The timestamp for deriving rotation mode transport
-	 * keys from the root key
-	 * @param alice True if the local party is Alice
-	 * @param verified True if the contact's identity has been verified, which
-	 * is true if the contact was added in person or false if the contact was
-	 * introduced or added remotely
-	 * @param active True if the rotation mode transport keys can be used for
-	 * outgoing streams
-	 * @throws GeneralSecurityException If the pending contact's handshake
-	 * public key is invalid
-	 */
-	ContactId addContact(Transaction txn, PendingContactId p, Author remote,
-			AuthorId local, SecretKey rootKey, long timestamp, boolean alice,
-			boolean verified, boolean active)
-			throws DbException, GeneralSecurityException;
-
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms
 	 * and returns an ID for the contact.
-	 *
-	 * @param verified True if the contact's identity has been verified, which
-	 * is true if the contact was added in person or false if the contact was
-	 * introduced or added remotely
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
 			boolean verified) throws DbException;
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores rotation mode transport keys for each transport, and
+	 * derives and stores transport keys for each transport, and returns an ID
-	 * returns an ID for the contact.
+	 * for the contact.
 	 *
-	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param alice true if the local party is Alice
-	 * @param timestamp The timestamp for deriving rotation mode transport
-	 * keys from the root key
-	 * @param alice True if the local party is Alice
-	 * @param verified True if the contact's identity has been verified, which
-	 * is true if the contact was added in person or false if the contact was
-	 * introduced or added remotely
-	 * @param active True if the rotation mode transport keys can be used for
-	 * outgoing streams
 	 */
 	ContactId addContact(Author remote, AuthorId local, SecretKey rootKey,
 			long timestamp, boolean alice, boolean verified, boolean active)
@@ -112,34 +65,20 @@ public interface ContactManager {
 	 * Creates a {@link PendingContact} from the given handshake link and
 	 * alias, adds it to the database and returns it.
 	 *
-	 * @param link The handshake link received from the pending contact
+	 * @param link The handshake link received from the contact we want to add
-	 * @param alias The alias the user has given this pending contact
+	 * @param alias The alias the user has given this contact
+	 * @return A PendingContact representing the contact to be added
 	 * @throws UnsupportedVersionException If the link uses a format version
 	 * that is not supported
 	 * @throws FormatException If the link is invalid
-	 * @throws GeneralSecurityException If the pending contact's handshake
-	 * public key is invalid
-	 * @throws ContactExistsException If a contact with the same handshake
-	 * public key already exists
-	 * @throws PendingContactExistsException If a pending contact with the same
-	 * handshake public key already exists
 	 */
 	PendingContact addPendingContact(String link, String alias)
-			throws DbException, FormatException, GeneralSecurityException,
+			throws DbException, FormatException;
-			ContactExistsException, PendingContactExistsException;
 
 	/**
-	 * Returns the pending contact with the given ID.
+	 * Returns a list of {@link PendingContact}s.
 	 */
-	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+	Collection<PendingContact> getPendingContacts() throws DbException;
-			throws DbException;
-
-	/**
-	 * Returns a list of {@link PendingContact PendingContacts} and their
-	 * {@link PendingContactState states}.
-	 */
-	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
-			throws DbException;
 
 	/**
 	 * Removes a {@link PendingContact}.
@@ -152,13 +91,8 @@ public interface ContactManager {
 	Contact getContact(ContactId c) throws DbException;
 
 	/**
-	 * Returns the contact with the given ID.
+	 * Returns the contact with the given remoteAuthorId
-	 */
+	 * that was added by the LocalAuthor with the given localAuthorId
-	Contact getContact(Transaction txn, ContactId c) throws DbException;
-
-	/**
-	 * Returns the contact with the given {@code remoteAuthorId}
-	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
 	 *
 	 * @throws NoSuchContactException If the contact is not in the database
 	 */
@@ -166,8 +100,8 @@ public interface ContactManager {
 			throws DbException;
 
 	/**
-	 * Returns the contact with the given {@code remoteAuthorId}
+	 * Returns the contact with the given remoteAuthorId
-	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
+	 * that was added by the LocalAuthor with the given localAuthorId
 	 *
 	 * @throws NoSuchContactException If the contact is not in the database
 	 */
@@ -175,7 +109,7 @@ public interface ContactManager {
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Returns all contacts.
+	 * Returns all active contacts.
 	 */
 	Collection<Contact> getContacts() throws DbException;
 
@@ -190,27 +124,25 @@ public interface ContactManager {
 	void removeContact(Transaction txn, ContactId c) throws DbException;
 
 	/**
-	 * Sets an alias for the contact or unsets it if {@code alias} is null.
+	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */
 	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Sets an alias for the contact or unsets it if {@code alias} is null.
+	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */
 	void setContactAlias(ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * Return true if a contact with this name and public key already exists
-	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * Return true if a contact with this name and public key already exists
-	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;

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

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

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

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

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

@@ -3,7 +3,6 @@ package org.briarproject.bramble.api.contact;
 import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -18,8 +17,9 @@ public class PendingContactId extends UniqueId {
 		super(id);
 	}
 
+
 	@Override
-	public boolean equals(@Nullable Object o) {
+	public boolean equals(Object o) {
 		return o instanceof PendingContactId && super.equals(o);
 	}
 }

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

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

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

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

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

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

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

@@ -0,0 +1,22 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class ContactAddedRemotelyEvent extends Event {
+
+	private final Contact contact;
+
+	public ContactAddedRemotelyEvent(Contact contact) {
+		this.contact = contact;
+	}
+
+	public Contact getContact() {
+		return contact;
+	}
+}

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

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

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

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

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

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

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

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

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

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

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

@@ -27,78 +27,54 @@ public interface CryptoComponent {
 	/**
 	 * Derives another secret key from the given secret key.
 	 *
-	 * @param label A namespaced label indicating the purpose of the derived
+	 * @param label a namespaced label indicating the purpose of the derived
 	 * key, to prevent it from being repurposed or colliding with a key derived
 	 * for another purpose
-	 * @param inputs Additional inputs that will be included in the derivation
-	 * of the key
 	 */
 	SecretKey deriveKey(String label, SecretKey k, byte[]... inputs);
 
 	/**
-	 * Derives a shared secret from two key pairs.
+	 * Derives a common shared secret from two public keys and one of the
+	 * corresponding private keys.
 	 *
-	 * @param label A namespaced label indicating the purpose of this shared
+	 * @param label a namespaced label indicating the purpose of this shared
 	 * secret, to prevent it from being repurposed or colliding with a shared
 	 * secret derived for another purpose
-	 * @param theirPublicKey The public key of the remote party
+	 * @param theirPublicKey the public key of the remote party
-	 * @param ourKeyPair The key pair of the local party
+	 * @param ourKeyPair the key pair of the local party
-	 * @param inputs Additional inputs that will be included in the derivation
+	 * @return the shared secret
-	 * of the shared secret
-	 * @return The shared secret
 	 */
 	SecretKey deriveSharedSecret(String label, PublicKey theirPublicKey,
 			KeyPair ourKeyPair, byte[]... inputs)
 			throws GeneralSecurityException;
 
-	/**
-	 * Derives a shared secret from two static and two ephemeral key pairs.
-	 *
-	 * @param label A namespaced label indicating the purpose of this shared
-	 * secret, to prevent it from being repurposed or colliding with a shared
-	 * secret derived for another purpose
-	 * @param theirStaticPublicKey The static public key of the remote party
-	 * @param theirEphemeralPublicKey The ephemeral public key of the remote
-	 * party
-	 * @param ourStaticKeyPair The static key pair of the local party
-	 * @param ourEphemeralKeyPair The ephemeral key pair of the local party
-	 * @param alice True if the local party is Alice
-	 * @param inputs Additional inputs that will be included in the
-	 * derivation of the shared secret
-	 * @return The shared secret
-	 */
-	SecretKey deriveSharedSecret(String label, PublicKey theirStaticPublicKey,
-			PublicKey theirEphemeralPublicKey, KeyPair ourStaticKeyPair,
-			KeyPair ourEphemeralKeyPair, boolean alice, byte[]... inputs)
-			throws GeneralSecurityException;
-
 	/**
 	 * Signs the given byte[] with the given private key.
 	 *
-	 * @param label A namespaced label indicating the purpose of this
+	 * @param label a namespaced label indicating the purpose of this
 	 * signature, to prevent it from being repurposed or colliding with a
 	 * signature created for another purpose
 	 */
-	byte[] sign(String label, byte[] toSign, PrivateKey privateKey)
+	byte[] sign(String label, byte[] toSign, byte[] privateKey)
 			throws GeneralSecurityException;
 
 	/**
 	 * Verifies that the given signature is valid for the signed data
 	 * and the given public key.
 	 *
-	 * @param label A namespaced label indicating the purpose of this
+	 * @param label a namespaced label indicating the purpose of this
 	 * signature, to prevent it from being repurposed or colliding with a
 	 * signature created for another purpose
-	 * @return True if the signature was valid, false otherwise.
+	 * @return true if the signature was valid, false otherwise.
 	 */
 	boolean verifySignature(byte[] signature, String label, byte[] signed,
-			PublicKey publicKey) throws GeneralSecurityException;
+			byte[] publicKey) throws GeneralSecurityException;
 
 	/**
 	 * Returns the hash of the given inputs. The inputs are unambiguously
 	 * combined by prefixing each input with its length.
 	 *
-	 * @param label A namespaced label indicating the purpose of this hash, to
+	 * @param label a namespaced label indicating the purpose of this hash, to
 	 * prevent it from being repurposed or colliding with a hash created for
 	 * another purpose
 	 */
@@ -109,7 +85,7 @@ public interface CryptoComponent {
 	 * given inputs. The inputs are unambiguously combined by prefixing each
 	 * input with its length.
 	 *
-	 * @param label A namespaced label indicating the purpose of this MAC, to
+	 * @param label a namespaced label indicating the purpose of this MAC, to
 	 * prevent it from being repurposed or colliding with a MAC created for
 	 * another purpose
 	 */
@@ -119,10 +95,10 @@ public interface CryptoComponent {
 	 * Verifies that the given message authentication code is valid for the
 	 * given secret key and inputs.
 	 *
-	 * @param label A namespaced label indicating the purpose of this MAC, to
+	 * @param label a namespaced label indicating the purpose of this MAC, to
 	 * prevent it from being repurposed or colliding with a MAC created for
 	 * another purpose
-	 * @return True if the MAC was valid, false otherwise.
+	 * @return true if the MAC was valid, false otherwise.
 	 */
 	boolean verifyMac(byte[] mac, String label, SecretKey macKey,
 			byte[]... inputs);
@@ -132,33 +108,17 @@ public interface CryptoComponent {
 	 * storage. The encryption and authentication keys are derived from the
 	 * given password. The ciphertext will be decryptable using the same
 	 * password after the app restarts.
-	 *
-	 * @param keyStrengthener Used to strengthen the password-based key. If
-	 * null, the password-based key will not be strengthened
 	 */
-	byte[] encryptWithPassword(byte[] plaintext, String password,
+	byte[] encryptWithPassword(byte[] plaintext, String password);
-			@Nullable KeyStrengthener keyStrengthener);
 
 	/**
 	 * Decrypts and authenticates the given ciphertext that has been read from
 	 * storage. The encryption and authentication keys are derived from the
-	 * given password.
+	 * given password. Returns null if the ciphertext cannot be decrypted and
-	 *
-	 * @param keyStrengthener Used to strengthen the password-based key. If
-	 * null, or if strengthening was not used when encrypting the ciphertext,
-	 * the password-based key will not be strengthened
-	 * @throws DecryptionException If the ciphertext cannot be decrypted and
 	 * authenticated (for example, if the password is wrong).
 	 */
-	byte[] decryptWithPassword(byte[] ciphertext, String password,
+	@Nullable
-			@Nullable KeyStrengthener keyStrengthener)
+	byte[] decryptWithPassword(byte[] ciphertext, String password);
-			throws DecryptionException;
-
-	/**
-	 * Returns true if the given ciphertext was encrypted using a strengthened
-	 * key. The validity of the ciphertext is not checked.
-	 */
-	boolean isEncryptedWithStrengthenedKey(byte[] ciphertext);
 
 	/**
 	 * Encrypts the given plaintext to the given public key.

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

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

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

@@ -1,17 +0,0 @@
-package org.briarproject.bramble.api.crypto;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public class DecryptionException extends Exception {
-
-	private final DecryptionResult result;
-
-	public DecryptionException(DecryptionResult result) {
-		this.result = result;
-	}
-
-	public DecryptionResult getDecryptionResult() {
-		return result;
-	}
-}

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

@@ -1,29 +0,0 @@
-package org.briarproject.bramble.api.crypto;
-
-/**
- * The result of a password-based decryption operation.
- */
-public enum DecryptionResult {
-
-	/**
-	 * Decryption succeeded.
-	 */
-	SUCCESS,
-
-	/**
-	 * Decryption failed because the format of the ciphertext was invalid.
-	 */
-	INVALID_CIPHERTEXT,
-
-	/**
-	 * Decryption failed because the {@link KeyStrengthener} used for
-	 * encryption was not available for decryption.
-	 */
-	KEY_STRENGTHENER_ERROR,
-
-	/**
-	 * Decryption failed because the password used for decryption did not match
-	 * the password used for encryption.
-	 */
-	INVALID_PASSWORD
-}

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

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

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

@@ -1,23 +0,0 @@
-package org.briarproject.bramble.api.crypto;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-/**
- * Interface for strengthening a password-based key, for example by using a
- * key stored in a key management service or hardware security module.
- */
-@NotNullByDefault
-public interface KeyStrengthener {
-
-	/**
-	 * Returns true if the strengthener has been initialised.
-	 */
-	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
-	boolean isInitialised();
-
-	/**
-	 * Initialises the strengthener if necessary and returns a strong key
-	 * derived from the given key.
-	 */
-	SecretKey strengthenKey(SecretKey k);
-}

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -4,8 +4,6 @@ import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.contact.PendingContactId;
-import org.briarproject.bramble.api.crypto.PrivateKey;
-import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
@@ -24,12 +22,14 @@ import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.validation.MessageState;
-import org.briarproject.bramble.api.transport.KeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeySet;
+import org.briarproject.bramble.api.transport.HandshakeKeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.TransportKeySet;
+import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -39,7 +39,7 @@ import javax.annotation.Nullable;
  * to other components.
  */
 @NotNullByDefault
-public interface DatabaseComponent extends TransactionManager {
+public interface DatabaseComponent {
 
 	/**
 	 * Opens the database and returns true if the database already existed.
@@ -57,18 +57,76 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	void close() throws DbException;
 
+	/**
+	 * Starts a new transaction and returns an object representing it.
+	 * <p/>
+	 * This method acquires locks, so it must not be called while holding a
+	 * lock.
+	 *
+	 * @param readOnly true if the transaction will only be used for reading.
+	 */
+	Transaction startTransaction(boolean readOnly) throws DbException;
+
+	/**
+	 * Commits a transaction to the database.
+	 */
+	void commitTransaction(Transaction txn) throws DbException;
+
+	/**
+	 * Ends a transaction. If the transaction has not been committed,
+	 * it will be aborted. If the transaction has been committed,
+	 * any events attached to the transaction are broadcast.
+	 * The database lock will be released in either case.
+	 */
+	void endTransaction(Transaction txn);
+
+	/**
+	 * Runs the given task within a transaction.
+	 */
+	<E extends Exception> void transaction(boolean readOnly,
+			DbRunnable<E> task) throws DbException, E;
+
+	/**
+	 * Runs the given task within a transaction and returns the result of the
+	 * task.
+	 */
+	<R, E extends Exception> R transactionWithResult(boolean readOnly,
+			DbCallable<R, E> task) throws DbException, E;
+
+	/**
+	 * Runs the given task within a transaction and returns the result of the
+	 * task, which may be null.
+	 */
+	@Nullable
+	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,
+			NullableDbCallable<R, E> task) throws DbException, E;
+
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
 	 * and returns an ID for the contact.
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			@Nullable PublicKey handshake, boolean verified) throws DbException;
+			boolean verified) throws DbException;
 
 	/**
 	 * Stores a group.
 	 */
 	void addGroup(Transaction txn, Group g) throws DbException;
 
+	/**
+	 * Stores the given handshake keys for the given contact and returns a
+	 * key set ID.
+	 */
+	HandshakeKeySetId addHandshakeKeys(Transaction txn, ContactId c,
+			HandshakeKeys k) throws DbException;
+
+	/**
+	 * Stores the given handshake keys for the given pending contact and
+	 * returns a key set ID.
+	 */
+	HandshakeKeySetId addHandshakeKeys(Transaction txn, PendingContactId p,
+			HandshakeKeys k) throws DbException;
+
 	/**
 	 * Stores an identity.
 	 */
@@ -78,12 +136,12 @@ public interface DatabaseComponent extends TransactionManager {
 	 * Stores a local message.
 	 */
 	void addLocalMessage(Transaction txn, Message m, Metadata meta,
-			boolean shared, boolean temporary) throws DbException;
+			boolean shared) throws DbException;
 
 	/**
 	 * Stores a pending contact.
 	 */
-	void addPendingContact(Transaction txn, PendingContact p, AuthorId local)
+	void addPendingContact(Transaction txn, PendingContact p)
 			throws DbException;
 
 	/**
@@ -96,14 +154,7 @@ public interface DatabaseComponent extends TransactionManager {
 	 * Stores the given transport keys for the given contact and returns a
 	 * key set ID.
 	 */
-	KeySetId addTransportKeys(Transaction txn, ContactId c, TransportKeys k)
+	TransportKeySetId addTransportKeys(Transaction txn, ContactId c,
-			throws DbException;
-
-	/**
-	 * Stores the given transport keys for the given pending contact and
-	 * returns a key set ID.
-	 */
-	KeySetId addTransportKeys(Transaction txn, PendingContactId p,
 			TransportKeys k) throws DbException;
 
 	/**
@@ -223,7 +274,7 @@ public interface DatabaseComponent extends TransactionManager {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<ContactId> getContacts(Transaction txn, AuthorId local)
+	Collection<ContactId> getContacts(Transaction txn, AuthorId a)
 			throws DbException;
 
 	/**
@@ -257,6 +308,14 @@ public interface DatabaseComponent extends TransactionManager {
 	Visibility getGroupVisibility(Transaction txn, ContactId c, GroupId g)
 			throws DbException;
 
+	/**
+	 * Returns all handshake keys for the given transport.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<HandshakeKeySet> getHandshakeKeys(Transaction txn, TransportId t)
+			throws DbException;
+
 	/**
 	 * Returns the identity for the local pseudonym with the given ID.
 	 * <p/>
@@ -405,14 +464,6 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
 
-	/**
-	 * Returns the pending contact with the given ID.
-	 * <p/>
-	 * Read-only.
-	 */
-	PendingContact getPendingContact(Transaction txn, PendingContactId p)
-			throws DbException;
-
 	/**
 	 * Returns all pending contacts.
 	 * <p/>
@@ -428,13 +479,6 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	Settings getSettings(Transaction txn, String namespace) throws DbException;
 
-	/**
-	 * Returns the versions of the sync protocol supported by the given contact.
-	 * <p/>
-	 * Read-only.
-	 */
-	List<Byte> getSyncVersions(Transaction txn, ContactId c) throws DbException;
-
 	/**
 	 * Returns all transport keys for the given transport.
 	 * <p/>
@@ -443,11 +487,17 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<TransportKeySet> getTransportKeys(Transaction txn, TransportId t)
 			throws DbException;
 
+	/**
+	 * Increments the outgoing stream counter for the given handshake keys.
+	 */
+	void incrementStreamCounter(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
-	void incrementStreamCounter(Transaction txn, TransportId t, KeySetId k)
+	void incrementStreamCounter(Transaction txn, TransportId t,
-			throws DbException;
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Merges the given metadata with the existing metadata for the given
@@ -502,6 +552,12 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	void removeGroup(Transaction txn, Group g) throws DbException;
 
+	/**
+	 * Removes the given handshake keys from the database.
+	 */
+	void removeHandshakeKeys(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
 	/**
 	 * Removes an identity (and all associated state) from the database.
 	 */
@@ -518,12 +574,6 @@ public interface DatabaseComponent extends TransactionManager {
 	void removePendingContact(Transaction txn, PendingContactId p)
 			throws DbException;
 
-	/**
-	 * Removes all temporary messages (and all associated state) from the
-	 * database.
-	 */
-	void removeTemporaryMessages(Transaction txn) throws DbException;
-
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */
@@ -532,8 +582,8 @@ public interface DatabaseComponent extends TransactionManager {
 	/**
 	 * Removes the given transport keys from the database.
 	 */
-	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
+	void removeTransportKeys(Transaction txn, TransportId t,
-			throws DbException;
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Marks the given contact as verified.
@@ -552,11 +602,6 @@ public interface DatabaseComponent extends TransactionManager {
 	void setGroupVisibility(Transaction txn, ContactId c, GroupId g,
 			Visibility v) throws DbException;
 
-	/**
-	 * Marks the given message as permanent, i.e. not temporary.
-	 */
-	void setMessagePermanent(Transaction txn, MessageId m) throws DbException;
-
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -577,26 +622,35 @@ public interface DatabaseComponent extends TransactionManager {
 	/**
 	 * Sets the handshake key pair for the identity with the given ID.
 	 */
-	void setHandshakeKeyPair(Transaction txn, AuthorId local,
+	void setHandshakeKeyPair(Transaction txn, AuthorId local, byte[] publicKey,
-			PublicKey publicKey, PrivateKey privateKey) throws DbException;
+			byte[] privateKey) throws DbException;
 
 	/**
-	 * Sets the reordering window for the given transport keys in the given
+	 * Sets the reordering window for the given transport key set in the given
 	 * time period.
 	 */
-	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
+	void setReorderingWindow(Transaction txn, TransportKeySetId k,
-			long timePeriod, long base, byte[] bitmap) throws DbException;
+			TransportId t, long timePeriod, long base, byte[] bitmap)
+			throws DbException;
 
 	/**
-	 * Sets the versions of the sync protocol supported by the given contact.
+	 * Sets the reordering window for the given handshake key set in the given
+	 * time period.
 	 */
-	void setSyncVersions(Transaction txn, ContactId c, List<Byte> supported)
+	void setReorderingWindow(Transaction txn, HandshakeKeySetId k,
+			TransportId t, long timePeriod, long base, byte[] bitmap)
 			throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
-	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
+	void setTransportKeysActive(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
+
+	/**
+	 * Stores the given handshake keys, deleting any keys they have replaced.
+	 */
+	void updateHandshakeKeys(Transaction txn, Collection<HandshakeKeySet> keys)
 			throws DbException;
 
 	/**

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

@@ -1,29 +1,13 @@
 package org.briarproject.bramble.api.db;
 
-import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.File;
 
-import javax.annotation.Nullable;
-
 @NotNullByDefault
 public interface DatabaseConfig {
 
-	/**
-	 * Returns the directory where the database stores its data.
-	 */
 	File getDatabaseDirectory();
 
-	/**
-	 * Returns the directory where the encrypted database key is stored.
-	 */
 	File getDatabaseKeyDirectory();
-
-	/**
-	 * Returns a {@link KeyStrengthener} for strengthening the encryption of
-	 * the database key, or null if no strengthener should be used.
-	 */
-	@Nullable
-	KeyStrengthener getKeyStrengthener();
 }

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

@@ -1,21 +1,9 @@
 package org.briarproject.bramble.api.db;
 
-import org.briarproject.bramble.api.contact.PendingContact;
-
 /**
  * Thrown when a duplicate pending contact is added to the database. This
  * exception may occur due to concurrent updates and does not indicate a
  * database error.
  */
 public class PendingContactExistsException extends DbException {
-
-	private final PendingContact pendingContact;
-
-	public PendingContactExistsException(PendingContact pendingContact) {
-		this.pendingContact = pendingContact;
-	}
-
-	public PendingContact getPendingContact() {
-		return pendingContact;
-	}
 }

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

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

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

@@ -18,8 +18,6 @@ public interface EventBus {
 	/**
 	 * Asynchronously notifies all listeners of an event. Listeners are
 	 * notified on the {@link EventExecutor}.
-	 * <p>
-	 * This method can safely be called while holding a lock.
 	 */
 	void broadcast(Event e);
 }

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

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

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.api.identity;
 
-import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 @NotNullByDefault
@@ -10,12 +9,12 @@ public interface AuthorFactory {
 	 * Creates an author with the current format version and the given name and
 	 * public key.
 	 */
-	Author createAuthor(String name, PublicKey publicKey);
+	Author createAuthor(String name, byte[] publicKey);
 
 	/**
 	 * Creates an author with the given format version, name and public key.
 	 */
-	Author createAuthor(int formatVersion, String name, PublicKey publicKey);
+	Author createAuthor(int formatVersion, String name, byte[] publicKey);
 
 	/**
 	 * Creates a local author with the current format version and the given

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

@@ -1,13 +1,13 @@
 package org.briarproject.bramble.api.identity;
 
-import org.briarproject.bramble.api.crypto.PrivateKey;
-import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import java.util.Arrays;
+
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
-import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
+import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_AGREEMENT_PUBLIC_KEY_BYTES;
 
 @Immutable
 @NotNullByDefault
@@ -15,24 +15,15 @@ public class Identity {
 
 	private final LocalAuthor localAuthor;
 	@Nullable
-	private final PublicKey handshakePublicKey;
+	private final byte[] handshakePublicKey, handshakePrivateKey;
-	@Nullable
-	private final PrivateKey handshakePrivateKey;
 	private final long created;
 
 	public Identity(LocalAuthor localAuthor,
-			@Nullable PublicKey handshakePublicKey,
+			@Nullable byte[] handshakePublicKey,
-			@Nullable PrivateKey handshakePrivateKey, long created) {
+			@Nullable byte[] handshakePrivateKey, long created) {
 		if (handshakePublicKey != null) {
-			if (handshakePrivateKey == null)
+			int keyLength = handshakePublicKey.length;
-				throw new IllegalArgumentException();
+			if (keyLength == 0 || keyLength > MAX_AGREEMENT_PUBLIC_KEY_BYTES)
-			if (!handshakePublicKey.getKeyType().equals(KEY_TYPE_AGREEMENT))
-				throw new IllegalArgumentException();
-		}
-		if (handshakePrivateKey != null) {
-			if (handshakePublicKey == null)
-				throw new IllegalArgumentException();
-			if (!handshakePrivateKey.getKeyType().equals(KEY_TYPE_AGREEMENT))
 				throw new IllegalArgumentException();
 		}
 		this.localAuthor = localAuthor;
@@ -66,7 +57,7 @@ public class Identity {
 	 * Returns the public key used for handshaking, or null if no key exists.
 	 */
 	@Nullable
-	public PublicKey getHandshakePublicKey() {
+	public byte[] getHandshakePublicKey() {
 		return handshakePublicKey;
 	}
 
@@ -74,7 +65,7 @@ public class Identity {
 	 * Returns the private key used for handshaking, or null if no key exists.
 	 */
 	@Nullable
-	public PrivateKey getHandshakePrivateKey() {
+	public byte[] getHandshakePrivateKey() {
 		return handshakePrivateKey;
 	}
 
@@ -85,4 +76,21 @@ public class Identity {
 	public long getTimeCreated() {
 		return created;
 	}
+
+	@Override
+	public int hashCode() {
+		return localAuthor.getId().hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (o instanceof Identity) {
+			Identity i = (Identity) o;
+			return created == i.created &&
+					localAuthor.equals(i.localAuthor) &&
+					Arrays.equals(handshakePublicKey, i.handshakePublicKey) &&
+					Arrays.equals(handshakePrivateKey, i.handshakePrivateKey);
+		}
+		return false;
+	}
 }

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

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.api.identity;
 
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
@@ -42,6 +41,9 @@ public interface IdentityManager {
 	 * Returns the cached handshake keys or loads them from the database.
 	 * <p/>
 	 * Read-only.
+	 *
+	 * @return A two-element array containing the public key in the first
+	 * element and the private key in the second
 	 */
-	KeyPair getHandshakeKeys(Transaction txn) throws DbException;
+	byte[][] getHandshakeKeys(Transaction txn) throws DbException;
 }

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

@@ -1,13 +1,9 @@
 package org.briarproject.bramble.api.identity;
 
-import org.briarproject.bramble.api.crypto.PrivateKey;
-import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.concurrent.Immutable;
 
-import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
-
 /**
  * A pseudonym for the local user.
  */
@@ -15,20 +11,18 @@ import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNA
 @NotNullByDefault
 public class LocalAuthor extends Author {
 
-	private final PrivateKey privateKey;
+	private final byte[] privateKey;
 
 	public LocalAuthor(AuthorId id, int formatVersion, String name,
-			PublicKey publicKey, PrivateKey privateKey) {
+			byte[] publicKey, byte[] privateKey) {
 		super(id, formatVersion, name, publicKey);
-		if (!privateKey.getKeyType().equals(KEY_TYPE_SIGNATURE))
-			throw new IllegalArgumentException();
 		this.privateKey = privateKey;
 	}
 
 	/**
 	 * Returns the private key used to generate the pseudonym's signatures.
 	 */
-	public PrivateKey getPrivateKey() {
+	public byte[] getPrivateKey() {
 		return privateKey;
 	}
 }

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

@@ -1,15 +0,0 @@
-package org.briarproject.bramble.api.io;
-
-import java.io.InputStream;
-
-public interface TimeoutMonitor {
-
-	/**
-	 * Returns an {@link InputStream} that wraps the given stream and allows
-	 * read timeouts to be detected.
-	 *
-	 * @param timeoutMs The read timeout in milliseconds. Timeouts will be
-	 * detected eventually but are not guaranteed to be detected immediately.
-	 */
-	InputStream createTimeoutInputStream(InputStream in, long timeoutMs);
-}

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

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

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

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

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

@@ -0,0 +1,22 @@
+package org.briarproject.bramble.api.plugin;
+
+/**
+ * Calculates polling intervals for transport plugins that use backoff.
+ */
+public interface Backoff {
+
+	/**
+	 * Returns the current polling interval.
+	 */
+	int getPollingInterval();
+
+	/**
+	 * Increments the backoff counter.
+	 */
+	void increment();
+
+	/**
+	 * Resets the backoff counter.
+	 */
+	void reset();
+}

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

@@ -0,0 +1,7 @@
+package org.briarproject.bramble.api.plugin;
+
+public interface BackoffFactory {
+
+	Backoff createBackoff(int minInterval, int maxInterval,
+			double base);
+}

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

@@ -6,10 +6,8 @@ public interface BluetoothConstants {
 
 	int UUID_BYTES = 16;
 
-	// Transport properties
 	String PROP_ADDRESS = "address";
 	String PROP_UUID = "uuid";
 
-	// Default value for PREF_PLUGIN_ENABLE
+	String PREF_BT_ENABLE = "enable";
-	boolean DEFAULT_PREF_PLUGIN_ENABLE = false;
 }

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

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

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

@@ -0,0 +1,17 @@
+package org.briarproject.bramble.api.plugin;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+public interface ConnectionManager {
+
+	void manageIncomingConnection(TransportId t, TransportConnectionReader r);
+
+	void manageIncomingConnection(TransportId t, DuplexTransportConnection d);
+
+	void manageOutgoingConnection(ContactId c, TransportId t,
+			TransportConnectionWriter w);
+
+	void manageOutgoingConnection(ContactId c, TransportId t,
+			DuplexTransportConnection d);
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.bramble.api.plugin;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+/**
+ * Keeps track of which contacts are currently connected by which transports.
+ */
+@NotNullByDefault
+public interface ConnectionRegistry {
+
+	void registerConnection(ContactId c, TransportId t, boolean incoming);
+
+	void unregisterConnection(ContactId c, TransportId t, boolean incoming);
+
+	Collection<ContactId> getConnectedContacts(TransportId t);
+
+	boolean isConnected(ContactId c, TransportId t);
+
+	boolean isConnected(ContactId c);
+}

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

@@ -4,15 +4,10 @@ public interface LanTcpConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.lan");
 
-	// Transport properties (shared with contacts)
+	// a transport property (shared with contacts)
 	String PROP_IP_PORTS = "ipPorts";
-	String PROP_PORT = "port";
-	String PROP_IPV6 = "ipv6";
 
-	// Local settings (not shared with contacts)
+	// a local setting
 	String PREF_LAN_IP_PORTS = "ipPorts";
-	String PREF_IPV6 = "ipv6";
 
-	// Default value for PREF_PLUGIN_ENABLE
-	boolean DEFAULT_PREF_PLUGIN_ENABLE = true;
 }

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

@@ -1,57 +1,14 @@
 package org.briarproject.bramble.api.plugin;
 
-import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.settings.SettingsManager;
 
-import java.util.Collection;
+import java.util.Map;
 
 @NotNullByDefault
 public interface Plugin {
 
-	enum State {
-
-		/**
-		 * The plugin has not finished starting or has been stopped.
-		 */
-		STARTING_STOPPING,
-
-		/**
-		 * The plugin is disabled by settings. Use {@link #getReasonsDisabled()}
-		 * to find out which settings are responsible.
-		 */
-		DISABLED,
-
-		/**
-		 * The plugin is being enabled and can't yet make or receive
-		 * connections.
-		 */
-		ENABLING,
-
-		/**
-		 * The plugin is enabled and can make or receive connections.
-		 */
-		ACTIVE,
-
-		/**
-		 * The plugin is enabled but can't make or receive connections
-		 */
-		INACTIVE
-	}
-
-	/**
-	 * The string for the boolean preference
-	 * to use with the {@link SettingsManager} to enable or disable the plugin.
-	 */
-	String PREF_PLUGIN_ENABLE = "enable";
-
-	/**
-	 * Reason flag returned by {@link #getReasonsDisabled()} to indicate that
-	 * the plugin has been disabled by the user.
-	 */
-	int REASON_USER = 1;
-
 	/**
 	 * Returns the plugin's transport identifier.
 	 */
@@ -78,18 +35,9 @@ public interface Plugin {
 	void stop() throws PluginException;
 
 	/**
-	 * Returns the current state of the plugin.
+	 * Returns true if the plugin is running.
 	 */
-	State getState();
+	boolean isRunning();
-
-	/**
-	 * Returns a set of flags indicating why the plugin is
-	 * {@link State#DISABLED disabled}, or 0 if the plugin is not disabled.
-	 * <p>
-	 * The flags used are plugin-specific, except the generic flag
-	 * {@link #REASON_USER}, which may be used by any plugin.
-	 */
-	int getReasonsDisabled();
 
 	/**
 	 * Returns true if the plugin should be polled periodically to attempt to
@@ -103,9 +51,8 @@ public interface Plugin {
 	int getPollingInterval();
 
 	/**
-	 * Attempts to create connections using the given transport properties,
+	 * Attempts to establish connections to the given contacts, passing any
-	 * passing any created connections to the corresponding handlers.
+	 * created connections to the callback.
 	 */
-	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
+	void poll(Map<ContactId, TransportProperties> contacts);
-			properties);
 }

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

@@ -1,10 +1,6 @@
 package org.briarproject.bramble.api.plugin;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
-import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
-import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
 
@@ -13,7 +9,7 @@ import org.briarproject.bramble.api.settings.Settings;
  * the application.
  */
 @NotNullByDefault
-public interface PluginCallback extends ConnectionHandler {
+public interface PluginCallback {
 
 	/**
 	 * Returns the plugin's settings
@@ -36,17 +32,12 @@ public interface PluginCallback extends ConnectionHandler {
 	void mergeLocalProperties(TransportProperties p);
 
 	/**
-	 * Informs the callback of the plugin's current state.
+	 * Signals that the transport is enabled.
-	 * <p>
-	 * If the current state is different from the previous state, the callback
-	 * will broadcast a {@link TransportStateEvent}. If the current state is
-	 * {@link State#ACTIVE} and the previous state was not
-	 * {@link State#ACTIVE}, the callback will broadcast a
-	 * {@link TransportActiveEvent}. If the current state is not
-	 * {@link State#ACTIVE} and the previous state was {@link State#ACTIVE},
-	 * the callback will broadcast a {@link TransportInactiveEvent}.
-	 * <p>
-	 * This method can safely be called while holding a lock.
 	 */
-	void pluginStateChanged(State state);
+	void transportEnabled();
+
+	/**
+	 * Signals that the transport is disabled.
+	 */
+	void transportDisabled();
 }

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

@@ -5,8 +5,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 
 import java.util.Collection;
-import java.util.List;
-import java.util.Map;
 
 @NotNullByDefault
 public interface PluginConfig {
@@ -16,11 +14,4 @@ public interface PluginConfig {
 	Collection<SimplexPluginFactory> getSimplexFactories();
 
 	boolean shouldPoll();
-
-	/**
-	 * Returns a map representing transport preferences. For each entry in the
-	 * map, connections via the transports identified by the value are
-	 * preferred to connections via the transport identified by the key.
-	 */
-	Map<TransportId, List<TransportId>> getTransportPreferences();
 }

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

@@ -36,22 +36,4 @@ public interface PluginManager {
 	 * Returns any duplex plugins that support key agreement.
 	 */
 	Collection<DuplexPlugin> getKeyAgreementPlugins();
-
-	/**
-	 * Returns any duplex plugins that support rendezvous.
-	 */
-	Collection<DuplexPlugin> getRendezvousPlugins();
-
-	/**
-	 * Enables or disables the plugin
-	 * identified by the given {@link TransportId}.
-	 * <p>
-	 * Note that this applies the change asynchronously
-	 * and there are no order guarantees.
-	 * <p>
-	 * If no plugin with the given {@link TransportId} is registered,
-	 * this is a no-op.
-	 */
-	void setPluginEnabled(TransportId t, boolean enabled);
-
 }

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

@@ -1,12 +1,9 @@
 package org.briarproject.bramble.api.plugin;
 
-import static java.util.concurrent.TimeUnit.DAYS;
-
 public interface TorConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.tor");
 
-	// Transport properties
 	String PROP_ONION_V2 = "onion";
 	String PROP_ONION_V3 = "onion3";
 
@@ -16,45 +13,14 @@ public interface TorConstants {
 	int CONNECT_TO_PROXY_TIMEOUT = 5000; // Milliseconds
 	int EXTRA_SOCKET_TIMEOUT = 30000; // Milliseconds
 
-	// Local settings (not shared with contacts)
 	String PREF_TOR_NETWORK = "network2";
 	String PREF_TOR_PORT = "port";
 	String PREF_TOR_MOBILE = "useMobileData";
 	String PREF_TOR_ONLY_WHEN_CHARGING = "onlyWhenCharging";
-	String HS_PRIVATE_KEY_V2 = "onionPrivKey";
-	String HS_PRIVATE_KEY_V3 = "onionPrivKey3";
-	String HS_V3_CREATED = "onionPrivKey3Created";
 
-	/**
-	 * How long to publish a v3 hidden service before retiring the v2 service.
-	 */
-	long V3_MIGRATION_PERIOD_MS = DAYS.toMillis(180);
-
-	// Values for PREF_TOR_NETWORK
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;
 	int PREF_TOR_NETWORK_WITHOUT_BRIDGES = 1;
 	int PREF_TOR_NETWORK_WITH_BRIDGES = 2;
-	// TODO: Remove when settings migration code is removed
 	int PREF_TOR_NETWORK_NEVER = 3;
 
-	// Default values for local settings
-	boolean DEFAULT_PREF_PLUGIN_ENABLE = true;
-	int DEFAULT_PREF_TOR_NETWORK = PREF_TOR_NETWORK_AUTOMATIC;
-	boolean DEFAULT_PREF_TOR_MOBILE = true;
-	boolean DEFAULT_PREF_TOR_ONLY_WHEN_CHARGING = false;
-
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_BATTERY = 2;
-
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_MOBILE_DATA = 4;
-
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_COUNTRY_BLOCKED = 8;
 }

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

@@ -4,7 +4,4 @@ public interface WanTcpConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.wan");
 
-	// Default value for PREF_PLUGIN_ENABLE
-	boolean DEFAULT_PREF_PLUGIN_ENABLE = false;
 }
-

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

@@ -4,7 +4,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
-import org.briarproject.bramble.api.properties.TransportProperties;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -15,8 +14,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 public abstract class AbstractDuplexTransportConnection
 		implements DuplexTransportConnection {
 
-	protected final TransportProperties remote = new TransportProperties();
-
 	private final Plugin plugin;
 	private final Reader reader;
 	private final Writer writer;
@@ -47,11 +44,6 @@ public abstract class AbstractDuplexTransportConnection
 		return writer;
 	}
 
-	@Override
-	public TransportProperties getRemoteProperties() {
-		return remote;
-	}
-
 	private class Reader implements TransportConnectionReader {
 
 		@Override

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

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

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

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

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

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

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

@@ -3,7 +3,6 @@ package org.briarproject.bramble.api.plugin.duplex;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
-import org.briarproject.bramble.api.properties.TransportProperties;
 
 /**
  * An interface for reading and writing data over a duplex transport. The
@@ -24,10 +23,4 @@ public interface DuplexTransportConnection {
 	 * for writing to the connection.
 	 */
 	TransportConnectionWriter getWriter();
-
-	/**
-	 * Returns a possibly empty set of {@link TransportProperties} describing
-	 * the remote peer.
-	 */
-	TransportProperties getRemoteProperties();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/ConnectionClosedEvent.java

@@ -13,14 +13,13 @@ public class ConnectionClosedEvent extends Event {
 
 	private final ContactId contactId;
 	private final TransportId transportId;
-	private final boolean incoming, exception;
+	private final boolean incoming;
 
 	public ConnectionClosedEvent(ContactId contactId, TransportId transportId,
-			boolean incoming, boolean exception) {
+			boolean incoming) {
 		this.contactId = contactId;
 		this.transportId = transportId;
 		this.incoming = incoming;
-		this.exception = exception;
 	}
 
 	public ContactId getContactId() {
@@ -34,8 +33,4 @@ public class ConnectionClosedEvent extends Event {
 	public boolean isIncoming() {
 		return incoming;
 	}
-
-	public boolean isException() {
-		return exception;
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/TransportDisabledEvent.java

@@ -2,22 +2,20 @@ package org.briarproject.bramble.api.plugin.event;
 
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a plugin enters the {@link State#ACTIVE}
+ * An event that is broadcast when a transport is disabled.
- * state.
  */
 @Immutable
 @NotNullByDefault
-public class TransportActiveEvent extends Event {
+public class TransportDisabledEvent extends Event {
 
 	private final TransportId transportId;
 
-	public TransportActiveEvent(TransportId transportId) {
+	public TransportDisabledEvent(TransportId transportId) {
 		this.transportId = transportId;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/TransportEnabledEvent.java

@@ -2,22 +2,20 @@ package org.briarproject.bramble.api.plugin.event;
 
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a plugin leaves the {@link State#ACTIVE}
+ * An event that is broadcast when a transport is enabled.
- * state.
  */
 @Immutable
 @NotNullByDefault
-public class TransportInactiveEvent extends Event {
+public class TransportEnabledEvent extends Event {
 
 	private final TransportId transportId;
 
-	public TransportInactiveEvent(TransportId transportId) {
+	public TransportEnabledEvent(TransportId transportId) {
 		this.transportId = transportId;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/TransportStateEvent.java

@@ -1,32 +0,0 @@
-package org.briarproject.bramble.api.plugin.event;
-
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
-import org.briarproject.bramble.api.plugin.TransportId;
-
-import javax.annotation.concurrent.Immutable;
-
-/**
- * An event that is broadcast when the {@link State state} of a plugin changes.
- */
-@Immutable
-@NotNullByDefault
-public class TransportStateEvent extends Event {
-
-	private final TransportId transportId;
-	private final State state;
-
-	public TransportStateEvent(TransportId transportId, State state) {
-		this.transportId = transportId;
-		this.state = state;
-	}
-
-	public TransportId getTransportId() {
-		return transportId;
-	}
-
-	public State getState() {
-		return state;
-	}
-}

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

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

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

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

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

@@ -11,28 +11,4 @@ public interface TransportPropertyConstants {
 	 * The maximum length of a property's key or value in UTF-8 bytes.
 	 */
 	int MAX_PROPERTY_LENGTH = 100;
-
-	/**
-	 * Message metadata key for the transport ID of a local or remote update,
-	 * as a BDF string.
-	 */
-	String MSG_KEY_TRANSPORT_ID = "transportId";
-
-	/**
-	 * Message metadata key for the version number of a local or remote update,
-	 * as a BDF long.
-	 */
-	String MSG_KEY_VERSION = "version";
-
-	/**
-	 * Message metadata key for whether an update is local or remote, as a BDF
-	 * boolean.
-	 */
-	String MSG_KEY_LOCAL = "local";
-
-	/**
-	 * Group metadata key for any discovered transport properties of the
-	 * contact, as a BDF dictionary.
-	 */
-	String GROUP_KEY_DISCOVERED = "discovered";
 }

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

@@ -34,14 +34,6 @@ public interface TransportPropertyManager {
 	void addRemoteProperties(Transaction txn, ContactId c,
 			Map<TransportId, TransportProperties> props) throws DbException;
 
-	/**
-	 * Stores the given properties discovered from an incoming transport
-	 * connection. They will be overridden by any properties received while
-	 * adding the contact or synced from the contact.
-	 */
-	void addRemotePropertiesFromConnection(ContactId c, TransportId t,
-			TransportProperties props) throws DbException;
-
 	/**
 	 * Returns the local transport properties for all transports.
 	 */

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

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