Write any records in the queue before ending session.

This maintains compatibility with older peers that don't know about
priorities or transport preferences and will try to replace any
connections we close.

.gitlab-ci.yml

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

.idea/codeStyles/Project.xml

@@ -1,16 +1,10 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
-    <option name="RIGHT_MARGIN" value="100" />
     <AndroidXmlCodeStyleSettings>
-      <option name="USE_CUSTOM_SETTINGS" value="true" />
+      <option name="ARRANGEMENT_SETTINGS_MIGRATED_TO_191" 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" />
@@ -39,31 +33,6 @@
     <JetCodeStyleSettings>
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
-    <Objective-C-extensions>
-      <file>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
-      </file>
-      <class>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
-      </class>
-      <extensions>
-        <pair source="cpp" header="h" fileNamingConvention="NONE" />
-        <pair source="c" header="h" fileNamingConvention="NONE" />
-      </extensions>
-    </Objective-C-extensions>
     <XML>
       <option name="XML_LEGACY_SETTINGS_IMPORTED" value="true" />
     </XML>
@@ -102,7 +71,6 @@
       </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" />
@@ -115,7 +83,8 @@
               <match>
                 <AND>
                   <NAME>xmlns:android</NAME>
-                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
+                  <XML_ATTRIBUTE />
+                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
             </rule>
@@ -125,7 +94,8 @@
               <match>
                 <AND>
                   <NAME>xmlns:.*</NAME>
-                  <XML_NAMESPACE>Namespace:</XML_NAMESPACE>
+                  <XML_ATTRIBUTE />
+                  <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
               <order>BY_NAME</order>
@@ -136,6 +106,7 @@
               <match>
                 <AND>
                   <NAME>.*:id</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
@@ -146,6 +117,7 @@
               <match>
                 <AND>
                   <NAME>.*:name</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
@@ -156,6 +128,7 @@
               <match>
                 <AND>
                   <NAME>name</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -166,6 +139,7 @@
               <match>
                 <AND>
                   <NAME>style</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -176,6 +150,7 @@
               <match>
                 <AND>
                   <NAME>.*</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>^$</XML_NAMESPACE>
                 </AND>
               </match>
@@ -186,64 +161,12 @@
             <rule>
               <match>
                 <AND>
-                  <NAME>.*:layout_width</NAME>
+                  <NAME>.*</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>http://schemas.android.com/apk/res/android</XML_NAMESPACE>
                 </AND>
               </match>
-            </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>
+              <order>ANDROID_ATTRIBUTE_ORDER</order>
             </rule>
           </section>
           <section>
@@ -251,6 +174,7 @@
               <match>
                 <AND>
                   <NAME>.*</NAME>
+                  <XML_ATTRIBUTE />
                   <XML_NAMESPACE>.*</XML_NAMESPACE>
                 </AND>
               </match>

.idea/runConfigurations/All_in_briar_headless.xml

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

.idea/runConfigurations/All_tests.xml

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

.idea/runConfigurations/All_tests_in_briar_headless.xml

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

bramble-android/build.gradle

@@ -5,23 +5,31 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion 28
-	buildToolsVersion '28.0.3'
+	compileSdkVersion 29
+	buildToolsVersion '29.0.2'
 
 	defaultConfig {
-		minSdkVersion 14
-		targetSdkVersion 26
-		versionCode 10106
-		versionName "1.1.6"
+		minSdkVersion 16
+		targetSdkVersion 28
+		versionCode 10207
+		versionName "1.2.7"
 		consumerProguardFiles 'proguard-rules.txt'
 
-		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+		testInstrumentationRunner "androidx.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 {
@@ -30,10 +38,10 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.9@zip'
+	tor 'org.briarproject:tor-android:0.3.5.10@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
@@ -59,6 +67,8 @@ 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

@@ -2,10 +2,23 @@ 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

@@ -3,6 +3,8 @@ package org.briarproject.bramble;
 import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
 import org.briarproject.bramble.plugin.tor.CircumventionModule;
+import org.briarproject.bramble.reporting.ReportingModule;
+import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.system.AndroidSystemModule;
 
 import dagger.Module;
@@ -11,12 +13,9 @@ 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

@@ -9,17 +9,22 @@ 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 {
@@ -27,7 +32,11 @@ 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;
@@ -41,42 +50,30 @@ class AndroidAccountManager extends AccountManagerImpl
 		appContext = app.getApplicationContext();
 	}
 
-	// Locking: stateChangeLock
 	@Override
-	@Nullable
-	protected String loadEncryptedDatabaseKey() {
-		String key = getDatabaseKeyFromPreferences();
-		if (key == null) key = super.loadEncryptedDatabaseKey();
-		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");
+	public boolean accountExists() {
+		boolean exists = super.accountExists();
+		if (!exists && LOG.isLoggable(INFO)) {
+			LOG.info("Account does not exist. Contents of account directory:");
+			logFileOrDir(LOG, INFO, getDataDir());
 		}
+		return exists;
 	}
 
 	@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());
+			}
 		}
 	}
 
@@ -85,30 +82,28 @@ class AndroidAccountManager extends AccountManagerImpl
 		return PreferenceManager.getDefaultSharedPreferences(appContext);
 	}
 
-	// Locking: stateChangeLock
+	@GuardedBy("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 lib and shared_prefs directories
+		// Delete files, except protected directories
 		Set<File> files = new HashSet<>();
-		File dataDir = new File(appContext.getApplicationInfo().dataDir);
+		File dataDir = getDataDir();
 		@Nullable
 		File[] fileArray = dataDir.listFiles();
 		if (fileArray == null) {
 			LOG.warning("Could not list files in app data dir");
 		} else {
 			for (File file : fileArray) {
-				String name = file.getName();
-				if (!name.equals("lib") && !name.equals("shared_prefs")) {
+				if (!PROTECTED_DIR_NAMES.contains(file.getName())) {
 					files.add(file);
 				}
 			}
 		}
 		files.add(appContext.getFilesDir());
-		files.add(appContext.getCacheDir());
 		addIfNotNull(files, appContext.getExternalCacheDir());
 		if (SDK_INT >= 19) {
 			for (File file : appContext.getExternalCacheDirs()) {
@@ -120,12 +115,20 @@ 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) {
-			IoUtils.deleteFileOrDir(file);
+			if (LOG.isLoggable(INFO)) {
+				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())
-			LOG.warning("Could not recreate cache dir");
+	}
+
+	private File getDataDir() {
+		return new File(appContext.getApplicationInfo().dataDir);
 	}
 
 	private void addIfNotNull(Set<File> files, @Nullable File file) {

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

@@ -32,6 +32,7 @@ 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;
@@ -76,9 +77,9 @@ 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
@@ -136,7 +137,8 @@ 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 +9,12 @@ 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.Backoff;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
@@ -24,7 +25,6 @@ import java.io.IOException;
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.BlockingQueue;
@@ -47,10 +47,14 @@ 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
@@ -58,7 +62,7 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	private static final Logger LOG =
-			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
+			getLogger(AndroidBluetoothPlugin.class.getName());
 
 	private static final int MAX_DISCOVERY_MS = 10_000;
 
@@ -73,11 +77,12 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private volatile BluetoothAdapter adapter = null;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			Executor ioExecutor, AndroidExecutor androidExecutor,
-			Context appContext, SecureRandom secureRandom, Clock clock,
-			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
-		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
-				maxLatency);
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
+			SecureRandom secureRandom, AndroidExecutor androidExecutor,
+			Context appContext, Clock clock, Backoff backoff,
+			PluginCallback callback, int maxLatency, int maxIdleTime) {
+		super(connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
+				backoff, callback, maxLatency, maxIdleTime);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.clock = clock;
@@ -169,9 +174,10 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return wrapSocket(ss.accept());
 	}
 
-	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-		return new AndroidBluetoothTransportConnection(this,
-				connectionLimiter, s);
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s)
+			throws IOException {
+		return new AndroidBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, s);
 	}
 
 	@Override
@@ -239,11 +245,15 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 						break;
 					} else if (ACTION_FOUND.equals(action)) {
 						BluetoothDevice d = i.getParcelableExtra(EXTRA_DEVICE);
-						String address = d.getAddress();
-						if (LOG.isLoggable(INFO))
-							LOG.info("Discovered " + scrubMacAddress(address));
-						if (!addresses.contains(address))
-							addresses.add(address);
+						// Ignore Bluetooth LE devices
+						if (SDK_INT < 18 || d.getType() != DEVICE_TYPE_LE) {
+							String address = d.getAddress();
+							if (LOG.isLoggable(INFO))
+								LOG.info("Discovered " +
+										scrubMacAddress(address));
+							if (!addresses.contains(address))
+								addresses.add(address);
+						}
 					}
 					now = clock.currentTimeMillis();
 				}
@@ -259,7 +269,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			appContext.unregisterReceiver(receiver);
 		}
 		// Shuffle the addresses so we don't always try the same one first
-		Collections.shuffle(addresses);
+		shuffle(addresses);
 		return addresses;
 	}
 

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

@@ -3,12 +3,13 @@ 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.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
@@ -25,6 +26,7 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	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
 	private static final double BACKOFF_BASE = 1.2;
@@ -35,18 +37,20 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
 	private final Clock clock;
+	private final TimeoutMonitor timeoutMonitor;
 	private final BackoffFactory backoffFactory;
 
 	public AndroidBluetoothPluginFactory(Executor ioExecutor,
 			AndroidExecutor androidExecutor, Context appContext,
 			SecureRandom secureRandom, EventBus eventBus, Clock clock,
-			BackoffFactory backoffFactory) {
+			TimeoutMonitor timeoutMonitor, BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
 		this.clock = clock;
+		this.timeoutMonitor = timeoutMonitor;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -61,14 +65,15 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
 				new BluetoothConnectionLimiterImpl();
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
-				connectionLimiter, ioExecutor, androidExecutor, appContext,
-				secureRandom, clock, backoff, callback, MAX_LATENCY);
+				connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
+				androidExecutor, appContext, clock, backoff,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
 
+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;
@@ -10,24 +11,33 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.util.AndroidUtils.isValidBluetoothAddress;
+
 @NotNullByDefault
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
-	private final BluetoothConnectionLimiter connectionManager;
+	private final BluetoothConnectionLimiter connectionLimiter;
 	private final BluetoothSocket socket;
+	private final InputStream in;
 
 	AndroidBluetoothTransportConnection(Plugin plugin,
-			BluetoothConnectionLimiter connectionManager,
-			BluetoothSocket socket) {
+			BluetoothConnectionLimiter connectionLimiter,
+			TimeoutMonitor timeoutMonitor, BluetoothSocket socket)
+			throws IOException {
 		super(plugin);
-		this.connectionManager = connectionManager;
+		this.connectionLimiter = connectionLimiter;
 		this.socket = socket;
+		in = timeoutMonitor.createTimeoutInputStream(
+				socket.getInputStream(), plugin.getMaxIdleTime() * 2);
+		String address = socket.getRemoteDevice().getAddress();
+		if (isValidBluetoothAddress(address)) remote.put(PROP_ADDRESS, address);
 	}
 
 	@Override
-	protected InputStream getInputStream() throws IOException {
-		return socket.getInputStream();
+	protected InputStream getInputStream() {
+		return in;
 	}
 
 	@Override
@@ -40,7 +50,7 @@ class AndroidBluetoothTransportConnection
 		try {
 			socket.close();
 		} finally {
-			connectionManager.connectionClosed(this);
+			connectionLimiter.connectionClosed(this);
 		}
 	}
 }

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

@@ -13,13 +13,13 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.Socket;
 import java.net.UnknownHostException;
-import java.util.Collection;
+import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -32,25 +32,13 @@ import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
+import static java.util.logging.Logger.getLogger;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
-	private static final byte[] WIFI_AP_ADDRESS_BYTES =
-			{(byte) 192, (byte) 168, 43, 1};
-	private static final InetAddress WIFI_AP_ADDRESS;
-
 	private static final Logger LOG =
-			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
-
-	static {
-		try {
-			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
-		} catch (UnknownHostException e) {
-			// Should only be thrown if the address has an illegal length
-			throw new AssertionError(e);
-		}
-	}
+			getLogger(AndroidLanTcpPlugin.class.getName());
 
 	private final Executor connectionStatusExecutor;
 	private final ConnectivityManager connectivityManager;
@@ -60,9 +48,10 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	private volatile SocketFactory socketFactory;
 
 	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
-			Backoff backoff, DuplexPluginCallback callback, int maxLatency,
-			int maxIdleTime) {
-		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+			Backoff backoff, PluginCallback callback, int maxLatency,
+			int maxIdleTime, int connectionTimeout) {
+		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);
@@ -78,6 +67,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
+		initialisePortProperty();
 		running = true;
 		updateConnectionStatus();
 	}
@@ -94,16 +84,19 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	}
 
 	@Override
-	protected Collection<InetAddress> getLocalIpAddresses() {
+	protected List<InetAddress> getUsableLocalInetAddresses() {
 		// If the device doesn't have wifi, don't open any sockets
 		if (wifiManager == null) return emptyList();
-		// If we're connected to a wifi network, use that network
+		// 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 singletonList(intToInetAddress(info.getIpAddress()));
+		}
 		// If we're running an access point, return its address
-		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
-			return singletonList(WIFI_AP_ADDRESS);
+		for (InetAddress addr : getLocalInetAddresses()) {
+			if (addr.equals(WIFI_AP_ADDRESS)) return singletonList(addr);
+			if (addr.equals(WIFI_DIRECT_AP_ADDRESS)) return singletonList(addr);
+		}
 		// No suitable addresses
 		return emptyList();
 	}
@@ -143,8 +136,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	private void updateConnectionStatus() {
 		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
-			Collection<InetAddress> addrs = getLocalIpAddresses();
-			if (addrs.contains(WIFI_AP_ADDRESS)) {
+			List<InetAddress> addrs = getUsableLocalInetAddresses();
+			if (addrs.contains(WIFI_AP_ADDRESS)
+					|| addrs.contains(WIFI_DIRECT_AP_ADDRESS)) {
 				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

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

@@ -6,9 +6,9 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
@@ -21,10 +21,11 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 @NotNullByDefault
 public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
-	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
+	private static final int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int CONNECTION_TIMEOUT = 3_000; // 3 seconds
+	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
@@ -51,11 +52,12 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidLanTcpPlugin plugin = new AndroidLanTcpPlugin(ioExecutor,
-				appContext, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME);
+				appContext, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME,
+				CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

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

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

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.plugin.tor;
 
 import android.content.Context;
-import android.os.Build;
 
 import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
@@ -9,10 +8,10 @@ import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
@@ -84,14 +83,20 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+	public DuplexPlugin createPlugin(PluginCallback callback) {
 
 		// Check that we have a Tor binary for this architecture
 		String architecture = null;
 		for (String abi : AndroidUtils.getSupportedArchitectures()) {
-			if (abi.startsWith("x86")) {
+			if (abi.startsWith("x86_64")) {
+				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;
@@ -101,15 +106,17 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			LOG.info("Tor is not supported on this architecture");
 			return null;
 		}
-		// Use position-independent executable for SDK >= 16
-		if (Build.VERSION.SDK_INT >= 16) architecture += "_pie";
+		// Use position-independent executable
+		architecture += "_pie";
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
 		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor, scheduler,
 				appContext, networkManager, locationUtils, torSocketFactory,
 				clock, resourceProvider, circumventionProvider, batteryManager,
-				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
+				backoff, torRendezvousCrypto, callback, architecture,
+				MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -23,6 +23,7 @@ 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
@@ -74,8 +75,7 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		// Silence strict mode
 		StrictMode.ThreadPolicy tp = StrictMode.allowThreadDiskWrites();
 		super.writeSeed();
-		if (Build.VERSION.SDK_INT >= 16 && Build.VERSION.SDK_INT <= 18)
-			applyOpenSslFix();
+		if (SDK_INT <= 18) applyOpenSslFix();
 		StrictMode.setThreadPolicy(tp);
 	}
 

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

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

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

@@ -6,15 +6,25 @@ import android.content.Context;
 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
@@ -22,11 +32,10 @@ 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(Arrays.asList(Build.SUPPORTED_ABIS));
+			abis.addAll(asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);
 			if (Build.CPU_ABI2 != null) abis.add(Build.CPU_ABI2);
@@ -36,25 +45,76 @@ 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)) return address;
+		if (isValidBluetoothAddress(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)) return address;
+		if (isValidBluetoothAddress(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 "";
+		return new Pair<>("", "");
 	}
 
-	private static boolean isValidBluetoothAddress(String address) {
+	public static boolean isValidBluetoothAddress(@Nullable 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"};
+	}
 }

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

@@ -16,13 +16,10 @@ 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 {
 
@@ -40,11 +37,8 @@ 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;
@@ -75,33 +69,12 @@ 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 'lib' and 'shared_prefs' should be spared
+		// Directories 'code_cache', '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");
@@ -128,7 +101,7 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 			will(returnValue(editor));
 			oneOf(editor).commit();
 			will(returnValue(true));
-			oneOf(app).getApplicationInfo();
+			allowing(app).getApplicationInfo();
 			will(returnValue(applicationInfo));
 			oneOf(app).getFilesDir();
 			will(returnValue(filesDir));
@@ -140,6 +113,8 @@ 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());
@@ -155,6 +130,8 @@ 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

@@ -1,45 +1,47 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:26.3.2:protos-26.3.2.jar:50238fb4298b297217b184b9cd93c14f83536fcee829eb0ca850bdb5b53251f0',
-        'com.android.tools.analytics-library:shared:26.3.2:shared-26.3.2.jar:ddd80dcf21905018b7c0583ba72b7282f446084d4952422609a09fbf8237ef71',
-        'com.android.tools.analytics-library:tracker:26.3.2:tracker-26.3.2.jar:28c575d2d1af003e96d7b375a668ee10b2673a2dd0f6438750aa8c3b42e7d0ad',
-        'com.android.tools.build:apksig:3.3.2:apksig-3.3.2.jar:84c4aaa20127c6c1fe6bdd334b3f5df71f54ad080be9029c8a10f43b6a908acd',
-        'com.android.tools.build:apkzlib:3.3.2:apkzlib-3.3.2.jar:d34e523278e5dff565eba3ef3c089d515b2b5cc7b47dc77e2f3465e5e47176ac',
-        'com.android.tools.build:builder-model:3.3.2:builder-model-3.3.2.jar:055e3db0ecee9e06b9f024034999a29cd92cb1885207b37542126bd8bcc57f46',
-        'com.android.tools.build:builder-test-api:3.3.2:builder-test-api-3.3.2.jar:0b2e4cd7615bbcad14a3c91fe45ae26693508d06e40ba06c5968b8bc24416618',
-        'com.android.tools.build:builder:3.3.2:builder-3.3.2.jar:65649704da7aef0487235fd326f0f2e99ed5cf958e80f204496e6e08a42bd9f5',
-        'com.android.tools.build:gradle-api:3.3.2:gradle-api-3.3.2.jar:3cbd47e41bb70330dd72ec2c9fe51e6173554b484a03829b5a2de9e00841e040',
-        'com.android.tools.build:manifest-merger:26.3.2:manifest-merger-26.3.2.jar:05c4a6d8b02fb9f08744876477d0a68547c03a8a9069b1f086684fa04af97c33',
-        'com.android.tools.ddms:ddmlib:26.3.2:ddmlib-26.3.2.jar:d248da8a563d6e46d2c7ebbf371a4877e00510f4ca763c0bb272d5a281bf8b85',
-        'com.android.tools.external.com-intellij:intellij-core:26.3.2:intellij-core-26.3.2.jar:6c5ecc968230e9f4dcd0fef28885379feace1f0cd8130de6f61d649c86139bf3',
-        'com.android.tools.external.com-intellij:kotlin-compiler:26.3.2:kotlin-compiler-26.3.2.jar:1007d9b07ccb49cd8eaf30fda10ed4681d4714f2f9ab2ecda39b4e539cc51bbe',
-        'com.android.tools.external.org-jetbrains:uast:26.3.2:uast-26.3.2.jar:5d1833e562ea4f38a89708dfde695f0a162cbd39d003d3dde818c3fdc2b05317',
-        'com.android.tools.layoutlib:layoutlib-api:26.3.2:layoutlib-api-26.3.2.jar:d7e61e874ab95f5c350dd38b6a95b5c9dbe0083a02001884264cdb390cb255b8',
-        'com.android.tools.lint:lint-api:26.3.2:lint-api-26.3.2.jar:5867dfd7fb4a4e161a816a5d29d045f9b542d34594c00a1efec46fb4cd0e1033',
-        'com.android.tools.lint:lint-checks:26.3.2:lint-checks-26.3.2.jar:4b163b9c93790d2771e92ba8de58a0d9e0671ffcf2ccef3cf496efd442e27517',
-        'com.android.tools.lint:lint-gradle-api:26.3.2:lint-gradle-api-26.3.2.jar:54cb282e0c054f9bed3f51302ce08b003c8ab7961dfd5a4f6de26c23cc23062f',
-        'com.android.tools.lint:lint-gradle:26.3.2:lint-gradle-26.3.2.jar:bb139615f4ce97d42cc394b9389b49b76a6eb85be6785a5d272991543b519013',
-        'com.android.tools.lint:lint:26.3.2:lint-26.3.2.jar:ef7b369f8a56a92ccb0f4c1c357666b9339e4a711a9d84747d446441746cfe4e',
-        'com.android.tools:annotations:26.3.2:annotations-26.3.2.jar:5bcce8e98b6a2f5ccf13ebcefd8f734e0b35f8b19e456575665631442ce1f7a1',
-        'com.android.tools:common:26.3.2:common-26.3.2.jar:d9f8e7f0669e9a701568e3db6a87c89cf12d8fa6811c9991e969f950215ecfac',
-        'com.android.tools:dvlib:26.3.2:dvlib-26.3.2.jar:d84aad56161c7773579303d69714ded6897c64c6ddfd7d456e453231e4dfe811',
-        'com.android.tools:repository:26.3.2:repository-26.3.2.jar:da611eeb06e9ab8750d25b9e2901e10db8e5ec6304eb4c8b7103d39e0921ea40',
-        'com.android.tools:sdk-common:26.3.2:sdk-common-26.3.2.jar:82823a3bf25e64fac33a286490f0cf5ac50c2cdb3c540149b030896bb44bf96c',
-        'com.android.tools:sdklib:26.3.2:sdklib-26.3.2.jar:424d15492af67321900963238646d27495ab60de2a5b19e6a416963bc5d6932b',
-        'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
+        'com.android.tools.analytics-library:protos:26.5.1:protos-26.5.1.jar:8dde1130725461fe827f2a343d353f2b51e8870661fc860d7d5ebddb097ead4e',
+        'com.android.tools.analytics-library:shared:26.5.1:shared-26.5.1.jar:ccc2f3b00ec17b11401610ba68553544fc8fc517120e84439ac6eb86b875e18d',
+        'com.android.tools.analytics-library:tracker:26.5.1:tracker-26.5.1.jar:3a76984c0fe2e847ca7a8b35b4780ef0447a9d1666946cb8e60466318e0ab5ae',
+        'com.android.tools.build:aapt2-proto:0.4.0:aapt2-proto-0.4.0.jar:fac0435e08898f89eeeb9ca236bea707155ff816c12205ced285ad53604133ca',
+        'com.android.tools.build:apksig:3.5.1:apksig-3.5.1.jar:1fd33e7f009a2a0da766cfeec4211a09f548034b015c289a66d75dd8a9302f4a',
+        'com.android.tools.build:apkzlib:3.5.1:apkzlib-3.5.1.jar:9f330167cbe973b7db407692f74f4f6453b7ffa5f2048934b06280c2ceee60fa',
+        'com.android.tools.build:builder-model:3.5.1:builder-model-3.5.1.jar:39ea3c82b76b6e0c9f9fa88d93e0edc1dd4a0f1dfae0ef6fbf2d451da47e5450',
+        'com.android.tools.build:builder-test-api:3.5.1:builder-test-api-3.5.1.jar:a1b59305584cbcaa078fdc9cfb80871012755b822dd32e8da19add6f7bbcb762',
+        'com.android.tools.build:builder:3.5.1:builder-3.5.1.jar:e3a8d382434c5f60990730c4719fc814e85a898a33a1e96c1df8d627d3c6eea6',
+        'com.android.tools.build:gradle-api:3.5.1:gradle-api-3.5.1.jar:be9b41859bace11998f66b04ed944f87e413f3ad6da3c4665587699da125addc',
+        'com.android.tools.build:manifest-merger:26.5.1:manifest-merger-26.5.1.jar:dcad9ecb967251f4d750f55a4204a2b400e8fbfe5cb930a1d0d5dbe10ae8bdfc',
+        'com.android.tools.ddms:ddmlib:26.5.1:ddmlib-26.5.1.jar:b081aef2a4ed3f4d47cae4cdb128469735f25a114e026d37123bf9ffdec742a8',
+        '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:26.5.1:kotlin-compiler-26.5.1.jar:5aed762dd54875b77ae7018d97c05756ff0c5b9fd02ec595dd396ccd14cc22cb',
+        'com.android.tools.external.org-jetbrains:uast:26.5.1:uast-26.5.1.jar:4bc8653d6c0943f40fee963a149e36c6baa45683d2530968a13f5007e3c40740',
+        'com.android.tools.layoutlib:layoutlib-api:26.5.1:layoutlib-api-26.5.1.jar:88732f11396c427273e515d23042e35633f4fe4295528a99b866aa2adf0efd9c',
+        'com.android.tools.lint:lint-api:26.5.1:lint-api-26.5.1.jar:ec33fcd72bfaf70dd841e03fbfd93f109c2e575aec146067c606689c3972f0de',
+        'com.android.tools.lint:lint-checks:26.5.1:lint-checks-26.5.1.jar:a1b9607d484aaae7a71dcecdc76f8003d8239af226c776894a2cf63f9e6c60d7',
+        'com.android.tools.lint:lint-gradle-api:26.5.1:lint-gradle-api-26.5.1.jar:82453fd98a8394cc84ed995c04d2cd744abd1d6589403427ba7eef53115406f3',
+        'com.android.tools.lint:lint-gradle:26.5.1:lint-gradle-26.5.1.jar:59465b56cf7db77c656d5f8195d721c3d48b6bdd0502d774de335bfe4baff00b',
+        'com.android.tools.lint:lint:26.5.1:lint-26.5.1.jar:336e4b04ec6f8b0f25879131b7a7862d77df83a1879ee5b71be26128755f8e2e',
+        'com.android.tools:annotations:26.5.1:annotations-26.5.1.jar:2c43c82f8c59d8f7a61e3239e1a2dc9f69dc342ec09af9b7c9f69b25337c0b6e',
+        'com.android.tools:common:26.5.1:common-26.5.1.jar:eccfa54486ed54c4e3123cc42195d023bd0dd21bcd2f0e4868e8c6fc70f8ef6b',
+        'com.android.tools:dvlib:26.5.1:dvlib-26.5.1.jar:46f93ad498b4756e7d867d2fe38c38890a80e7407a4ae459e4a8c8d5c5aeacfe',
+        'com.android.tools:repository:26.5.1:repository-26.5.1.jar:2b3ee791aa4c3e8ce60498c161a27ca7228816fc630eed4d9f25f2f36a106dce',
+        'com.android.tools:sdk-common:26.5.1:sdk-common-26.5.1.jar:365f749676c3574676fd465177c8a492f340816db2b520d6ed114d3b6e77bea7',
+        'com.android.tools:sdklib:26.5.1:sdklib-26.5.1.jar:007da104afb27c8c682a1628023fe9ec438249c8d15ef0fd6624c5bb8e23b696',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.code.gson:gson:2.8.0:gson-2.8.0.jar:c6221763bd79c4f1c3dc7f750b5f29a0bb38b367b81314c4f71896e340c40825',
-        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
-        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
-        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
-        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
-        'com.google.errorprone:error_prone_annotations:2.1.3:error_prone_annotations-2.1.3.jar:03d0329547c13da9e17c634d1049ea2ead093925e290567e1a364fd6b1fc7ff8',
+        'com.google.code.gson:gson:2.8.5:gson-2.8.5.jar:233a0149fc365c9f6edbd683cfe266b19bdc773be98eabdaf6b3c924b48e7d81',
+        'com.google.dagger:dagger-compiler:2.24:dagger-compiler-2.24.jar:3c5afb955fb188da485cb2c048eff37dce0e1530b9780a0f2f7187d16d1ccc1f',
+        'com.google.dagger:dagger-producers:2.24:dagger-producers-2.24.jar:f10f45b95191954d5d6b043fca9e62fb621d21bf70634b8f8476c7988b504c3a',
+        'com.google.dagger:dagger-spi:2.24:dagger-spi-2.24.jar:c038445d14dbcb4054e61bf49e05009edf26fce4fdc7ec1a9db544784f68e718',
+        'com.google.dagger:dagger:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
+        'com.google.errorprone:error_prone_annotations:2.2.0:error_prone_annotations-2.2.0.jar:6ebd22ca1b9d8ec06d41de8d64e0596981d9607b42035f9ed374f9de271a481a',
         'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
         'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
-        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
-        'com.google.guava:guava:26.0-jre:guava-26.0-jre.jar:a0e9cabad665bc20bcd2b01f108e5fc03f756e13aea80abaadb9f407033bea2c',
-        'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
+        'com.google.guava:failureaccess:1.0.1:failureaccess-1.0.1.jar:a171ee4c734dd2da837e4b16be9df4661afab72a41adaf31eb84dfdaf936ca26',
+        'com.google.guava:guava:27.0.1-jre:guava-27.0.1-jre.jar:e1c814fd04492a27c38e0317eabeaa1b3e950ec8010239e400fe90ad6c9107b4',
+        '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',
         'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
@@ -48,40 +50,41 @@ dependencyVerification {
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
         'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
         'com.sun.xml.fastinfoset:FastInfoset:1.2.13:FastInfoset-1.2.13.jar:27a77db909f3c2833c0b1a37c55af1db06045118ad2eed96ce567b6632bce038',
-        'commons-codec:commons-codec:1.9:commons-codec-1.9.jar:ad19d2601c3abf0b946b5c3a4113e226a8c1e3305e395b90013b78dd94a723ce',
+        'commons-codec:commons-codec:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
         'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
         'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
         'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         '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',
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.apache.commons:commons-compress:1.12:commons-compress-1.12.jar:2c1542faf343185b7cab9c3d55c8ae5471d6d095d3887a4adefdbdf2984dc0b6',
-        'org.apache.httpcomponents:httpclient:4.5.2:httpclient-4.5.2.jar:0dffc621400d6c632f55787d996b8aeca36b30746a716e079a985f24d8074057',
-        'org.apache.httpcomponents:httpcore:4.4.5:httpcore-4.4.5.jar:64d5453874cab7e40a7065cb01a9a9ca1053845a9786b478878b679e0580cec3',
-        'org.apache.httpcomponents:httpmime:4.5.2:httpmime-4.5.2.jar:231a3f7e4962053db2be8461d5422e68fc458a3a7dd7d8ada803a348e21f8f07',
+        'org.apache.httpcomponents:httpclient:4.5.6:httpclient-4.5.6.jar:c03f813195e7a80e3608d0ddd8da80b21696a4c92a6a2298865bf149071551c7',
+        'org.apache.httpcomponents:httpcore:4.4.10:httpcore-4.4.10.jar:78ba1096561957db1b55200a159b648876430342d15d461277e62360da19f6fd',
+        'org.apache.httpcomponents:httpmime:4.5.6:httpmime-4.5.6.jar:0b2b1102c18d3c7e05a77214b9b7501a6f6056174ae5604e0e256776eda7553e',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.9:obfs4proxy-android-0.0.9.zip:9b7e9181535ea8d8bbe8ae6338e08cf4c5fc1e357a779393e0ce49586d459ae0',
-        'org.briarproject:tor-android:0.3.5.8:tor-android-0.3.5.8.zip:42a13a6f185be1a62f42e3f30ce66a3c099ac5ec890a65e7593111b65b44a54a',
+        'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
+        'org.briarproject:tor-android:0.3.5.10:tor-android-0.3.5.10.zip:edd83bf557fcff2105eaa0bdb3f607a6852ebe7360920929ae3039dd5f4774c5',
         '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:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
+        'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
         'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
         'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
         'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.21:kotlin-reflect-1.3.21.jar:a3065c822633191e0a3e3ee12a29bec234fc4b2864a6bb87ef48cce3e9e0c26a',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.21:kotlin-stdlib-common-1.3.21.jar:cea61f7b611895e64f58569a9757fc0ab0d582f107211e1930e0ce2a0add52a7',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.21:kotlin-stdlib-jdk7-1.3.21.jar:a87875604fd42140da6938ae4d35ee61081f4482536efc6d2615b8b626a198af',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.21:kotlin-stdlib-jdk8-1.3.21.jar:5823ed66ac122a1c55442ebca5a209a843ccd87f562edc31a787f3d2e47f74d4',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.21:kotlin-stdlib-1.3.21.jar:38ba2370d9f06f50433e06b2ca775b94473c2e2785f410926079ab793c72b034',
+        'org.jetbrains.kotlin:kotlin-reflect:1.3.50:kotlin-reflect-1.3.50.jar:64583199ea5a54aefd1bd1595288925f784226ee562d1dd279011c6075b3d7a4',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.50:kotlin-stdlib-common-1.3.50.jar:8ce678e88e4ba018b66dacecf952471e4d7dfee156a8a819760a5a5ff29d323c',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.50:kotlin-stdlib-jdk7-1.3.50.jar:9a026639e76212f8d57b86d55b075394c2e009f1979110751d34c05c5f75d57b',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.50:kotlin-stdlib-jdk8-1.3.50.jar:1b351fb6e09c14b55525c74c1f4cf48942eae43c348b7bc764a5e6e423d4da0c',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.3.50:kotlin-stdlib-1.3.50.jar:e6f05746ee0366d0b52825a090fac474dcf44082c9083bbb205bd16976488d6c',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',

bramble-api/build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.19"
+	implementation "com.google.dagger:dagger:2.24"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
 	testImplementation 'junit:junit:4.12'

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -0,0 +1,49 @@
+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

@@ -0,0 +1,102 @@
+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 a connection with the given contact over the given transport.
+	 * <p>
+	 * Broadcasts {@link ConnectionOpenedEvent}. Also broadcasts
+	 * {@link ContactConnectedEvent} if this is the only connection with the
+	 * contact.
+	 */
+	void registerConnection(ContactId c, TransportId t,
+			InterruptibleConnection conn, boolean incoming);
+
+	/**
+	 * 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 #registerConnection(ContactId, TransportId,
+	 * InterruptibleConnection, boolean)}.
+	 * <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

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

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

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

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

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

@@ -1,47 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-
-/**
- * A task for conducting a contact information exchange with a remote peer.
- */
-@NotNullByDefault
-public interface ContactExchangeTask {
-
-	/**
-	 * The current version of the contact exchange protocol.
-	 */
-	byte PROTOCOL_VERSION = 1;
-
-	/**
-	 * Label for deriving Alice's header key from the master secret.
-	 */
-	String ALICE_KEY_LABEL =
-			"org.briarproject.bramble.contact/ALICE_HEADER_KEY";
-
-	/**
-	 * Label for deriving Bob's header key from the master secret.
-	 */
-	String BOB_KEY_LABEL = "org.briarproject.bramble.contact/BOB_HEADER_KEY";
-
-	/**
-	 * Label for deriving Alice's key binding nonce from the master secret.
-	 */
-	String ALICE_NONCE_LABEL = "org.briarproject.bramble.contact/ALICE_NONCE";
-
-	/**
-	 * Label for deriving Bob's key binding nonce from the master secret.
-	 */
-	String BOB_NONCE_LABEL = "org.briarproject.bramble.contact/BOB_NONCE";
-
-	/**
-	 * Exchanges contact information with a remote peer.
-	 */
-	void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
-			DuplexTransportConnection conn, TransportId transportId,
-			boolean alice);
-}

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

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

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

@@ -1,7 +1,13 @@
 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;
@@ -9,12 +15,11 @@ 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;
 
-import static org.briarproject.bramble.api.contact.PendingContact.PendingContactState.FAILED;
-
 @NotNullByDefault
 public interface ContactManager {
 
@@ -27,61 +32,119 @@ public interface ContactManager {
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores transport keys for each transport, and returns an ID
-	 * for the contact.
+	 * derives and stores rotation mode transport keys for each transport, and
+	 * returns an ID for the contact.
 	 *
-	 * @param alice true if the local party is Alice
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			SecretKey master, long timestamp, boolean alice, boolean verified,
+			SecretKey rootKey, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
+	/**
+	 * Stores a contact associated with the given local and remote pseudonyms,
+	 * replacing the given pending contact, derives and stores handshake mode
+	 * and rotation mode transport keys for each transport, and returns an ID
+	 * for the contact.
+	 *
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
+	 * @throws GeneralSecurityException If the pending contact's handshake
+	 * public key is invalid
+	 */
+	ContactId addContact(Transaction txn, PendingContactId p, Author remote,
+			AuthorId local, SecretKey rootKey, long timestamp, boolean alice,
+			boolean verified, boolean active)
+			throws DbException, GeneralSecurityException;
+
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms
 	 * and returns an ID for the contact.
+	 *
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			boolean verified, boolean active) throws DbException;
+			boolean verified) throws DbException;
 
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
-	 * derives and stores transport keys for each transport, and returns an ID
-	 * for the contact.
+	 * derives and stores rotation mode transport keys for each transport, and
+	 * returns an ID for the contact.
 	 *
-	 * @param alice true if the local party is Alice
+	 * @param rootKey The root key for a set of rotation mode transport keys
+	 * @param timestamp The timestamp for deriving rotation mode transport
+	 * keys from the root key
+	 * @param alice True if the local party is Alice
+	 * @param verified True if the contact's identity has been verified, which
+	 * is true if the contact was added in person or false if the contact was
+	 * introduced or added remotely
+	 * @param active True if the rotation mode transport keys can be used for
+	 * outgoing streams
 	 */
-	ContactId addContact(Author remote, AuthorId local, SecretKey master,
+	ContactId addContact(Author remote, AuthorId local, SecretKey rootKey,
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException;
 
 	/**
-	 * Returns the static link that needs to be sent to the contact to be added.
+	 * Returns the handshake link that needs to be sent to a contact we want
+	 * to add.
 	 */
-	String getRemoteContactLink();
+	String getHandshakeLink() throws DbException;
 
 	/**
-	 * Returns true if the given link is syntactically valid.
-	 */
-	boolean isValidRemoteContactLink(String link);
-
-	/**
-	 * Requests a new contact to be added via the given {@code link}.
+	 * Creates a {@link PendingContact} from the given handshake link and
+	 * alias, adds it to the database and returns it.
 	 *
-	 * @param link The link received from the contact we want to add.
-	 * @param alias The alias the user has given this contact.
-	 * @return A PendingContact representing the contact to be added.
+	 * @param link The handshake link received from the pending contact
+	 * @param alias The alias the user has given this pending contact
+	 * @throws UnsupportedVersionException If the link uses a format version
+	 * that is not supported
+	 * @throws FormatException If the link is invalid
+	 * @throws GeneralSecurityException If the pending contact's handshake
+	 * public key is invalid
+	 * @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 addRemoteContactRequest(String link, String alias);
+	PendingContact addPendingContact(String link, String alias)
+			throws DbException, FormatException, GeneralSecurityException,
+			ContactExistsException, PendingContactExistsException;
 
 	/**
-	 * Returns a list of {@link PendingContact}s.
+	 * Returns the pending contact with the given ID.
 	 */
-	Collection<PendingContact> getPendingContacts();
+	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
 
 	/**
-	 * Removes a {@link PendingContact} that is in state {@link FAILED}.
+	 * Returns a list of {@link PendingContact PendingContacts} and their
+	 * {@link PendingContactState states}.
 	 */
-	void removePendingContact(PendingContact pendingContact);
+	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
+			throws DbException;
+
+	/**
+	 * Removes a {@link PendingContact}.
+	 */
+	void removePendingContact(PendingContactId p) throws DbException;
 
 	/**
 	 * Returns the contact with the given ID.
@@ -89,27 +152,32 @@ public interface ContactManager {
 	Contact getContact(ContactId c) throws DbException;
 
 	/**
-	 * Returns the contact with the given remoteAuthorId
-	 * that was added by the LocalAuthor with the given localAuthorId
+	 * Returns the contact with the given ID.
+	 */
+	Contact getContact(Transaction txn, ContactId c) throws DbException;
+
+	/**
+	 * Returns the contact with the given {@code remoteAuthorId}
+	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
 	 *
-	 * @throws org.briarproject.bramble.api.db.NoSuchContactException
+	 * @throws NoSuchContactException If the contact is not in the database
 	 */
 	Contact getContact(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
 
 	/**
-	 * Returns the contact with the given remoteAuthorId
-	 * that was added by the LocalAuthor with the given localAuthorId
+	 * Returns the contact with the given {@code remoteAuthorId}
+	 * that belongs to the local pseudonym with the given {@code localAuthorId}.
 	 *
-	 * @throws org.briarproject.bramble.api.db.NoSuchContactException
+	 * @throws NoSuchContactException If the contact is not in the database
 	 */
 	Contact getContact(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Returns all active contacts.
+	 * Returns all contacts.
 	 */
-	Collection<Contact> getActiveContacts() throws DbException;
+	Collection<Contact> getContacts() throws DbException;
 
 	/**
 	 * Removes a contact and all associated state.
@@ -122,31 +190,27 @@ public interface ContactManager {
 	void removeContact(Transaction txn, ContactId c) throws DbException;
 
 	/**
-	 * Marks a contact as active or inactive.
-	 */
-	void setContactActive(Transaction txn, ContactId c, boolean active)
-			throws DbException;
-
-	/**
-	 * Sets an alias name for the contact or unsets it if alias is null.
+	 * Sets an alias for the contact or unsets it if {@code alias} is null.
 	 */
 	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Sets an alias name for the contact or unsets it if alias is null.
+	 * Sets an alias for the contact or unsets it if {@code alias} is null.
 	 */
 	void setContactAlias(ContactId c, @Nullable String alias)
 			throws DbException;
 
 	/**
-	 * Return true if a contact with this name and public key already exists
+	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException;
 
 	/**
-	 * Return true if a contact with this name and public key already exists
+	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
+	 * the local pseudonym with this {@code localAuthorId}.
 	 */
 	boolean contactExists(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException;
@@ -163,8 +227,20 @@ public interface ContactManager {
 
 	interface ContactHook {
 
+		/**
+		 * Called when a contact is being added.
+		 *
+		 * @param txn A read-write transaction
+		 * @param c The contact that is being added
+		 */
 		void addingContact(Transaction txn, Contact c) throws DbException;
 
+		/**
+		 * Called when a contact is being removed
+		 *
+		 * @param txn A read-write transaction
+		 * @param c The contact that is being removed
+		 */
 		void removingContact(Transaction txn, Contact c) throws DbException;
 	}
 }

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

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

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

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

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

@@ -1,5 +1,6 @@
 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;
@@ -8,34 +9,31 @@ import javax.annotation.concurrent.Immutable;
 @NotNullByDefault
 public class PendingContact {
 
-	public enum PendingContactState {
-		WAITING_FOR_CONNECTION,
-		CONNECTED,
-		ADDING_CONTACT,
-		FAILED
-	}
-
 	private final PendingContactId id;
+	private final PublicKey publicKey;
 	private final String alias;
-	private final PendingContactState state;
 	private final long timestamp;
 
-	public PendingContact(PendingContactId id, String alias,
-			PendingContactState state, long timestamp) {
+	public PendingContact(PendingContactId id, PublicKey publicKey,
+			String alias, long timestamp) {
 		this.id = id;
+		this.publicKey = publicKey;
 		this.alias = alias;
-		this.state = state;
 		this.timestamp = timestamp;
 	}
 
+	public PendingContactId getId() {
+		return id;
+	}
+
+	public PublicKey getPublicKey() {
+		return publicKey;
+	}
+
 	public String getAlias() {
 		return alias;
 	}
 
-	public PendingContactState getState() {
-		return state;
-	}
-
 	public long getTimestamp() {
 		return timestamp;
 	}
@@ -50,5 +48,4 @@ public class PendingContact {
 		return o instanceof PendingContact &&
 				id.equals(((PendingContact) o).id);
 	}
-
 }

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

@@ -1,11 +1,25 @@
 package org.briarproject.bramble.api.contact;
 
 import org.briarproject.bramble.api.UniqueId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a
+ * {@link PendingContact}.
+ */
+@ThreadSafe
+@NotNullByDefault
 public class PendingContactId extends UniqueId {
 
 	public PendingContactId(byte[] id) {
 		super(id);
 	}
 
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof PendingContactId && super.equals(o);
+	}
 }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -1,7 +1,7 @@
 package org.briarproject.bramble.api.contact.event;
 
-import org.briarproject.bramble.api.contact.PendingContact.PendingContactState;
 import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.contact.PendingContactState;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 

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

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

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

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

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

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

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

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

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

@@ -0,0 +1,29 @@
+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/KeyAgreementCrypto.java

@@ -2,7 +2,7 @@ package org.briarproject.bramble.api.crypto;
 
 /**
  * Crypto operations for the key agreement protocol - see
- * https://code.briarproject.org/akwizgran/briar-spec/blob/master/protocols/BQP.md
+ * https://code.briarproject.org/briar/briar-spec/blob/master/protocols/BQP.md
  */
 public interface KeyAgreementCrypto {
 

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

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

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

@@ -0,0 +1,23 @@
+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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -1,15 +1,29 @@
 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();
 
-	long getMaxSize();
+	/**
+	 * 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/EventAction.java

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

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

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

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

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

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

@@ -0,0 +1,21 @@
+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/TaskAction.java

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -0,0 +1,15 @@
+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/KeyAgreementConstants.java

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -1,23 +0,0 @@
-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

@@ -4,10 +4,10 @@ public interface LanTcpConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.lan");
 
-	// a transport property (shared with contacts)
+	// Transport properties (shared with contacts)
 	String PROP_IP_PORTS = "ipPorts";
+	String PROP_PORT = "port";
 
-	// a local setting
+	// A local setting
 	String PREF_LAN_IP_PORTS = "ipPorts";
-
 }

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

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

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

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

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

@@ -5,6 +5,8 @@ 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 {
@@ -14,4 +16,11 @@ 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

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

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

@@ -4,6 +4,7 @@ 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;
@@ -14,6 +15,8 @@ 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;
@@ -44,6 +47,11 @@ public abstract class AbstractDuplexTransportConnection
 		return writer;
 	}
 
+	@Override
+	public TransportProperties getRemoteProperties() {
+		return remote;
+	}
+
 	private class Reader implements TransportConnectionReader {
 
 		@Override