Only add Tor transport properties to our social backup

Social backup restore activity

See merge request briar/briar!1444

.gitlab-ci.yml

@@ -1,52 +1,30 @@
 image: briar/ci-image-android:latest
 
 stages:
-  - test
-  - optional_tests
-  - check_reproducibility
+- test
+- optional_tests
+- check_reproducibility
 
-.base-test:
+test:
+  stage: test
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
+
   cache:
-    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches
+
+  script:
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources
+
   after_script:
-    # these file change every time and should not be cached
+    # these file change every time but should not be cached
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
-test:
-  extends: .base-test
-  stage: test
-  script:
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check
-
-android test:
-  extends: .base-test
-  stage: optional_tests
-  image: briar/ci-image-android-emulator:latest
-  script:
-    # start emulator first, so it can fail early
-    - start-emulator.sh
-    # run normal and screenshot tests together (exclude Large tests)
-    - ./gradlew -Djava.security.egd=file:/dev/urandom connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.notAnnotation=androidx.test.filters.LargeTest
-  artifacts:
-    name: "${CI_PROJECT_PATH}_${CI_JOB_STAGE}_${CI_COMMIT_REF_NAME}_${CI_COMMIT_SHA}"
-    paths:
-      - kernel.log
-      - logcat.txt
-    expire_in: 3 days
-    when: on_failure
-  when: manual
-  except:
-    - tags
-  tags:
-    - kvm
 
 test_reproducible:
   stage: check_reproducibility
@@ -62,7 +40,6 @@ test_reproducible:
     - export GRADLE_USER_HOME=$PWD/.gradle
 
   cache:
-    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches

.idea/codeStyles/Project.xml

@@ -31,15 +31,6 @@
       <option name="PACKAGES_TO_USE_STAR_IMPORTS">
         <value />
       </option>
-      <option name="PACKAGES_IMPORT_LAYOUT">
-        <value>
-          <package name="" alias="false" withSubpackages="true" />
-          <package name="java" alias="false" withSubpackages="true" />
-          <package name="javax" alias="false" withSubpackages="true" />
-          <package name="kotlin" alias="false" withSubpackages="true" />
-          <package name="" alias="true" withSubpackages="true" />
-        </value>
-      </option>
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT_FOR_MEMBERS" value="2147483647" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />

.idea/runConfigurations/Instrumentation_Tests__destroys_DB_.xml

@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Instrumentation Tests (destroys DB)" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests">
-    <module name="briar.briar-android" />
-    <option name="TESTING_TYPE" value="1" />
-    <option name="METHOD_NAME" value="" />
-    <option name="CLASS_NAME" value="" />
-    <option name="PACKAGE_NAME" value="org.briarproject.briar.android" />
-    <option name="INSTRUMENTATION_RUNNER_CLASS" value="" />
-    <option name="EXTRA_OPTIONS" value="-e notAnnotation androidx.test.filters.LargeTest" />
-    <option name="INCLUDE_GRADLE_EXTRA_OPTIONS" value="true" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="DEVICE_AND_SNAPSHOT_COMBO_BOX" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_CPU_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_CPU_PROFILING_CONFIGURATION_NAME" value="Sample Java Methods" />
-      <option name="STARTUP_NATIVE_MEMORY_PROFILING_ENABLED" value="false" />
-      <option name="NATIVE_MEMORY_SAMPLE_RATE_BYTES" value="2048" />
-    </Profilers>
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
-  </configuration>
-</component>

bramble-android/build.gradle

@@ -15,8 +15,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10220
-		versionName "1.2.20"
+		versionCode 10218
+		versionName "1.2.18"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

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

@@ -2,6 +2,7 @@ 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.Identity;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
@@ -43,6 +44,17 @@ public interface AccountManager {
 	 */
 	boolean createAccount(String name, String password);
 
+	/**
+	 * Restores a given identity by registering it with the
+	 * {@link IdentityManager}.  Creates a database key, encrypts it with the
+	 * given password and stores it on disk. {@link #accountExists()} will
+	 * return true after this method returns true.
+ 	 * @param identity
+	 * @param password
+	 * @return
+	 */
+	boolean restoreAccount(Identity identity, String password);
+
 	/**
 	 * Deletes all account state from disk. {@link #accountExists()} will
 	 * return false after this method returns.

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

@@ -1,6 +1,6 @@
-package org.briarproject.bramble.contact;
+package org.briarproject.bramble.api.contact;
 
-interface ContactExchangeConstants {
+public interface ContactExchangeConstants {
 
 	/**
 	 * The current version of the contact exchange protocol.

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

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.contact;
+package org.briarproject.bramble.api.contact;
 
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 @NotNullByDefault
-interface ContactExchangeCrypto {
+public interface ContactExchangeCrypto {
 
 	/**
 	 * Derives the header key for a contact exchange stream from the master key.

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

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

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.api.contact;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.UnsupportedVersionException;
+import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DbException;
@@ -48,6 +49,10 @@ public interface ContactManager {
 			SecretKey rootKey, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
+	ContactId addContact(Transaction txn, Author remote, AuthorId local,
+			PublicKey handshake, boolean verified)
+			throws DbException, GeneralSecurityException;
+
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
 	 * replacing the given pending contact, derives and stores handshake mode
@@ -205,6 +210,18 @@ public interface ContactManager {
 	void setContactAlias(ContactId c, @Nullable String alias)
 			throws DbException;
 
+	/**
+	 * Sets the contact's handshake public key
+	 */
+	void setHandshakePublicKey(Transaction txn, ContactId c,
+			PublicKey handshakePublicKey) throws DbException;
+
+	/**
+	 * Sets the contact's handshake public key
+	 */
+	void setHandshakePublicKey(ContactId c, PublicKey handshakePublicKey)
+			throws DbException;
+
 	/**
 	 * Returns true if a contact with this {@code remoteAuthorId} belongs to
 	 * the local pseudonym with this {@code localAuthorId}.

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

@@ -24,6 +24,19 @@ public interface HandshakeManager {
 	HandshakeResult handshake(PendingContactId p, InputStream in,
 			StreamWriter out) throws DbException, IOException;
 
+	/**
+	 * Handshakes with the given 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(ContactId c, InputStream in, StreamWriter out)
+			throws DbException, IOException;
+
 	class HandshakeResult {
 
 		private final SecretKey masterKey;

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

@@ -1,12 +1,11 @@
-package org.briarproject.bramble.crypto;
+package org.briarproject.bramble.api.crypto;
 
-import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
 
 @NotNullByDefault
-interface AuthenticatedCipher {
+public interface AuthenticatedCipher {
 
 	/**
 	 * Initializes this cipher for encryption or decryption with a key and an

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

@@ -546,6 +546,11 @@ public interface DatabaseComponent extends TransactionManager {
 	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
 			throws DbException;
 
+	/**
+	 * Sets the remote handshake public key for a given contact
+	 */
+	void setHandshakePublicKey(Transaction txn, ContactId c, PublicKey handshakePublicKey) throws DbException;
+
 	/**
 	 * Sets the given group's visibility to the given contact.
 	 */

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

@@ -26,6 +26,11 @@ public interface IdentityManager {
 	 */
 	void registerIdentity(Identity i);
 
+	/**
+	 * Returns the cached local identity or loads it from the database.
+	 */
+	Identity getIdentity(Transaction txn) throws DbException;
+
 	/**
 	 * Returns the cached local identity or loads it from the database.
 	 */

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

@@ -74,6 +74,13 @@ public interface TransportPropertyManager {
 	TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException;
 
+	/**
+	 * Returns the remote transport properties for the given contact and
+	 * transport.
+	 */
+	TransportProperties getRemoteProperties(Transaction txn, ContactId c,
+			TransportId t) throws DbException;
+
 	/**
 	 * Merges the given properties with the existing local properties for the
 	 * given transport.

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

@@ -35,6 +35,20 @@ public interface KeyManager {
 			ContactId c, SecretKey rootKey, long timestamp, boolean alice,
 			boolean active) throws DbException;
 
+	/**
+	 * Derives and stores a set of rotation mode transport keys for
+	 * communicating with the given contact over each transport and returns the
+	 * key set IDs.
+	 * <p/>
+	 * {@link StreamContext StreamContexts} for the contact can be created
+	 * after this method has returned.
+	 *
+	 * @param alice True if the local party is Alice
+	 * @param active Whether the derived keys can be used for outgoing streams
+	 */
+	Map<TransportId, KeySetId> addRotationKeys(ContactId c, SecretKey rootKey,
+			long timestamp, boolean alice, boolean active) throws DbException;
+
 	/**
 	 * Informs the key manager that a new contact has been added. Derives and
 	 * stores a set of handshake mode transport keys for communicating with the

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

@@ -176,6 +176,18 @@ class AccountManagerImpl implements AccountManager {
 		}
 	}
 
+	public boolean restoreAccount(Identity identity, String password) {
+		synchronized (stateChangeLock) {
+			if (hasDatabaseKey())
+				throw new AssertionError("Already have a database key");
+			identityManager.registerIdentity(identity);
+			SecretKey key = crypto.generateSecretKey();
+			if (!encryptAndStoreDatabaseKey(key, password)) return false;
+			databaseKey = key;
+			return true;
+		}
+	}
+
 	@GuardedBy("stateChangeLock")
 	private boolean encryptAndStoreDatabaseKey(SecretKey key, String password) {
 		byte[] plaintext = key.getBytes();

bramble-core/src/main/java/org/briarproject/bramble/connection/ConnectionManagerImpl.java

@@ -76,7 +76,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 		ioExecutor.execute(new IncomingDuplexSyncConnection(keyManager,
 				connectionRegistry, streamReaderFactory, streamWriterFactory,
 				syncSessionFactory, transportPropertyManager, ioExecutor,
-				t, d));
+				t, d, handshakeManager));
 	}
 
 	@Override
@@ -101,7 +101,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 		ioExecutor.execute(new OutgoingDuplexSyncConnection(keyManager,
 				connectionRegistry, streamReaderFactory, streamWriterFactory,
 				syncSessionFactory, transportPropertyManager, ioExecutor,
-				secureRandom, c, t, d));
+				secureRandom, handshakeManager, c, t, d));
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/connection/DuplexSyncConnection.java

@@ -3,6 +3,7 @@ package org.briarproject.bramble.connection;
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
 import org.briarproject.bramble.api.connection.InterruptibleConnection;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.HandshakeManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;

bramble-core/src/main/java/org/briarproject/bramble/connection/IncomingDuplexSyncConnection.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.connection;
 
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.HandshakeManager;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -13,9 +14,11 @@ import org.briarproject.bramble.api.sync.SyncSessionFactory;
 import org.briarproject.bramble.api.transport.KeyManager;
 import org.briarproject.bramble.api.transport.StreamContext;
 import org.briarproject.bramble.api.transport.StreamReaderFactory;
+import org.briarproject.bramble.api.transport.StreamWriter;
 import org.briarproject.bramble.api.transport.StreamWriterFactory;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.concurrent.Executor;
 
 import static java.util.logging.Level.WARNING;
@@ -24,6 +27,10 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 @NotNullByDefault
 class IncomingDuplexSyncConnection extends DuplexSyncConnection
 		implements Runnable {
+	private final HandshakeManager handshakeManager;
+
+	// FIXME: Exchange timestamp as part of handshake protocol?
+	private static final long TIMESTAMP = 1617235200; // 1 April 2021 00:00 UTC
 
 	IncomingDuplexSyncConnection(KeyManager keyManager,
 			ConnectionRegistry connectionRegistry,
@@ -32,14 +39,18 @@ class IncomingDuplexSyncConnection extends DuplexSyncConnection
 			SyncSessionFactory syncSessionFactory,
 			TransportPropertyManager transportPropertyManager,
 			Executor ioExecutor, TransportId transportId,
-			DuplexTransportConnection connection) {
+			DuplexTransportConnection connection,
+			HandshakeManager handshakeManager) {
 		super(keyManager, connectionRegistry, streamReaderFactory,
 				streamWriterFactory, syncSessionFactory,
 				transportPropertyManager, ioExecutor, transportId, connection);
+		this.handshakeManager = handshakeManager;
 	}
 
 	@Override
 	public void run() {
+		LOG.info("Running IncomingDuplexSyncConnection on transport " +
+				transportId.getString());
 		// Read and recognise the tag
 		StreamContext ctx = recogniseTag(reader, transportId);
 		if (ctx == null) {
@@ -54,10 +65,22 @@ class IncomingDuplexSyncConnection extends DuplexSyncConnection
 			return;
 		}
 		if (ctx.isHandshakeMode()) {
-			// TODO: Support handshake mode for contacts
-			LOG.warning("Received handshake tag, expected rotation mode");
-			onReadError(true);
-			return;
+			if (!performHandshake(ctx, contactId)) {
+				LOG.warning("Handshake failed");
+				return;
+			}
+			// Allocate a rotation mode stream context
+			ctx = allocateStreamContext(contactId, transportId);
+			if (ctx == null) {
+				LOG.warning("Could not allocate stream context");
+				onWriteError();
+				return;
+			}
+			if (ctx.isHandshakeMode()) {
+				LOG.warning("Got handshake mode context after handshaking");
+				onWriteError();
+				return;
+			}
 		}
 		connectionRegistry.registerIncomingConnection(contactId, transportId,
 				this);
@@ -103,5 +126,35 @@ class IncomingDuplexSyncConnection extends DuplexSyncConnection
 			onWriteError();
 		}
 	}
+
+	private boolean performHandshake(StreamContext ctxIn, ContactId contactId) {
+		LOG.info("Performing handshake (Incoming)");
+		// Allocate the outgoing stream context
+		StreamContext ctxOut =
+				allocateStreamContext(contactId, transportId);
+		if (ctxOut == null) {
+			LOG.warning("Could not allocate stream context");
+			onReadError(true);
+			return false;
+		}
+		try {
+			InputStream in = streamReaderFactory.createStreamReader(
+					reader.getInputStream(), ctxIn);
+			// Flush the output stream to send the outgoing stream header
+			StreamWriter out = streamWriterFactory.createStreamWriter(
+					writer.getOutputStream(), ctxOut);
+			out.getOutputStream().flush();
+			HandshakeManager.HandshakeResult result =
+					handshakeManager.handshake(contactId, in, out);
+			keyManager.addRotationKeys(contactId, result.getMasterKey(),
+					TIMESTAMP, result.isAlice(), true);
+			LOG.info("Rotation keys added");
+			return true;
+		} catch (IOException | DbException e) {
+			logException(LOG, WARNING, e);
+			onReadError(true);
+			return false;
+		}
+	}
 }
 

bramble-core/src/main/java/org/briarproject/bramble/connection/OutgoingDuplexSyncConnection.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.connection;
 
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.HandshakeManager;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -14,9 +15,11 @@ import org.briarproject.bramble.api.sync.SyncSessionFactory;
 import org.briarproject.bramble.api.transport.KeyManager;
 import org.briarproject.bramble.api.transport.StreamContext;
 import org.briarproject.bramble.api.transport.StreamReaderFactory;
+import org.briarproject.bramble.api.transport.StreamWriter;
 import org.briarproject.bramble.api.transport.StreamWriterFactory;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
 
@@ -28,26 +31,38 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class OutgoingDuplexSyncConnection extends DuplexSyncConnection
 		implements Runnable {
 
+	// FIXME: Exchange timestamp as part of handshake protocol?
+	private static final long TIMESTAMP = 1617235200; // 1 April 2021 00:00 UTC
+
 	private final SecureRandom secureRandom;
+	private final HandshakeManager handshakeManager;
 	private final ContactId contactId;
 
-	OutgoingDuplexSyncConnection(KeyManager keyManager,
+	OutgoingDuplexSyncConnection(
+			KeyManager keyManager,
 			ConnectionRegistry connectionRegistry,
 			StreamReaderFactory streamReaderFactory,
 			StreamWriterFactory streamWriterFactory,
 			SyncSessionFactory syncSessionFactory,
 			TransportPropertyManager transportPropertyManager,
-			Executor ioExecutor, SecureRandom secureRandom, ContactId contactId,
-			TransportId transportId, DuplexTransportConnection connection) {
+			Executor ioExecutor,
+			SecureRandom secureRandom,
+			HandshakeManager handshakeManager,
+			ContactId contactId,
+			TransportId transportId,
+			DuplexTransportConnection connection) {
 		super(keyManager, connectionRegistry, streamReaderFactory,
 				streamWriterFactory, syncSessionFactory,
 				transportPropertyManager, ioExecutor, transportId, connection);
 		this.secureRandom = secureRandom;
+		this.handshakeManager = handshakeManager;
 		this.contactId = contactId;
 	}
 
 	@Override
 	public void run() {
+		LOG.info("Running OutgoingDuplexSyncConnection on transport " +
+				transportId.getString());
 		// Allocate a stream context
 		StreamContext ctx = allocateStreamContext(contactId, transportId);
 		if (ctx == null) {
@@ -56,10 +71,22 @@ class OutgoingDuplexSyncConnection extends DuplexSyncConnection
 			return;
 		}
 		if (ctx.isHandshakeMode()) {
-			// TODO: Support handshake mode for contacts
-			LOG.warning("Cannot use handshake mode stream context");
-			onWriteError();
-			return;
+			if (!performHandshake(ctx)) {
+				LOG.warning("Handshake failed");
+				return;
+			}
+			// Allocate a rotation mode stream context
+			ctx = allocateStreamContext(contactId, transportId);
+			if (ctx == null) {
+				LOG.warning("Could not allocate stream context");
+				onWriteError();
+				return;
+			}
+			if (ctx.isHandshakeMode()) {
+				LOG.warning("Got handshake mode context after handshaking");
+				onWriteError();
+				return;
+			}
 		}
 		// Start the incoming session on another thread
 		Priority priority = generatePriority();
@@ -127,6 +154,59 @@ class OutgoingDuplexSyncConnection extends DuplexSyncConnection
 		}
 	}
 
+	private boolean performHandshake(StreamContext ctxOut) {
+		LOG.info("Performing handshake (Outgoing)");
+		// Flush the output stream to send the outgoing stream header
+		StreamWriter out;
+		try {
+			out = streamWriterFactory.createStreamWriter(
+					writer.getOutputStream(), ctxOut);
+			out.getOutputStream().flush();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			onWriteError();
+			return false;
+		}
+		// Read and recognise the tag
+		StreamContext ctxIn = recogniseTag(reader, transportId);
+		// Unrecognised tags are suspicious in this case
+		if (ctxIn == null) {
+			LOG.warning("Unrecognised tag for returning stream");
+			onReadError();
+			return false;
+		}
+		// Check that the stream comes from the expected contact
+		ContactId inContactId = ctxIn.getContactId();
+		if (contactId == null) {
+			LOG.warning("Expected contact tag, got rendezvous tag");
+			onReadError();
+			return false;
+		}
+		if (!inContactId.equals(contactId)) {
+			LOG.warning("Wrong contact ID for returning stream");
+			onReadError();
+			return false;
+		}
+		// TODO: Register the connection, close it if it's redundant
+		// Handshake and exchange contacts
+		try {
+			InputStream in = streamReaderFactory.createStreamReader(
+					reader.getInputStream(), ctxIn);
+			HandshakeManager.HandshakeResult result =
+					handshakeManager.handshake(contactId, in, out);
+			keyManager.addRotationKeys(contactId, result.getMasterKey(),
+					TIMESTAMP, result.isAlice(), true);
+			LOG.info("Rotation keys added");
+			return true;
+		} catch (IOException | DbException e) {
+			logException(LOG, WARNING, e);
+			onWriteError();
+			return false;
+		} finally {
+			// TODO: Unregister the connection
+		}
+	}
+
 	private void onReadError() {
 		// 'Recognised' is always true for outgoing connections
 		onReadError(true);

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.contact;
 
+import org.briarproject.bramble.api.contact.ContactExchangeCrypto;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
@@ -10,12 +11,12 @@ import java.security.GeneralSecurityException;
 
 import javax.inject.Inject;
 
-import static org.briarproject.bramble.contact.ContactExchangeConstants.ALICE_KEY_LABEL;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.ALICE_NONCE_LABEL;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.BOB_KEY_LABEL;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.BOB_NONCE_LABEL;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.PROTOCOL_VERSION;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.SIGNING_LABEL;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.ALICE_KEY_LABEL;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.ALICE_NONCE_LABEL;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.BOB_KEY_LABEL;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.BOB_NONCE_LABEL;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.PROTOCOL_VERSION;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.SIGNING_LABEL;
 
 @NotNullByDefault
 class ContactExchangeCryptoImpl implements ContactExchangeCrypto {

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.Predicate;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactExchangeCrypto;
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
@@ -47,8 +48,8 @@ import javax.inject.Inject;
 
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
-import static org.briarproject.bramble.contact.ContactExchangeConstants.PROTOCOL_VERSION;
-import static org.briarproject.bramble.contact.ContactExchangeRecordTypes.CONTACT_INFO;
+import static org.briarproject.bramble.api.contact.ContactExchangeConstants.PROTOCOL_VERSION;
+import static org.briarproject.bramble.api.contact.ContactExchangeRecordTypes.CONTACT_INFO;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 
@@ -81,7 +82,8 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 	private final ContactManager contactManager;
 	private final IdentityManager identityManager;
 	private final TransportPropertyManager transportPropertyManager;
-	private final ContactExchangeCrypto contactExchangeCrypto;
+	private final org.briarproject.bramble.api.contact.ContactExchangeCrypto
+			contactExchangeCrypto;
 	private final StreamReaderFactory streamReaderFactory;
 	private final StreamWriterFactory streamWriterFactory;
 

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

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

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

@@ -9,6 +9,7 @@ import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.contact.PendingContactState;
 import org.briarproject.bramble.api.contact.event.PendingContactStateChangedEvent;
+import org.briarproject.bramble.api.crypto.CryptoConstants;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
@@ -119,6 +120,18 @@ class ContactManagerImpl implements ContactManager, EventListener {
 						verified, active));
 	}
 
+	@Override
+	public ContactId addContact(Transaction txn, Author remote, AuthorId local,
+			PublicKey handshake, boolean verified)
+			throws DbException, GeneralSecurityException {
+		ContactId c = db.addContact(txn, remote, local, handshake, verified);
+		Contact contact = db.getContact(txn, c);
+		KeyPair ourKeyPair = identityManager.getHandshakeKeys(txn);
+		keyManager.addContact(txn, c, handshake, ourKeyPair);
+		for (ContactHook hook : hooks) hook.addingContact(txn, contact);
+		return c;
+	}
+
 	@Override
 	public String getHandshakeLink() throws DbException {
 		KeyPair keyPair = db.transactionWithResult(true,
@@ -234,6 +247,23 @@ class ContactManagerImpl implements ContactManager, EventListener {
 		db.transaction(false, txn -> setContactAlias(txn, c, alias));
 	}
 
+	@Override
+	public void setHandshakePublicKey(Transaction txn, ContactId c,
+			PublicKey handshakePublicKey) throws DbException {
+		if (handshakePublicKey.getKeyType() !=
+				CryptoConstants.KEY_TYPE_AGREEMENT) {
+			throw new IllegalArgumentException();
+		}
+		db.setHandshakePublicKey(txn, c, handshakePublicKey);
+	}
+
+	@Override
+	public void setHandshakePublicKey(ContactId c, PublicKey handshakePublicKey)
+			throws DbException {
+		db.transaction(false,
+				txn -> setHandshakePublicKey(txn, c, handshakePublicKey));
+	}
+
 	@Override
 	public boolean contactExists(Transaction txn, AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException {

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.contact;
 
+import org.briarproject.bramble.api.contact.ContactExchangeCrypto;
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.HandshakeManager;

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

@@ -3,6 +3,8 @@ package org.briarproject.bramble.contact;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.Predicate;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.HandshakeManager;
 import org.briarproject.bramble.api.contact.PendingContact;
@@ -88,6 +90,27 @@ class HandshakeManagerImpl implements HandshakeManager {
 		});
 		PublicKey theirStaticPublicKey = keys.getFirst();
 		KeyPair ourStaticKeyPair = keys.getSecond();
+		return handshake(theirStaticPublicKey, ourStaticKeyPair, in, out);
+	}
+
+	@Override
+	public HandshakeResult handshake(ContactId c, InputStream in,
+			StreamWriter out) throws DbException, IOException {
+		Pair<PublicKey, KeyPair> keys = db.transactionWithResult(true, txn -> {
+			Contact contact = contactManager.getContact(txn, c);
+			PublicKey handshakePublicKey = contact.getHandshakePublicKey();
+			if (handshakePublicKey == null) throw new DbException();
+			KeyPair keyPair = identityManager.getHandshakeKeys(txn);
+			return new Pair<>(handshakePublicKey, keyPair);
+		});
+		PublicKey theirStaticPublicKey = keys.getFirst();
+		KeyPair ourStaticKeyPair = keys.getSecond();
+		return handshake(theirStaticPublicKey, ourStaticKeyPair, in, out);
+	}
+
+	private HandshakeResult handshake(PublicKey theirStaticPublicKey,
+			KeyPair ourStaticKeyPair, InputStream in, StreamWriter out)
+			throws IOException {
 		boolean alice = transportCrypto.isAlice(theirStaticPublicKey,
 				ourStaticKeyPair);
 		RecordReader recordReader = recordReaderFactory.createRecordReader(in);

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

@@ -6,6 +6,7 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyPair;

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamDecrypter;
 import org.briarproject.bramble.api.crypto.StreamDecrypterFactory;

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamDecrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;

bramble-core/src/main/java/org/briarproject/bramble/crypto/XSalsa20Poly1305AuthenticatedCipher.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.spongycastle.crypto.DataLengthException;

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

@@ -32,6 +32,7 @@ import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeySet;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
+import java.sql.Connection;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -695,6 +696,11 @@ interface Database<T> {
 	void setHandshakeKeyPair(T txn, AuthorId local, PublicKey publicKey,
 			PrivateKey privateKey) throws DbException;
 
+	/**
+	 * Sets the handshake public key for a given contact
+	 */
+	void setHandshakePublicKey(T txn, ContactId c, PublicKey handshakePublicKey) throws DbException;
+
 	/**
 	 * Marks the given message as permanent, i.e. not temporary.
 	 */

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

@@ -1040,6 +1040,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		}
 	}
 
+	@Override
+	public void setHandshakePublicKey(Transaction transaction, ContactId c, PublicKey handshakePublicKey) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		db.setHandshakePublicKey(txn, c, handshakePublicKey);
+	}
+
 	@Override
 	public void setHandshakeKeyPair(Transaction transaction, AuthorId local,
 			PublicKey publicKey, PrivateKey privateKey) throws DbException {

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

@@ -3058,6 +3058,23 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void setHandshakePublicKey(Connection txn, ContactId c, PublicKey handshakePublicKey) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE contacts SET handshakePublicKey = ? WHERE contactId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, handshakePublicKey.getEncoded());
+			ps.setInt(2, c.getInt());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setGroupVisibility(Connection txn, ContactId c, GroupId g,
 			boolean shared) throws DbException {

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

@@ -118,6 +118,11 @@ class IdentityManagerImpl implements IdentityManager, OpenDatabaseHook {
 		return cached.getLocalAuthor();
 	}
 
+	@Override
+	public Identity getIdentity(Transaction txn) throws DbException {
+		return getCachedIdentity(txn);
+	}
+
 	@Override
 	public LocalAuthor getLocalAuthor(Transaction txn) throws DbException {
 		return getCachedIdentity(txn).getLocalAuthor();

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

@@ -127,6 +127,7 @@ class KeyAgreementConnector {
 		List<Pair<DuplexPlugin, BdfList>> transports = new ArrayList<>();
 		for (TransportId id : PREFERRED_TRANSPORTS) {
 			TransportDescriptor d = descriptors.get(id);
+			LOG.info("id: " + id + " d: " + d);
 			Plugin p = pluginManager.getPlugin(id);
 			if (d != null && p instanceof DuplexPlugin) {
 				if (LOG.isLoggable(INFO))
@@ -137,6 +138,9 @@ class KeyAgreementConnector {
 
 		// TODO: If we don't have any transports in common with the peer,
 		//  warn the user and give up (#1224)
+        if (transports.isEmpty()) {
+           LOG.info("No transports found");
+        }
 
 		if (!transports.isEmpty()) {
 			byte[] commitment = remotePayload.getCommitment();

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

@@ -34,12 +34,12 @@ class KeyAgreementTransport {
 			Logger.getLogger(KeyAgreementTransport.class.getName());
 
 	// Accept records with current protocol version, known record type
-	private static Predicate<Record> ACCEPT = r ->
+	private static final Predicate<Record> ACCEPT = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					isKnownRecordType(r.getRecordType());
 
 	// Ignore records with current protocol version, unknown record type
-	private static Predicate<Record> IGNORE = r ->
+	private static final Predicate<Record> IGNORE = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					!isKnownRecordType(r.getRecordType());
 

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

@@ -294,7 +294,13 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException {
 		return db.transactionWithResult(true, txn ->
-				getRemoteProperties(txn, db.getContact(txn, c), t));
+				getRemoteProperties(txn, c, t));
+	}
+
+	@Override
+	public TransportProperties getRemoteProperties(Transaction txn,
+			ContactId c, TransportId t) throws DbException {
+		return getRemoteProperties(txn, db.getContact(txn, c), t);
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/transport/KeyManagerImpl.java

@@ -101,9 +101,9 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 	}
 
 	@Override
-	public Map<TransportId, KeySetId> addRotationKeys(
-			Transaction txn, ContactId c, SecretKey rootKey, long timestamp,
-			boolean alice, boolean active) throws DbException {
+	public Map<TransportId, KeySetId> addRotationKeys(Transaction txn,
+			ContactId c, SecretKey rootKey, long timestamp, boolean alice,
+			boolean active) throws DbException {
 		Map<TransportId, KeySetId> ids = new HashMap<>();
 		for (Entry<TransportId, TransportKeyManager> e : managers.entrySet()) {
 			TransportId t = e.getKey();
@@ -114,6 +114,14 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 		return ids;
 	}
 
+	@Override
+	public Map<TransportId, KeySetId> addRotationKeys(ContactId c,
+			SecretKey rootKey, long timestamp, boolean alice, boolean active)
+			throws DbException {
+		return db.transactionWithResult(false, txn ->
+				addRotationKeys(txn, c, rootKey, timestamp, alice, active));
+	}
+
 	@Override
 	public Map<TransportId, KeySetId> addContact(Transaction txn, ContactId c,
 			PublicKey theirPublicKey, KeyPair ourKeyPair)
@@ -137,7 +145,7 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 			PendingContactId p, PublicKey theirPublicKey, KeyPair ourKeyPair)
 			throws DbException, GeneralSecurityException {
 		SecretKey staticMasterKey = transportCrypto
-					.deriveStaticMasterKey(theirPublicKey, ourKeyPair);
+				.deriveStaticMasterKey(theirPublicKey, ourKeyPair);
 		SecretKey rootKey =
 				transportCrypto.deriveHandshakeRootKey(staticMasterKey, true);
 		boolean alice = transportCrypto.isAlice(theirPublicKey, ourKeyPair);

bramble-core/src/main/resources/bridges

@@ -1,8 +1,8 @@
 Bridge obfs4 192.95.36.142:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ iat-mode=1
 Bridge obfs4 38.229.1.78:80 C8CBDB2464FC9804A69531437BCF2BE31FDD2EE4 cert=Hmyfd2ev46gGY7NoVxA9ngrPF2zCZtzskRTzoWXbxNkzeVnGFPWmrTtILRyqCTjHR+s9dg iat-mode=1
-Bridge obfs4 38.229.33.83:80 0BAC39417268B96B9F514E7F63FA6FBA1A788955 cert=VwEFpk9F/UN9JED7XpG1XOjm/O8ZCXK80oPecgWnNDZDv5pdkhq1OpbAH0wNqOT6H6BmRQ iat-mode=1
 Bridge obfs4 37.218.245.14:38224 D9A82D2F9C2F65A18407B1D2B764F130847F8B5D cert=bjRaMrr1BRiAW8IE9U5z27fQaYgOhX1UCmOpg2pFpoMvo6ZgQMzLsaTzzQNTlm7hNcb+Sg iat-mode=0
-Bridge obfs4 85.31.186.26:443 91A6354697E6B02A386312F68D82CF86824D3606 cert=PBwr+S8JTVZo6MPdHnkTwXJPILWADLqfMGoVvhZClMq/Urndyd42BwX9YFJHZnBB3H0XCw iat-mode=0
+Bridge obfs4 85.31.186.98:443 011F2599C0E9B27EE74B353155E244813763C3E5 cert=ayq0XzCwhpdysn5o0EyDUbmSOx3X/oTEbzDMvczHOdBJKlvIdHHLJGkZARtT4dcBFArPPg iat-mode=0
+Bridge obfs4 144.217.20.138:80 FB70B257C162BF1038CA669D568D76F5B7F0BABB cert=vYIV5MgrghGQvZPIi1tJwnzorMgqgmlKaB77Y3Z9Q/v94wZBOAXkW+fdx4aSxLVnKO+xNw iat-mode=0
 Bridge obfs4 193.11.166.194:27015 2D82C2E354D531A68469ADF7F878FA6060C6BACA cert=4TLQPJrTSaDffMK7Nbao6LC7G9OW/NHkUwIdjLSS3KYf0Nv4/nQiiI8dY2TcsQx01NniOg iat-mode=0
 Bridge obfs4 193.11.166.194:27020 86AC7B8D430DAC4117E9F42C9EAED18133863AAF cert=0LDeJH4JzMDtkJJrFphJCiPqKx7loozKN7VNfuukMGfHO0Z8OGdzHVkhVAOfo1mUdv9cMg iat-mode=0
 Bridge obfs4 193.11.166.194:27025 1AE2C08904527FEA90C4C4F8C1083EA59FBC6FAF cert=ItvYZzW5tn6v3G4UnQa6Qz04Npro6e81AP70YujmK/KXwDFPTs3aHXcHp4n8Vt6w/bv8cA iat-mode=0

bramble-core/src/test/java/org/briarproject/bramble/crypto/StreamDecrypterImplTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestUtils;

bramble-core/src/test/java/org/briarproject/bramble/crypto/StreamEncrypterImplTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestUtils;

bramble-core/src/test/java/org/briarproject/bramble/crypto/TestAuthenticatedCipher.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 

bramble-core/src/test/java/org/briarproject/bramble/crypto/XSalsa20Poly1305AuthenticatedCipherTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.util.StringUtils;

briar-android/build.gradle

@@ -26,9 +26,9 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10220
-		versionName "1.2.20"
-		applicationId "org.briarproject.briar.android"
+		versionCode 10218
+		versionName "1.2.18"
+		applicationId "org.briarproject.briar.socialbackup"
 
 		vectorDrawables.useSupportLibrary = true
 		buildConfigField "String", "GitHash",
@@ -106,6 +106,7 @@ dependencies {
 	implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
 	implementation 'com.google.android.material:material:1.2.1'
 	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc03'
+	implementation 'org.magmacollective.darkcrystal:dark-crystal-secret-sharing-wrapper:1.1.0'
 
 	implementation 'info.guardianproject.panic:panic:1.0'
 	implementation 'info.guardianproject.trustedintents:trustedintents:0.2'

briar-android/proguard-rules.txt

@@ -40,3 +40,5 @@
 
 # Dependency injection annotations, needed for UI tests on older API levels
 -keep class javax.inject.**
+
+-keep class com.sun.jna.** { *; }

briar-android/src/androidTest/java/org/briarproject/briar/android/UiTest.java

@@ -4,20 +4,16 @@ import android.app.Activity;
 import android.content.Intent;
 
 import org.briarproject.bramble.api.account.AccountManager;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.briar.R;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.test.espresso.intent.rule.IntentsTestRule;
 
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
-import static org.briarproject.briar.android.controller.BriarControllerImpl.DOZE_ASK_AGAIN;
-import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 
 
 @SuppressWarnings("WeakerAccess")
@@ -31,8 +27,6 @@ public abstract class UiTest {
 	protected AccountManager accountManager;
 	@Inject
 	protected LifecycleManager lifecycleManager;
-	@Inject
-	protected SettingsManager settingsManager;
 
 	public UiTest() {
 		BriarTestComponentApplication app = getApplicationContext();
@@ -45,8 +39,22 @@ public abstract class UiTest {
 	protected class CleanAccountTestRule<A extends Activity>
 			extends IntentsTestRule<A> {
 
+		@Nullable
+		private final Runnable runnable;
+
 		public CleanAccountTestRule(Class<A> activityClass) {
 			super(activityClass);
+			this.runnable = null;
+		}
+
+		/**
+		 * Use this if you need to run code before launching the activity.
+		 * Note: You need to use {@link #launchActivity(Intent)} yourself
+		 * to start the activity.
+		 */
+		public CleanAccountTestRule(Class<A> activityClass, Runnable runnable) {
+			super(activityClass, false, false);
+			this.runnable = runnable;
 		}
 
 		@Override
@@ -54,17 +62,16 @@ public abstract class UiTest {
 			super.beforeActivityLaunched();
 			accountManager.deleteAccount();
 			accountManager.createAccount(USERNAME, PASSWORD);
-			Intent serviceIntent =
-					new Intent(getApplicationContext(), BriarService.class);
-			getApplicationContext().startService(serviceIntent);
-			try {
-				lifecycleManager.waitForStartup();
-				// do not show doze white-listing dialog
-				Settings settings = new Settings();
-				settings.putBoolean(DOZE_ASK_AGAIN, false);
-				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
-			} catch (InterruptedException | DbException e) {
-				throw new AssertionError(e);
+			if (runnable != null) {
+				Intent serviceIntent =
+						new Intent(getApplicationContext(), BriarService.class);
+				getApplicationContext().startService(serviceIntent);
+				try {
+					lifecycleManager.waitForStartup();
+				} catch (InterruptedException e) {
+					throw new AssertionError(e);
+				}
+				runnable.run();
 			}
 		}
 	}

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageCompressorTest.java

@@ -10,15 +10,12 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Logger;
 
-import androidx.test.filters.LargeTest;
-
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeTrue;
 
-@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageCompressorTest
 		extends AbstractImageCompressorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageSizeCalculatorTest.java

@@ -12,14 +12,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.logging.Logger;
 
-import androidx.test.filters.LargeTest;
-
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assume.assumeTrue;
 
-@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageSizeCalculatorTest
 		extends AbstractImageSizeCalculatorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/ConversationActivityNotSignedInTest.java

@@ -0,0 +1,39 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.Context;
+import android.content.Intent;
+
+import org.briarproject.briar.R;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.rule.ActivityTestRule;
+
+import static androidx.test.espresso.Espresso.onView;
+import static androidx.test.espresso.matcher.ViewMatchers.isDisplayed;
+import static androidx.test.espresso.matcher.ViewMatchers.withText;
+import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentation;
+import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+
+@RunWith(AndroidJUnit4.class)
+public class ConversationActivityNotSignedInTest {
+
+	@Rule
+	public ActivityTestRule<ConversationActivity> testRule =
+			new ActivityTestRule<>(ConversationActivity.class, false, false);
+
+	@Test
+	public void openWithoutSignedIn() {
+		Context targetContext = getInstrumentation().getTargetContext();
+		Intent intent = new Intent(targetContext, ConversationActivity.class);
+		intent.putExtra(CONTACT_ID, 1);
+		testRule.launchActivity(intent);
+
+		onView(withText(R.string.sign_in_button))
+				.perform(waitUntilMatches(isDisplayed()));
+	}
+
+}

briar-android/src/androidTestScreenshot/java/org/briarproject/briar/android/settings/SettingsActivityScreenshotTest.java

@@ -16,7 +16,6 @@ import androidx.test.espresso.contrib.DrawerActions;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.rule.ActivityTestRule;
 
-import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static androidx.test.espresso.Espresso.onView;
 import static androidx.test.espresso.action.ViewActions.click;
 import static androidx.test.espresso.assertion.ViewAssertions.matches;
@@ -30,9 +29,7 @@ import static androidx.test.espresso.matcher.ViewMatchers.withClassName;
 import static androidx.test.espresso.matcher.ViewMatchers.withId;
 import static androidx.test.espresso.matcher.ViewMatchers.withText;
 import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
-import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
 import static org.hamcrest.CoreMatchers.is;
-import static org.junit.Assume.assumeTrue;
 
 @RunWith(AndroidJUnit4.class)
 public class SettingsActivityScreenshotTest extends ScreenshotTest {
@@ -79,8 +76,6 @@ public class SettingsActivityScreenshotTest extends ScreenshotTest {
 
 	@Test
 	public void appLock() {
-		assumeTrue("device has no screen lock",
-				hasScreenLock(getApplicationContext()));
 		// scroll down
 		onView(withClassName(is(RecyclerView.class.getName())))
 				.perform(scrollTo(hasDescendant(

briar-android/src/debug/res/values/strings.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-	<string name="app_name" translatable="false">Briar Debug</string>
-	<string name="app_package" translatable="false">org.briarproject.briar.android.debug</string>
+	<string name="app_name" translatable="false">Briar SB Debug</string>
+	<string name="app_package" translatable="false">org.briarproject.briar.socialbackup.debug</string>
 </resources>

briar-android/src/main/AndroidManifest.xml

@@ -138,6 +138,51 @@
 			</intent-filter>
 		</activity>
 
+		<activity
+			android:name="org.briarproject.briar.android.account.NewOrRecoverActivity"
+			android:label="@string/activity_name_new_or_recover_account"
+			android:parentActivityName="org.briarproject.briar.android.login.StartupActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.login.StartupActivity" />
+		</activity>
+
+		<activity
+			android:name="org.briarproject.briar.android.socialbackup.DistributedBackupActivity"
+			android:label="@string/activity_name_distributed_backup"
+			android:parentActivityName="org.briarproject.briar.android.settings.SettingsActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.settings.SettingsActivity" />
+		</activity>
+
+		<activity
+			android:name="org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardActivity"
+			android:label="@string/activity_name_custodian_help_recovery"
+			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.conversation.ConversationActivity" />
+		</activity>
+
+		<activity
+			android:name="org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardActivity"
+			android:label="@string/activity_name_recovery"
+			android:parentActivityName="org.briarproject.briar.android.account.NewOrRecoverActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.account.NewOrRecoverActivity" />
+		</activity>
+
+		<activity
+			android:name="org.briarproject.briar.android.socialbackup.recover.RestoreAccountActivity"
+			android:label="@string/activity_name_restore_account"
+			android:parentActivityName="org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardActivity" />
+		</activity>
+
 		<activity
 			android:name="org.briarproject.briar.android.conversation.ConversationActivity"
 			android:label="@string/app_name"
@@ -342,7 +387,7 @@
 		</activity>
 
 		<activity
-			android:name="org.briarproject.briar.android.keyagreement.ContactExchangeActivity"
+			android:name="org.briarproject.briar.android.contact.add.nearby.AddNearbyContactActivity"
 			android:label="@string/add_contact_title"
 			android:parentActivityName="org.briarproject.briar.android.navdrawer.NavDrawerActivity"
 			android:theme="@style/BriarTheme.NoActionBar">

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -8,11 +8,13 @@ import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
 import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
+import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.EventBus;
@@ -59,6 +61,7 @@ import org.briarproject.briar.api.privategroup.PrivateGroupFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationFactory;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
+import org.briarproject.briar.api.socialbackup.SocialBackupManager;
 import org.briarproject.briar.api.test.TestDataCreator;
 
 import java.util.concurrent.Executor;
@@ -184,6 +187,12 @@ public interface AndroidComponent
 
 	Thread.UncaughtExceptionHandler exceptionHandler();
 
+	SocialBackupManager socialBackupManager();
+
+    DatabaseComponent databaseComponent();
+
+    ClientHelper clientHelper();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -30,11 +30,10 @@ import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.DozeHelperModule;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.account.SetupModule;
-import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactModule;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
-import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
@@ -43,6 +42,8 @@ import org.briarproject.briar.android.privategroup.list.GroupListModule;
 import org.briarproject.briar.android.reporting.DevReportModule;
 import org.briarproject.briar.android.settings.SettingsModule;
 import org.briarproject.briar.android.sharing.SharingModule;
+import org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardModule;
+import org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardModule;
 import org.briarproject.briar.android.test.TestAvatarCreatorImpl;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -50,6 +51,7 @@ import org.briarproject.briar.api.android.DozeWatchdog;
 import org.briarproject.briar.api.android.LockManager;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
 import org.briarproject.briar.api.test.TestAvatarCreator;
+import org.briarproject.briar.socialbackup.AndroidDarkCrystalModule;
 
 import java.io.File;
 import java.security.GeneralSecurityException;
@@ -76,7 +78,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 @Module(includes = {
 		SetupModule.class,
 		DozeHelperModule.class,
-		ContactExchangeModule.class,
+		AddNearbyContactModule.class,
 		LoggingModule.class,
 		LoginModule.class,
 		NavDrawerModule.class,
@@ -84,13 +86,15 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		SettingsModule.class,
 		DevReportModule.class,
 		ContactListModule.class,
+		AndroidDarkCrystalModule.class,
 		IntroductionModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
-		BlogModule.class,
 		ForumModule.class,
 		GroupListModule.class,
 		GroupConversationModule.class,
 		SharingModule.class,
+		OwnerReturnShardModule.class,
+		CustodianReturnShardModule.class
 })
 public class AppModule {
 

briar-android/src/main/java/org/briarproject/briar/android/account/DozeHelper.java

@@ -2,7 +2,7 @@ package org.briarproject.briar.android.account;
 
 import android.content.Context;
 
-interface DozeHelper {
+public interface DozeHelper {
 
 	boolean needToShowDozeFragment(Context context);
 }

briar-android/src/main/java/org/briarproject/briar/android/account/DozeView.java

@@ -14,7 +14,7 @@ import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
 
 @UiThread
 @NotNullByDefault
-class DozeView extends PowerView {
+public class DozeView extends PowerView {
 
 	@Nullable
 	private Runnable onButtonClickListener;

briar-android/src/main/java/org/briarproject/briar/android/account/HuaweiView.java

@@ -21,7 +21,7 @@ import static android.os.Build.VERSION.SDK_INT;
 
 @UiThread
 @NotNullByDefault
-class HuaweiView extends PowerView {
+public class HuaweiView extends PowerView {
 
 	private final static String PACKAGE_NAME = "com.huawei.systemmanager";
 	private final static String CLASS_NAME =

briar-android/src/main/java/org/briarproject/briar/android/account/NewOrRecoverActivity.java

@@ -0,0 +1,60 @@
+package org.briarproject.briar.android.account;
+
+import android.content.Intent;
+import android.os.Bundle;
+
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardActivity;
+
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
+import static android.content.Intent.FLAG_ACTIVITY_TASK_ON_HOME;
+
+public class NewOrRecoverActivity extends BaseActivity implements
+		BaseFragment.BaseFragmentListener, SetupNewAccountChosenListener,
+		RecoverAccountListener {
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onCreate(Bundle state) {
+		super.onCreate(state);
+		// fade-in after splash screen instead of default animation
+		// TODO the fade in is not working
+		overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
+		setContentView(R.layout.activity_fragment_container);
+		NewOrRecoverFragment fragment = NewOrRecoverFragment.newInstance();
+		showInitialFragment(fragment);
+	}
+
+	@Override
+	public void setupNewAccountChosen() {
+		finish();
+		Intent i = new Intent(this, SetupActivity.class);
+		i.addFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP |
+				FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_TASK_ON_HOME);
+		startActivity(i);
+	}
+
+	@Override
+	public void recoverAccountChosen() {
+		finish();
+		Intent i = new Intent(this, OwnerReturnShardActivity.class);
+		i.addFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP |
+				FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_TASK_ON_HOME);
+		startActivity(i);
+	}
+
+	@Override
+	@Deprecated
+	public void runOnDbThread(Runnable runnable) {
+		throw new RuntimeException("Don't use this deprecated method here.");
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/account/NewOrRecoverFragment.java

@@ -0,0 +1,70 @@
+package org.briarproject.briar.android.account;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.fragment.BaseFragment;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+public class NewOrRecoverFragment extends BaseFragment {
+
+	public static final String TAG = NewOrRecoverFragment.class.getName();
+
+	protected SetupNewAccountChosenListener setupNewAccountListener;
+	protected RecoverAccountListener recoverAccountListener;
+
+	public static NewOrRecoverFragment newInstance() {
+		Bundle bundle = new Bundle();
+		NewOrRecoverFragment fragment = new NewOrRecoverFragment();
+		fragment.setArguments(bundle);
+		return fragment;
+	}
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		requireActivity().setTitle(R.string.setup_title);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(@NonNull LayoutInflater inflater, @Nullable
+			ViewGroup container, @Nullable Bundle savedInstanceState) {
+		View view = inflater.inflate(R.layout.fragment_new_or_recover,
+				container, false);
+		Button newAccountButton = view.findViewById(R.id.buttonSetupNewAccount);
+		newAccountButton.setOnClickListener(e -> {
+			setupNewAccountListener.setupNewAccountChosen();
+		});
+
+		Button recoverAccountButton = view.findViewById(R.id.buttonRestoreAccount);
+		recoverAccountButton.setOnClickListener(e -> {
+			recoverAccountListener.recoverAccountChosen();
+		});
+		return view;
+	}
+
+	@Override
+	public void onAttach(Context context) {
+		super.onAttach(context);
+		setupNewAccountListener = (SetupNewAccountChosenListener) context;
+		recoverAccountListener = (RecoverAccountListener) context;
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/account/PowerView.java

@@ -24,7 +24,7 @@ import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
 @UiThread
 @NotNullByDefault
-abstract class PowerView extends ConstraintLayout {
+public abstract class PowerView extends ConstraintLayout {
 
 	private final TextView textView;
 	private final ImageView checkImage;
@@ -156,7 +156,7 @@ abstract class PowerView extends ConstraintLayout {
 		};
 	}
 
-	interface OnCheckedChangedListener {
+	public interface OnCheckedChangedListener {
 		void onCheckedChanged();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/account/RecoverAccountListener.java

@@ -0,0 +1,8 @@
+package org.briarproject.briar.android.account;
+
+import androidx.annotation.UiThread;
+
+public interface RecoverAccountListener {
+	@UiThread
+	void recoverAccountChosen();
+}

briar-android/src/main/java/org/briarproject/briar/android/account/SetupNewAccountChosenListener.java

@@ -0,0 +1,8 @@
+package org.briarproject.briar.android.account;
+
+import androidx.annotation.UiThread;
+
+public interface SetupNewAccountChosenListener {
+	@UiThread
+	void setupNewAccountChosen();
+}

briar-android/src/main/java/org/briarproject/briar/android/account/SetupViewModel.java

@@ -29,6 +29,7 @@ import static org.briarproject.briar.android.account.SetupViewModel.State.SET_PA
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
+public
 class SetupViewModel extends AndroidViewModel {
 	enum State {AUTHOR_NAME, SET_PASSWORD, DOZE, CREATED, FAILED}
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -2,23 +2,32 @@ package org.briarproject.briar.android.activity;
 
 import android.app.Activity;
 
+import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.briar.android.AndroidComponent;
 import org.briarproject.briar.android.StartupFailureActivity;
 import org.briarproject.briar.android.account.AuthorNameFragment;
 import org.briarproject.briar.android.account.DozeFragment;
+import org.briarproject.briar.android.account.NewOrRecoverActivity;
+import org.briarproject.briar.android.account.NewOrRecoverFragment;
 import org.briarproject.briar.android.account.SetPasswordFragment;
 import org.briarproject.briar.android.account.SetupActivity;
 import org.briarproject.briar.android.account.UnlockActivity;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.blog.BlogFragment;
+import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.blog.BlogPostFragment;
 import org.briarproject.briar.android.blog.FeedFragment;
+import org.briarproject.briar.android.blog.FeedPostFragment;
 import org.briarproject.briar.android.blog.ReblogActivity;
 import org.briarproject.briar.android.blog.ReblogFragment;
 import org.briarproject.briar.android.blog.RssFeedImportActivity;
 import org.briarproject.briar.android.blog.RssFeedManageActivity;
 import org.briarproject.briar.android.blog.WriteBlogPostActivity;
 import org.briarproject.briar.android.contact.ContactListFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactActivity;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactErrorFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactIntroFragment;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.LinkExchangeFragment;
 import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
@@ -34,10 +43,6 @@ import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.introduction.IntroductionMessageFragment;
-import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
-import org.briarproject.briar.android.keyagreement.ContactExchangeErrorFragment;
-import org.briarproject.briar.android.keyagreement.KeyAgreementActivity;
-import org.briarproject.briar.android.keyagreement.KeyAgreementFragment;
 import org.briarproject.briar.android.login.ChangePasswordActivity;
 import org.briarproject.briar.android.login.OpenDatabaseFragment;
 import org.briarproject.briar.android.login.PasswordFragment;
@@ -75,19 +80,42 @@ import org.briarproject.briar.android.sharing.ShareBlogFragment;
 import org.briarproject.briar.android.sharing.ShareForumActivity;
 import org.briarproject.briar.android.sharing.ShareForumFragment;
 import org.briarproject.briar.android.sharing.SharingModule;
+import org.briarproject.briar.android.socialbackup.recover.CustodianRecoveryModeExplainerFragment;
+import org.briarproject.briar.android.socialbackup.CustodianSelectorFragment;
+import org.briarproject.briar.android.socialbackup.DistributedBackupActivity;
+import org.briarproject.briar.android.socialbackup.ExistingBackupFragment;
+import org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardActivity;
+import org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardErrorFragment;
+import org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardFragment;
+import org.briarproject.briar.android.socialbackup.recover.CustodianReturnShardSuccessFragment;
+import org.briarproject.briar.android.socialbackup.recover.OwnerRecoveryModeErrorFragment;
+import org.briarproject.briar.android.socialbackup.recover.OwnerRecoveryModeExplainerFragment;
+import org.briarproject.briar.android.socialbackup.recover.OwnerRecoveryModeMainFragment;
+import org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardActivity;
+import org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardFragment;
+import org.briarproject.briar.android.socialbackup.ShardsSentFragment;
+import org.briarproject.briar.android.socialbackup.ThresholdSelectorFragment;
+import org.briarproject.briar.android.socialbackup.creation.CreateBackupModule;
+import org.briarproject.briar.android.socialbackup.recover.OwnerReturnShardSuccessFragment;
+import org.briarproject.briar.android.socialbackup.recover.RestoreAccountActivity;
+import org.briarproject.briar.android.socialbackup.recover.RestoreAccountDozeFragment;
+import org.briarproject.briar.android.socialbackup.recover.RestoreAccountSetPasswordFragment;
 import org.briarproject.briar.android.splash.SplashScreenActivity;
 import org.briarproject.briar.android.test.TestDataActivity;
+import org.briarproject.briar.api.socialbackup.recovery.RestoreAccount;
 
 import dagger.Component;
 
 @ActivityScope
-@Component(modules = {
+@Component(modules ={
 		ActivityModule.class,
+		BlogModule.class,
 		CreateGroupModule.class,
 		GroupInvitationModule.class,
 		GroupMemberModule.class,
 		GroupRevealModule.class,
-		SharingModule.SharingLegacyModule.class
+		SharingModule.SharingLegacyModule.class,
+		CreateBackupModule.class
 }, dependencies = AndroidComponent.class)
 public interface ActivityComponent {
 
@@ -105,9 +133,7 @@ public interface ActivityComponent {
 
 	void inject(PanicPreferencesActivity activity);
 
-	void inject(ContactExchangeActivity activity);
-
-	void inject(KeyAgreementActivity activity);
+	void inject(AddNearbyContactActivity activity);
 
 	void inject(ConversationActivity activity);
 
@@ -149,6 +175,8 @@ public interface ActivityComponent {
 
 	void inject(BlogPostFragment fragment);
 
+	void inject(FeedPostFragment fragment);
+
 	void inject(ReblogFragment fragment);
 
 	void inject(ReblogActivity activity);
@@ -177,6 +205,16 @@ public interface ActivityComponent {
 
 	void inject(CrashReportActivity crashReportActivity);
 
+	void inject(NewOrRecoverActivity newOrRecoverActivity);
+
+	void inject(CustodianReturnShardActivity custodianReturnShardActivity);
+
+    void inject(OwnerReturnShardActivity ownerReturnShardActivity);
+
+    void inject(OwnerRecoveryModeMainFragment ownerRecoveryModeMainFragment);
+
+    void inject(RestoreAccountActivity restoreAccountActivity);
+
 	// Fragments
 
 	void inject(AuthorNameFragment fragment);
@@ -203,7 +241,9 @@ public interface ActivityComponent {
 
 	void inject(FeedFragment fragment);
 
-	void inject(KeyAgreementFragment fragment);
+	void inject(AddNearbyContactIntroFragment fragment);
+
+	void inject(AddNearbyContactFragment fragment);
 
 	void inject(LinkExchangeFragment fragment);
 
@@ -221,7 +261,7 @@ public interface ActivityComponent {
 
 	void inject(ScreenFilterDialogFragment fragment);
 
-	void inject(ContactExchangeErrorFragment fragment);
+	void inject(AddNearbyContactErrorFragment fragment);
 
 	void inject(AliasDialogFragment aliasDialogFragment);
 
@@ -233,4 +273,37 @@ public interface ActivityComponent {
 
 	void inject(ConfirmAvatarDialogFragment fragment);
 
+	void inject(ThresholdSelectorFragment thresholdSelectorFragment);
+
+	void inject(DistributedBackupActivity distributedBackupActivity);
+
+	void inject(DatabaseComponent databaseComponent);
+
+	void inject(CustodianSelectorFragment custodianSelectorFragment);
+
+	void inject(ShardsSentFragment shardsSentFragment);
+
+	void inject(OwnerRecoveryModeExplainerFragment ownerRecoveryModeExplainerFragment);
+
+	void inject(ExistingBackupFragment existingBackupFragment);
+
+	void inject(NewOrRecoverFragment newOrRecoverFragment);
+
+	void inject(CustodianRecoveryModeExplainerFragment custodianRecoveryModeExplainerFragment);
+
+	void inject(CustodianReturnShardFragment custodianReturnShardFragment);
+
+	void inject(OwnerReturnShardFragment ownerReturnShardFragment);
+
+	void inject(CustodianReturnShardSuccessFragment custodianReturnShardSuccessFragment);
+
+	void inject(RestoreAccountSetPasswordFragment restoreAccountSetPasswordFragment);
+
+	void inject(RestoreAccountDozeFragment restoreAccountDozeFragment);
+
+	void inject(OwnerReturnShardSuccessFragment ownerReturnShardSuccessFragment);
+
+	void inject(OwnerRecoveryModeErrorFragment ownerRecoveryModeErrorFragment);
+
+	void inject(CustodianReturnShardErrorFragment custodianReturnShardErrorFragment);
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java

@@ -6,11 +6,10 @@ public interface RequestCodes {
 	int REQUEST_INTRODUCTION = 2;
 	int REQUEST_GROUP_INVITE = 3;
 	int REQUEST_SHARE_FORUM = 4;
+	int REQUEST_WRITE_BLOG_POST = 5;
 	int REQUEST_SHARE_BLOG = 6;
 	int REQUEST_RINGTONE = 7;
-	int REQUEST_PERMISSION_CAMERA_LOCATION = 8;
 	int REQUEST_DOZE_WHITELISTING = 9;
-	int REQUEST_BLUETOOTH_DISCOVERABLE = 10;
 	int REQUEST_UNLOCK = 11;
 	int REQUEST_KEYGUARD_UNLOCK = 12;
 	int REQUEST_ATTACH_IMAGE = 13;

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseController.java

@@ -0,0 +1,48 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.handler.ExceptionHandler;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+interface BaseController {
+
+	@UiThread
+	void onStart();
+
+	@UiThread
+	void onStop();
+
+	void loadBlogPosts(GroupId g,
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadBlogPost(BlogPostHeader header,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void loadBlogPost(GroupId g, MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void repeatPost(BlogPostItem item, @Nullable String comment,
+			ExceptionHandler<DbException> handler);
+
+	@NotNullByDefault
+	interface BlogListener {
+
+		@UiThread
+		void onBlogPostAdded(BlogPostHeader header, boolean local);
+
+		@UiThread
+		void onBlogRemoved();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseControllerImpl.java

@@ -0,0 +1,209 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.DbControllerImpl;
+import org.briarproject.briar.android.controller.handler.ExceptionHandler;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogCommentHeader;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.util.HtmlUtils;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.CallSuper;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+abstract class BaseControllerImpl extends DbControllerImpl
+		implements BaseController, EventListener {
+
+	private static final Logger LOG =
+			Logger.getLogger(BaseControllerImpl.class.getName());
+
+	protected final EventBus eventBus;
+	protected final AndroidNotificationManager notificationManager;
+	protected final IdentityManager identityManager;
+	protected final BlogManager blogManager;
+
+	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private final Map<MessageId, BlogPostHeader> headerCache =
+			new ConcurrentHashMap<>();
+
+	BaseControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			AndroidNotificationManager notificationManager,
+			IdentityManager identityManager, BlogManager blogManager) {
+		super(dbExecutor, lifecycleManager);
+		this.eventBus = eventBus;
+		this.notificationManager = notificationManager;
+		this.identityManager = identityManager;
+		this.blogManager = blogManager;
+	}
+
+	@Override
+	@CallSuper
+	public void onStart() {
+		eventBus.addListener(this);
+	}
+
+	@Override
+	@CallSuper
+	public void onStop() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void loadBlogPosts(GroupId groupId,
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				Collection<BlogPostItem> items = loadItems(groupId);
+				handler.onResult(items);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	Collection<BlogPostItem> loadItems(GroupId groupId) throws DbException {
+		long start = now();
+		Collection<BlogPostHeader> headers =
+				blogManager.getPostHeaders(groupId);
+		logDuration(LOG, "Loading headers", start);
+		Collection<BlogPostItem> items = new ArrayList<>(headers.size());
+		start = now();
+		for (BlogPostHeader h : headers) {
+			headerCache.put(h.getId(), h);
+			BlogPostItem item = getItem(h);
+			items.add(item);
+		}
+		logDuration(LOG, "Loading bodies", start);
+		return items;
+	}
+
+	@Override
+	public void loadBlogPost(BlogPostHeader header,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+
+		String text = textCache.get(header.getId());
+		if (text != null) {
+			LOG.info("Loaded text from cache");
+			handler.onResult(new BlogPostItem(header, text));
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				BlogPostItem item = getItem(header);
+				logDuration(LOG, "Loading text", start);
+				handler.onResult(item);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void loadBlogPost(GroupId g, MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+
+		BlogPostHeader header = headerCache.get(m);
+		if (header != null) {
+			LOG.info("Loaded header from cache");
+			loadBlogPost(header, handler);
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				BlogPostHeader header1 = getPostHeader(g, m);
+				BlogPostItem item = getItem(header1);
+				logDuration(LOG, "Loading post", start);
+				handler.onResult(item);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void repeatPost(BlogPostItem item, @Nullable String comment,
+			ExceptionHandler<DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				BlogPostHeader h = item.getHeader();
+				blogManager.addLocalComment(a, b.getId(), comment, h);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	private BlogPostHeader getPostHeader(GroupId g, MessageId m)
+			throws DbException {
+		BlogPostHeader header = headerCache.get(m);
+		if (header == null) {
+			header = blogManager.getPostHeader(g, m);
+			headerCache.put(m, header);
+		}
+		return header;
+	}
+
+	@DatabaseExecutor
+	private BlogPostItem getItem(BlogPostHeader h) throws DbException {
+		String text;
+		if (h instanceof BlogCommentHeader) {
+			BlogCommentHeader c = (BlogCommentHeader) h;
+			BlogCommentItem item = new BlogCommentItem(c);
+			text = getPostText(item.getPostHeader().getId());
+			item.setText(text);
+			return item;
+		} else {
+			text = getPostText(h.getId());
+			return new BlogPostItem(h, text);
+		}
+	}
+
+	@DatabaseExecutor
+	private String getPostText(MessageId m) throws DbException {
+		String text = textCache.get(m);
+		if (text == null) {
+			text = HtmlUtils.clean(blogManager.getPostText(m), ARTICLE);
+			textCache.put(m, text);
+		}
+		return text;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -0,0 +1,121 @@
+package org.briarproject.briar.android.blog;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ProgressBar;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.fragment.BaseFragment;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.CallSuper;
+import androidx.annotation.UiThread;
+
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
+
+@UiThread
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+abstract class BasePostFragment extends BaseFragment {
+
+	static final String POST_ID = "briar.POST_ID";
+
+	private static final Logger LOG =
+			getLogger(BasePostFragment.class.getName());
+
+	private final Handler handler = new Handler(Looper.getMainLooper());
+
+	protected MessageId postId;
+	private ProgressBar progressBar;
+	private BlogPostViewHolder ui;
+	private BlogPostItem post;
+	private Runnable refresher;
+
+	@CallSuper
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		// retrieve MessageId of blog post from arguments
+		byte[] p = requireArguments().getByteArray(POST_ID);
+		if (p == null) throw new IllegalStateException("No post ID in args");
+		postId = new MessageId(p);
+
+		View view = inflater.inflate(R.layout.fragment_blog_post, container,
+				false);
+		progressBar = view.findViewById(R.id.progressBar);
+		progressBar.setVisibility(VISIBLE);
+		ui = new BlogPostViewHolder(view, true, new OnBlogPostClickListener() {
+			@Override
+			public void onBlogPostClick(BlogPostItem post) {
+				// We're already there
+			}
+
+			@Override
+			public void onAuthorClick(BlogPostItem post) {
+				if (getContext() == null) return;
+				Intent i = new Intent(getContext(), BlogActivity.class);
+				i.putExtra(GROUP_ID, post.getGroupId().getBytes());
+				i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+				getContext().startActivity(i);
+			}
+		}, getFragmentManager());
+		return view;
+	}
+
+	@CallSuper
+	@Override
+	public void onStart() {
+		super.onStart();
+		startPeriodicUpdate();
+	}
+
+	@CallSuper
+	@Override
+	public void onStop() {
+		super.onStop();
+		stopPeriodicUpdate();
+	}
+
+	@UiThread
+	protected void onBlogPostLoaded(BlogPostItem post) {
+		progressBar.setVisibility(INVISIBLE);
+		this.post = post;
+		ui.bindItem(post);
+	}
+
+	private void startPeriodicUpdate() {
+		refresher = () -> {
+			LOG.info("Updating Content...");
+			ui.updateDate(post.getTimestamp());
+			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+		};
+		LOG.info("Adding Handler Callback");
+		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+	}
+
+	private void stopPeriodicUpdate() {
+		if (refresher != null) {
+			LOG.info("Removing Handler Callback");
+			handler.removeCallbacks(refresher);
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseViewModel.java

@@ -1,216 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.DbViewModel;
-import org.briarproject.briar.android.viewmodel.LiveResult;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogCommentHeader;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-import org.briarproject.briar.util.HtmlUtils;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.UiThread;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
-
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
-
-@NotNullByDefault
-abstract class BaseViewModel extends DbViewModel implements EventListener {
-
-	private static final Logger LOG = getLogger(BaseViewModel.class.getName());
-
-	private final EventBus eventBus;
-	protected final IdentityManager identityManager;
-	protected final AndroidNotificationManager notificationManager;
-	protected final BlogManager blogManager;
-
-	protected final MutableLiveData<LiveResult<ListUpdate>> blogPosts =
-			new MutableLiveData<>();
-
-	BaseViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
-			AndroidNotificationManager notificationManager,
-			BlogManager blogManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.eventBus = eventBus;
-		this.identityManager = identityManager;
-		this.notificationManager = notificationManager;
-		this.blogManager = blogManager;
-		eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
-	}
-
-	@DatabaseExecutor
-	protected List<BlogPostItem> loadBlogPosts(Transaction txn, GroupId groupId)
-			throws DbException {
-		long start = now();
-		List<BlogPostHeader> headers =
-				blogManager.getPostHeaders(txn, groupId);
-		logDuration(LOG, "Loading headers", start);
-		List<BlogPostItem> items = new ArrayList<>(headers.size());
-		start = now();
-		for (BlogPostHeader h : headers) {
-			BlogPostItem item = getItem(txn, h);
-			items.add(item);
-		}
-		logDuration(LOG, "Loading bodies", start);
-		return items;
-	}
-
-	@DatabaseExecutor
-	protected BlogPostItem getItem(Transaction txn, BlogPostHeader h)
-			throws DbException {
-		String text;
-		if (h instanceof BlogCommentHeader) {
-			BlogCommentHeader c = (BlogCommentHeader) h;
-			BlogCommentItem item = new BlogCommentItem(c);
-			text = getPostText(txn, item.getPostHeader().getId());
-			item.setText(text);
-			return item;
-		} else {
-			text = getPostText(txn, h.getId());
-			return new BlogPostItem(h, text);
-		}
-	}
-
-	@DatabaseExecutor
-	private String getPostText(Transaction txn, MessageId m)
-			throws DbException {
-		return HtmlUtils.clean(blogManager.getPostText(txn, m), ARTICLE);
-	}
-
-	LiveData<LiveResult<BlogPostItem>> loadBlogPost(GroupId g, MessageId m) {
-		MutableLiveData<LiveResult<BlogPostItem>> result =
-				new MutableLiveData<>();
-		runOnDbThread(true, txn -> {
-			long start = now();
-			BlogPostHeader header = blogManager.getPostHeader(txn, g, m);
-			BlogPostItem item = getItem(txn, header);
-			logDuration(LOG, "Loading post", start);
-			result.postValue(new LiveResult<>(item));
-		}, e -> {
-			logException(LOG, WARNING, e);
-			result.postValue(new LiveResult<>(e));
-		});
-		return result;
-	}
-
-	protected void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		runOnDbThread(true, txn -> {
-			BlogPostItem item = getItem(txn, header);
-			txn.attach(() -> onBlogPostItemAdded(item, local));
-		}, this::handleException);
-	}
-
-	@UiThread
-	private void onBlogPostItemAdded(BlogPostItem item, boolean local) {
-		List<BlogPostItem> items = addListItem(getBlogPostItems(), item);
-		if (items != null) {
-			Collections.sort(items);
-			blogPosts.setValue(new LiveResult<>(new ListUpdate(local, items)));
-		}
-	}
-
-	void repeatPost(BlogPostItem item, @Nullable String comment) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				BlogPostHeader h = item.getHeader();
-				blogManager.addLocalComment(a, b.getId(), comment, h);
-			} catch (DbException e) {
-				handleException(e);
-			}
-		});
-	}
-
-	LiveData<LiveResult<ListUpdate>> getBlogPosts() {
-		return blogPosts;
-	}
-
-	@UiThread
-	@Nullable
-	protected List<BlogPostItem> getBlogPostItems() {
-		LiveResult<ListUpdate> value = blogPosts.getValue();
-		if (value == null) return null;
-		ListUpdate result = value.getResultOrNull();
-		return result == null ? null : result.getItems();
-	}
-
-	/**
-	 * Call this after {@link ListUpdate#getPostAddedWasLocal()} was processed.
-	 * This prevents it from getting processed again.
-	 */
-	@UiThread
-	void resetLocalUpdate() {
-		LiveResult<ListUpdate> value = blogPosts.getValue();
-		if (value == null) return;
-		ListUpdate result = value.getResultOrNull();
-		result.postAddedWasLocal = null;
-	}
-
-	static class ListUpdate {
-
-		@Nullable
-		private Boolean postAddedWasLocal;
-		private final List<BlogPostItem> items;
-
-		ListUpdate(@Nullable Boolean postAddedWasLocal,
-				List<BlogPostItem> items) {
-			this.postAddedWasLocal = postAddedWasLocal;
-			this.items = items;
-		}
-
-		/**
-		 * @return null when not a single post was added with this update.
-		 * true when a single post was added locally and false if remotely.
-		 */
-		@Nullable
-		public Boolean getPostAddedWasLocal() {
-			return postAddedWasLocal;
-		}
-
-		public List<BlogPostItem> getItems() {
-			return items;
-		}
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogActivity.java

@@ -6,11 +6,9 @@ import android.os.Bundle;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 import org.briarproject.briar.android.sharing.BlogSharingStatusActivity;
 
@@ -18,10 +16,6 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.widget.Toolbar;
-import androidx.lifecycle.ViewModelProvider;
-
-import static java.util.Objects.requireNonNull;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -29,16 +23,7 @@ public class BlogActivity extends BriarActivity
 		implements BaseFragmentListener {
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private BlogViewModel viewModel;
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
-		viewModel = new ViewModelProvider(this, viewModelFactory)
-				.get(BlogViewModel.class);
-	}
+	BlogController blogController;
 
 	@Override
 	public void onCreate(@Nullable Bundle state) {
@@ -46,46 +31,32 @@ public class BlogActivity extends BriarActivity
 
 		// GroupId from Intent
 		Intent i = getIntent();
-		GroupId groupId =
-				new GroupId(requireNonNull(i.getByteArrayExtra(GROUP_ID)));
-		// Get post info from intent
-		@Nullable byte[] postId = i.getByteArrayExtra(POST_ID);
-
-		viewModel.setGroupId(groupId, postId == null);
+		byte[] b = i.getByteArrayExtra(GROUP_ID);
+		if (b == null) throw new IllegalStateException("No group ID in intent");
+		GroupId groupId = new GroupId(b);
+		blogController.setGroupId(groupId);
 
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = setUpCustomToolbar(false);
 
 		// Open Sharing Status on Toolbar click
-		toolbar.setOnClickListener(v -> {
-			Intent i1 = new Intent(BlogActivity.this,
-					BlogSharingStatusActivity.class);
-			i1.putExtra(GROUP_ID, groupId.getBytes());
-			startActivity(i1);
-		});
-
-		viewModel.getBlog().observe(this, blog ->
-				setTitle(blog.getBlog().getAuthor().getName())
-		);
-		viewModel.getSharingInfo().observe(this, info ->
-				setToolbarSubTitle(info.total, info.online)
-		);
+		if (toolbar != null) {
+			toolbar.setOnClickListener(v -> {
+				Intent i1 = new Intent(BlogActivity.this,
+						BlogSharingStatusActivity.class);
+				i1.putExtra(GROUP_ID, groupId.getBytes());
+				startActivity(i1);
+			});
+		}
 
 		if (state == null) {
-			if (postId == null) {
-				showInitialFragment(BlogFragment.newInstance(groupId));
-			} else {
-				MessageId messageId = new MessageId(postId);
-				BaseFragment f =
-						BlogPostFragment.newInstance(groupId, messageId);
-				showInitialFragment(f);
-			}
+			showInitialFragment(BlogFragment.newInstance(groupId));
 		}
 	}
 
-	private void setToolbarSubTitle(int total, int online) {
-		requireNonNull(getSupportActionBar())
-				.setSubtitle(getString(R.string.shared_with, total, online));
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogCommentItem.java

@@ -8,9 +8,7 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
-import javax.annotation.concurrent.NotThreadSafe;
-
-@NotThreadSafe
+// This class is not thread-safe
 class BlogCommentItem extends BlogPostItem {
 
 	private static final BlogCommentComparator COMPARATOR =

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogController.java

@@ -0,0 +1,46 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+public interface BlogController extends BaseController {
+
+	void setGroupId(GroupId g);
+
+	@UiThread
+	void setBlogSharingListener(BlogSharingListener listener);
+
+	@UiThread
+	void unsetBlogSharingListener(BlogSharingListener listener);
+
+	void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadBlogPost(MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void loadBlog(ResultExceptionHandler<BlogItem, DbException> handler);
+
+	void deleteBlog(ResultExceptionHandler<Void, DbException> handler);
+
+	void loadSharingContacts(
+			ResultExceptionHandler<Collection<ContactId>, DbException> handler);
+
+	interface BlogSharingListener extends BlogListener {
+		@UiThread
+		void onBlogInvitationAccepted(ContactId c);
+
+		@UiThread
+		void onBlogLeft(ContactId c);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogControllerImpl.java

@@ -1,24 +1,24 @@
 package org.briarproject.briar.android.blog;
 
-import android.app.Application;
+import android.app.Activity;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.sharing.SharingController;
-import org.briarproject.briar.android.sharing.SharingController.SharingInfo;
+import org.briarproject.briar.android.controller.ActivityLifecycleController;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.Blog;
 import org.briarproject.briar.api.blog.BlogInvitationResponse;
@@ -35,54 +35,85 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.annotation.UiThread;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
+import androidx.annotation.Nullable;
 
-import static java.util.logging.Logger.getLogger;
+import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogViewModel extends BaseViewModel {
+class BlogControllerImpl extends BaseControllerImpl
+		implements ActivityLifecycleController, BlogController, EventListener {
 
-	private static final Logger LOG = getLogger(BlogViewModel.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(BlogControllerImpl.class.getName());
 
 	private final BlogSharingManager blogSharingManager;
-	private final SharingController sharingController;
 
-	private volatile GroupId groupId;
+	// UI thread
+	@Nullable
+	private BlogSharingListener listener;
 
-	private final MutableLiveData<BlogItem> blog = new MutableLiveData<>();
-	private final MutableLiveData<Boolean> blogRemoved =
-			new MutableLiveData<>();
+	private volatile GroupId groupId = null;
 
 	@Inject
-	BlogViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
+	BlogControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
 			AndroidNotificationManager notificationManager,
-			BlogManager blogManager,
-			BlogSharingManager blogSharingManager,
-			SharingController sharingController) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
-				eventBus, identityManager, notificationManager, blogManager);
+			IdentityManager identityManager, BlogManager blogManager,
+			BlogSharingManager blogSharingManager) {
+		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
+				identityManager, blogManager);
 		this.blogSharingManager = blogSharingManager;
-		this.sharingController = sharingController;
+	}
+
+	@Override
+	public void onActivityCreate(Activity activity) {
+	}
+
+	@Override
+	public void onActivityStart() {
+		super.onStart();
+		notificationManager.blockNotification(groupId);
+		notificationManager.clearBlogPostNotification(groupId);
+	}
+
+	@Override
+	public void onActivityStop() {
+		super.onStop();
+		notificationManager.unblockNotification(groupId);
+	}
+
+	@Override
+	public void onActivityDestroy() {
+	}
+
+	@Override
+	public void setGroupId(GroupId g) {
+		groupId = g;
+	}
+
+	@Override
+	public void setBlogSharingListener(BlogSharingListener listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void unsetBlogSharingListener(BlogSharingListener listener) {
+		if (this.listener == listener) this.listener = null;
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
+		if (groupId == null || listener == null)
+			throw new IllegalStateException();
 		if (e instanceof BlogPostAddedEvent) {
 			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
 			if (b.getGroupId().equals(groupId)) {
 				LOG.info("Blog post added");
-				onBlogPostAdded(b.getHeader(), b.isLocal());
+				listener.onBlogPostAdded(b.getHeader(), b.isLocal());
 			}
 		} else if (e instanceof BlogInvitationResponseReceivedEvent) {
 			BlogInvitationResponseReceivedEvent b =
@@ -90,36 +121,41 @@ class BlogViewModel extends BaseViewModel {
 			BlogInvitationResponse r = b.getMessageHeader();
 			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
 				LOG.info("Blog invitation accepted");
-				sharingController.add(b.getContactId());
+				listener.onBlogInvitationAccepted(b.getContactId());
 			}
 		} else if (e instanceof ContactLeftShareableEvent) {
 			ContactLeftShareableEvent s = (ContactLeftShareableEvent) e;
 			if (s.getGroupId().equals(groupId)) {
 				LOG.info("Blog left by contact");
-				sharingController.remove(s.getContactId());
+				listener.onBlogLeft(s.getContactId());
 			}
 		} else if (e instanceof GroupRemovedEvent) {
 			GroupRemovedEvent g = (GroupRemovedEvent) e;
 			if (g.getGroup().getId().equals(groupId)) {
 				LOG.info("Blog removed");
-				blogRemoved.setValue(true);
+				listener.onBlogRemoved();
 			}
 		}
 	}
 
-	/**
-	 * Set this before calling any other methods.
-	 */
-	@UiThread
-	public void setGroupId(GroupId groupId, boolean loadAllPosts) {
-		if (this.groupId == groupId) return; // configuration change
-		this.groupId = groupId;
-		loadBlog(groupId);
-		if (loadAllPosts) loadBlogPosts(groupId);
-		loadSharingContacts(groupId);
+	@Override
+	public void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
+		loadBlogPosts(groupId, handler);
 	}
 
-	private void loadBlog(GroupId groupId) {
+	@Override
+	public void loadBlogPost(MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
+		loadBlogPost(groupId, m, handler);
+	}
+
+	@Override
+	public void loadBlog(
+			ResultExceptionHandler<BlogItem, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
 		runOnDbThread(() -> {
 			try {
 				long start = now();
@@ -127,65 +163,50 @@ class BlogViewModel extends BaseViewModel {
 				Blog b = blogManager.getBlog(groupId);
 				boolean ours = a.getId().equals(b.getAuthor().getId());
 				boolean removable = blogManager.canBeRemoved(b);
-				blog.postValue(new BlogItem(b, ours, removable));
+				BlogItem blog = new BlogItem(b, ours, removable);
 				logDuration(LOG, "Loading blog", start);
+				handler.onResult(blog);
 			} catch (DbException e) {
-				handleException(e);
+				logException(LOG, WARNING, e);
+				handler.onException(e);
 			}
 		});
 	}
 
-	void blockAndClearNotifications() {
-		notificationManager.blockNotification(groupId);
-		notificationManager.clearBlogPostNotification(groupId);
-	}
-
-	void unblockNotifications() {
-		notificationManager.unblockNotification(groupId);
-	}
-
-	private void loadBlogPosts(GroupId groupId) {
-		loadFromDb(txn -> new ListUpdate(null, loadBlogPosts(txn, groupId)),
-				blogPosts::setValue);
-	}
-
-	private void loadSharingContacts(GroupId groupId) {
-		runOnDbThread(true, txn -> {
-			Collection<Contact> contacts =
-					blogSharingManager.getSharedWith(txn, groupId);
-			txn.attach(() -> onSharingContactsLoaded(contacts));
-		}, this::handleException);
-	}
-
-	@UiThread
-	private void onSharingContactsLoaded(Collection<Contact> contacts) {
-		Collection<ContactId> contactIds = new ArrayList<>(contacts.size());
-		for (Contact c : contacts) contactIds.add(c.getId());
-		sharingController.addAll(contactIds);
-	}
-
-	void deleteBlog() {
+	@Override
+	public void deleteBlog(ResultExceptionHandler<Void, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
 		runOnDbThread(() -> {
 			try {
 				long start = now();
 				Blog b = blogManager.getBlog(groupId);
 				blogManager.removeBlog(b);
 				logDuration(LOG, "Removing blog", start);
+				handler.onResult(null);
 			} catch (DbException e) {
-				handleException(e);
+				logException(LOG, WARNING, e);
+				handler.onException(e);
 			}
 		});
 	}
 
-	LiveData<BlogItem> getBlog() {
-		return blog;
+	@Override
+	public void loadSharingContacts(
+			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
+		runOnDbThread(() -> {
+			try {
+				Collection<Contact> contacts =
+						blogSharingManager.getSharedWith(groupId);
+				Collection<ContactId> contactIds =
+						new ArrayList<>(contacts.size());
+				for (Contact c : contacts) contactIds.add(c.getId());
+				handler.onResult(contactIds);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
 	}
 
-	LiveData<Boolean> getBlogRemoved() {
-		return blogRemoved;
-	}
-
-	LiveData<SharingInfo> getSharingInfo() {
-		return sharingController.getSharingInfo();
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -1,7 +1,9 @@
 package org.briarproject.briar.android.blog;
 
+import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -10,25 +12,33 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
 
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
+import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.blog.BlogController.BlogSharingListener;
+import org.briarproject.briar.android.controller.SharingController;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.sharing.BlogSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareBlogActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
+import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AlertDialog;
-import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView.LayoutManager;
 
@@ -38,22 +48,31 @@ import static android.widget.Toast.LENGTH_SHORT;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
+import static org.briarproject.briar.android.controller.SharingController.SharingListener;
 
 @UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class BlogFragment extends BaseFragment
-		implements OnBlogPostClickListener {
+		implements BlogSharingListener, SharingListener,
+		OnBlogPostClickListener {
 
 	private final static String TAG = BlogFragment.class.getName();
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	BlogController blogController;
+	@Inject
+	SharingController sharingController;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	private GroupId groupId;
-	private BlogViewModel viewModel;
-	private final BlogPostAdapter adapter = new BlogPostAdapter(false, this);
+	private BlogPostAdapter adapter;
+	private LayoutManager layoutManager;
 	private BriarRecyclerView list;
+	private MenuItem writeButton, deleteButton;
+	private boolean isMyBlog = false, canDeleteBlog = false;
 
 	static BlogFragment newInstance(GroupId groupId) {
 		BlogFragment f = new BlogFragment();
@@ -68,8 +87,8 @@ public class BlogFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(BlogViewModel.class);
+		blogController.setBlogSharingListener(this);
+		sharingController.setSharingListener(this);
 	}
 
 	@Nullable
@@ -84,82 +103,106 @@ public class BlogFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
+		adapter = new BlogPostAdapter(requireActivity(), this,
+				getFragmentManager());
 		list = v.findViewById(R.id.postList);
-		LayoutManager layoutManager = new LinearLayoutManager(getActivity());
+		layoutManager = new LinearLayoutManager(getActivity());
 		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.showProgressBar();
 		list.setEmptyText(getString(R.string.blogs_other_blog_empty_state));
 
-		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
-				result.onError(this::handleException)
-						.onSuccess(this::onBlogPostsLoaded)
-		);
-		viewModel.getBlogRemoved().observe(getViewLifecycleOwner(), removed -> {
-			if (removed) finish();
-		});
+		if (savedInstanceState != null) {
+			layoutManagerState =
+					savedInstanceState.getParcelable("layoutManager");
+		}
+
 		return v;
 	}
 
 	@Override
 	public void onStart() {
 		super.onStart();
-		viewModel.blockAndClearNotifications();
+		sharingController.onStart();
+		loadBlog();
+		loadSharedContacts();
+		loadBlogPosts(false);
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		viewModel.unblockNotifications();
+		sharingController.onStop();
 		list.stopPeriodicUpdate();
 	}
 
+	@Override
+	public void onDestroy() {
+		super.onDestroy();
+		blogController.unsetBlogSharingListener(this);
+		sharingController.unsetSharingListener(this);
+	}
+
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.blogs_blog_actions, menu);
-		MenuItem writeButton = menu.findItem(R.id.action_write_blog_post);
-		MenuItem deleteButton = menu.findItem(R.id.action_blog_delete);
-		viewModel.getBlog().observe(getViewLifecycleOwner(), blog -> {
-			if (blog.isOurs()) writeButton.setVisible(true);
-			if (blog.canBeRemoved()) deleteButton.setEnabled(true);
-		});
+		writeButton = menu.findItem(R.id.action_write_blog_post);
+		if (isMyBlog) writeButton.setVisible(true);
+		deleteButton = menu.findItem(R.id.action_blog_delete);
+		if (canDeleteBlog) deleteButton.setEnabled(true);
+
 		super.onCreateOptionsMenu(menu, inflater);
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		int itemId = item.getItemId();
-		if (itemId == R.id.action_write_blog_post) {
-			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
-			i.putExtra(GROUP_ID, groupId.getBytes());
-			startActivity(i);
-			return true;
-		} else if (itemId == R.id.action_blog_share) {
-			Intent i = new Intent(getActivity(), ShareBlogActivity.class);
-			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-			i.putExtra(GROUP_ID, groupId.getBytes());
-			startActivityForResult(i, REQUEST_SHARE_BLOG);
-			return true;
-		} else if (itemId == R.id.action_blog_sharing_status) {
-			Intent i =
-					new Intent(getActivity(), BlogSharingStatusActivity.class);
-			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-			i.putExtra(GROUP_ID, groupId.getBytes());
-			startActivity(i);
-			return true;
-		} else if (itemId == R.id.action_blog_delete) {
-			showDeleteDialog();
-			return true;
+		switch (item.getItemId()) {
+			case R.id.action_write_blog_post:
+				Intent i = new Intent(getActivity(),
+						WriteBlogPostActivity.class);
+				i.putExtra(GROUP_ID, groupId.getBytes());
+				startActivityForResult(i, REQUEST_WRITE_BLOG_POST);
+				return true;
+			case R.id.action_blog_share:
+				Intent i2 = new Intent(getActivity(), ShareBlogActivity.class);
+				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+				i2.putExtra(GROUP_ID, groupId.getBytes());
+				startActivityForResult(i2, REQUEST_SHARE_BLOG);
+				return true;
+			case R.id.action_blog_sharing_status:
+				Intent i3 = new Intent(getActivity(),
+						BlogSharingStatusActivity.class);
+				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+				i3.putExtra(GROUP_ID, groupId.getBytes());
+				startActivity(i3);
+				return true;
+			case R.id.action_blog_delete:
+				showDeleteDialog();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
 	public void onActivityResult(int request, int result,
 			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
-		if (request == REQUEST_SHARE_BLOG && result == RESULT_OK) {
+
+		if (request == REQUEST_WRITE_BLOG_POST && result == RESULT_OK) {
+			displaySnackbar(R.string.blogs_blog_post_created, true);
+			loadBlogPosts(true);
+		} else if (request == REQUEST_SHARE_BLOG && result == RESULT_OK) {
 			displaySnackbar(R.string.blogs_sharing_snackbar, false);
 		}
 	}
@@ -169,26 +212,35 @@ public class BlogFragment extends BaseFragment
 		return TAG;
 	}
 
-	private void onBlogPostsLoaded(ListUpdate update) {
-		adapter.submitList(update.getItems(), () -> {
-			Boolean wasLocal = update.getPostAddedWasLocal();
-			if (wasLocal != null && wasLocal) {
-				list.scrollToPosition(0);
-				displaySnackbar(R.string.blogs_blog_post_created,
-						false);
-			} else if (wasLocal != null) {
-				displaySnackbar(R.string.blogs_blog_post_received,
-						true);
-			}
-			viewModel.resetLocalUpdate();
-			list.showData();
-		});
+	@Override
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		blogController.loadBlogPost(header,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						adapter.add(post);
+						if (local) {
+							list.scrollToPosition(0);
+							displaySnackbar(R.string.blogs_blog_post_created,
+									false);
+						} else {
+							displaySnackbar(R.string.blogs_blog_post_received,
+									true);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				}
+		);
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		BlogPostFragment f =
-				BlogPostFragment.newInstance(groupId, post.getId());
+		BlogPostFragment f = BlogPostFragment.newInstance(post.getId());
 		showNextFragment(f);
 	}
 
@@ -204,10 +256,111 @@ public class BlogFragment extends BaseFragment
 		getContext().startActivity(i);
 	}
 
+	private void loadBlogPosts(boolean reload) {
+		blogController.loadBlogPosts(
+				new UiResultExceptionHandler<Collection<BlogPostItem>,
+						DbException>(this) {
+					@Override
+					public void onResultUi(Collection<BlogPostItem> posts) {
+						if (posts.isEmpty()) {
+							list.showData();
+						} else {
+							adapter.addAll(posts);
+							if (reload || layoutManagerState == null) {
+								list.scrollToPosition(0);
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void loadBlog() {
+		blogController.loadBlog(
+				new UiResultExceptionHandler<BlogItem, DbException>(this) {
+					@Override
+					public void onResultUi(BlogItem blog) {
+						setToolbarTitle(blog.getBlog().getAuthor());
+						if (blog.isOurs())
+							showWriteButton();
+						if (blog.canBeRemoved())
+							enableDeleteButton();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void setToolbarTitle(Author a) {
+		getActivity().setTitle(a.getName());
+	}
+
+	private void loadSharedContacts() {
+		blogController.loadSharingContacts(
+				new UiResultExceptionHandler<Collection<ContactId>,
+						DbException>(this) {
+					@Override
+					public void onResultUi(Collection<ContactId> contacts) {
+						sharingController.addAll(contacts);
+						int online = sharingController.getOnlineCount();
+						setToolbarSubTitle(contacts.size(), online);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
 	@Override
-	public void onLinkClick(String url) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
+	public void onBlogInvitationAccepted(ContactId c) {
+		sharingController.add(c);
+		setToolbarSubTitle(sharingController.getTotalCount(),
+				sharingController.getOnlineCount());
+	}
+
+	@Override
+	public void onBlogLeft(ContactId c) {
+		sharingController.remove(c);
+		setToolbarSubTitle(sharingController.getTotalCount(),
+				sharingController.getOnlineCount());
+	}
+
+	@Override
+	public void onSharingInfoUpdated(int total, int online) {
+		setToolbarSubTitle(total, online);
+	}
+
+	private void setToolbarSubTitle(int total, int online) {
+		ActionBar actionBar =
+				((BriarActivity) getActivity()).getSupportActionBar();
+		if (actionBar != null) {
+			actionBar.setSubtitle(
+					getString(R.string.shared_with, total, online));
+		}
+	}
+
+	private void showWriteButton() {
+		isMyBlog = true;
+		if (writeButton != null)
+			writeButton.setVisible(true);
+	}
+
+	private void enableDeleteButton() {
+		canDeleteBlog = true;
+		if (deleteButton != null)
+			deleteButton.setEnabled(true);
 	}
 
 	private void displaySnackbar(int stringId, boolean scroll) {
@@ -220,21 +373,38 @@ public class BlogFragment extends BaseFragment
 	}
 
 	private void showDeleteDialog() {
-		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
+		DialogInterface.OnClickListener okListener =
+				(dialog, which) -> deleteBlog();
+		AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.blogs_remove_blog));
 		builder.setMessage(
 				getString(R.string.blogs_remove_blog_dialog_message));
 		builder.setPositiveButton(R.string.cancel, null);
-		builder.setNegativeButton(R.string.blogs_remove_blog_ok,
-				(dialog, which) -> deleteBlog());
+		builder.setNegativeButton(R.string.blogs_remove_blog_ok, okListener);
 		builder.show();
 	}
 
 	private void deleteBlog() {
-		viewModel.deleteBlog();
-		Toast.makeText(getActivity(), R.string.blogs_blog_removed, LENGTH_SHORT)
-				.show();
+		blogController.deleteBlog(
+				new UiResultExceptionHandler<Void, DbException>(this) {
+					@Override
+					public void onResultUi(Void result) {
+						Toast.makeText(getActivity(),
+								R.string.blogs_blog_removed, LENGTH_SHORT)
+								.show();
+						finish();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	@Override
+	public void onBlogRemoved() {
 		finish();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogModule.java

@@ -1,23 +1,35 @@
 package org.briarproject.briar.android.blog;
 
-import org.briarproject.briar.android.viewmodel.ViewModelKey;
+import org.briarproject.briar.android.activity.ActivityScope;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.controller.SharingController;
+import org.briarproject.briar.android.controller.SharingControllerImpl;
 
-import androidx.lifecycle.ViewModel;
-import dagger.Binds;
 import dagger.Module;
-import dagger.multibindings.IntoMap;
+import dagger.Provides;
 
 @Module
-public interface BlogModule {
+public class BlogModule {
 
-	@Binds
-	@IntoMap
-	@ViewModelKey(FeedViewModel.class)
-	ViewModel bindFeedViewModel(FeedViewModel feedViewModel);
+	@ActivityScope
+	@Provides
+	BlogController provideBlogController(BaseActivity activity,
+			BlogControllerImpl blogController) {
+		activity.addLifecycleController(blogController);
+		return blogController;
+	}
 
-	@Binds
-	@IntoMap
-	@ViewModelKey(BlogViewModel.class)
-	ViewModel bindBlogViewModel(BlogViewModel blogViewModel);
+	@ActivityScope
+	@Provides
+	FeedController provideFeedController(FeedControllerImpl feedController) {
+		return feedController;
+	}
+
+	@ActivityScope
+	@Provides
+	SharingController provideSharingController(
+			SharingControllerImpl sharingController) {
+		return sharingController;
+	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostAdapter.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.blog;
 
+import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -7,44 +8,52 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.BriarAdapter;
 
-import androidx.recyclerview.widget.DiffUtil;
-import androidx.recyclerview.widget.ListAdapter;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.FragmentManager;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogPostAdapter extends ListAdapter<BlogPostItem, BlogPostViewHolder> {
+class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
 
-	private final boolean authorClickable;
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
-	BlogPostAdapter(boolean authorClickable, OnBlogPostClickListener listener) {
-		super(new DiffUtil.ItemCallback<BlogPostItem>() {
-			@Override
-			public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
-				return a.getId().equals(b.getId());
-			}
-
-			@Override
-			public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
-				return a.isRead() == b.isRead();
-			}
-		});
-		this.authorClickable = authorClickable;
+	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener,
+			@Nullable FragmentManager fragmentManager) {
+		super(ctx, BlogPostItem.class);
 		this.listener = listener;
+		this.fragmentManager = fragmentManager;
 	}
 
 	@Override
 	public BlogPostViewHolder onCreateViewHolder(ViewGroup parent,
 			int viewType) {
-		View v = LayoutInflater.from(parent.getContext()).inflate(
+		View v = LayoutInflater.from(ctx).inflate(
 				R.layout.list_item_blog_post, parent, false);
-		return new BlogPostViewHolder(v, false, listener, authorClickable);
+		return new BlogPostViewHolder(v, false, listener, fragmentManager);
 	}
 
 	@Override
 	public void onBindViewHolder(BlogPostViewHolder ui, int position) {
-		ui.bindItem(getItem(position));
+		ui.bindItem(getItemAt(position));
+	}
+
+	@Override
+	public int compare(BlogPostItem a, BlogPostItem b) {
+		return a.compareTo(b);
+	}
+
+	@Override
+	public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
+		return a.isRead() == b.isRead();
+	}
+
+	@Override
+	public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
+		return a.getId().equals(b.getId());
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostFragment.java

@@ -1,159 +1,76 @@
 package org.briarproject.briar.android.blog;
 
-import android.content.Intent;
 import android.os.Bundle;
-import android.os.Handler;
-import android.os.Looper;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.ProgressBar;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseFragment;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
+import org.briarproject.briar.android.blog.BaseController.BlogListener;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+import org.briarproject.briar.api.blog.BlogPostHeader;
 
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
-import androidx.lifecycle.LifecycleOwner;
-import androidx.lifecycle.ViewModelProvider;
-
-import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
-import static android.view.View.INVISIBLE;
-import static android.view.View.VISIBLE;
-import static java.util.Objects.requireNonNull;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
 
+@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class BlogPostFragment extends BaseFragment
-		implements OnBlogPostClickListener {
+public class BlogPostFragment extends BasePostFragment implements BlogListener {
 
 	private static final String TAG = BlogPostFragment.class.getName();
-	private static final Logger LOG = getLogger(TAG);
-
-	static final String POST_ID = "briar.POST_ID";
-
-	protected BlogViewModel viewModel;
-	private final Handler handler = new Handler(Looper.getMainLooper());
-
-	private ProgressBar progressBar;
-	private BlogPostViewHolder ui;
-	private BlogPostItem post;
-	private Runnable refresher;
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	BlogController blogController;
 
-	static BlogPostFragment newInstance(GroupId blogId, MessageId postId) {
+	static BlogPostFragment newInstance(MessageId postId) {
 		BlogPostFragment f = new BlogPostFragment();
+
 		Bundle bundle = new Bundle();
-		bundle.putByteArray(GROUP_ID, blogId.getBytes());
 		bundle.putByteArray(POST_ID, postId.getBytes());
+
 		f.setArguments(bundle);
 		return f;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(BlogViewModel.class);
-	}
-
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireArguments();
-		GroupId groupId =
-				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
-		MessageId postId =
-				new MessageId(requireNonNull(args.getByteArray(POST_ID)));
-
-		View view = inflater.inflate(R.layout.fragment_blog_post, container,
-				false);
-		progressBar = view.findViewById(R.id.progressBar);
-		progressBar.setVisibility(VISIBLE);
-		ui = new BlogPostViewHolder(view, true, this, false);
-		LifecycleOwner owner = getViewLifecycleOwner();
-		viewModel.loadBlogPost(groupId, postId).observe(owner, result ->
-				result.onError(this::handleException)
-						.onSuccess(this::onBlogPostLoaded)
-		);
-		return view;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		startPeriodicUpdate();
-	}
-
-	@Override
-	public void onStop() {
-		super.onStop();
-		stopPeriodicUpdate();
-	}
-
-	@UiThread
-	private void onBlogPostLoaded(BlogPostItem post) {
-		progressBar.setVisibility(INVISIBLE);
-		this.post = post;
-		ui.bindItem(post);
-	}
-
-	@Override
-	public void onBlogPostClick(BlogPostItem post) {
-		// We're already there
-	}
-
-	@Override
-	public void onAuthorClick(BlogPostItem post) {
-		Intent i = new Intent(requireContext(), BlogActivity.class);
-		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
-		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		requireContext().startActivity(i);
-	}
-
-	@Override
-	public void onLinkClick(String url) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
-	}
-
-	private void startPeriodicUpdate() {
-		refresher = () -> {
-			LOG.info("Updating Content...");
-			ui.updateDate(post.getTimestamp());
-			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-		};
-		LOG.info("Adding Handler Callback");
-		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-	}
-
-	private void stopPeriodicUpdate() {
-		if (refresher != null) {
-			LOG.info("Removing Handler Callback");
-			handler.removeCallbacks(refresher);
-		}
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		blogController.loadBlogPost(postId,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						onBlogPostLoaded(post);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	@Override
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		// doesn't matter here
+	}
+
+	@Override
+	public void onBlogRemoved() {
+		finish();
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostItem.java

@@ -17,7 +17,7 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 	private final BlogPostHeader header;
 	@Nullable
 	protected String text;
-	private final boolean read;
+	private boolean read;
 
 	BlogPostItem(BlogPostHeader header, @Nullable String text) {
 		this.header = header;
@@ -74,6 +74,9 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 
 	protected static int compare(BlogPostHeader h1, BlogPostHeader h2) {
 		// The newest post comes first
-		return Long.compare(h2.getTimeReceived(), h1.getTimeReceived());
+		long aTime = h1.getTimeReceived(), bTime = h2.getTimeReceived();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		return 0;
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostViewHolder.java

@@ -9,31 +9,31 @@ import android.view.ViewGroup;
 import android.widget.ImageButton;
 import android.widget.TextView;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.AuthorView;
 import org.briarproject.briar.api.blog.BlogCommentHeader;
 import org.briarproject.briar.api.blog.BlogPostHeader;
 
+import javax.annotation.Nullable;
+
+import androidx.annotation.NonNull;
 import androidx.annotation.UiThread;
 import androidx.core.view.ViewCompat;
+import androidx.fragment.app.FragmentManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 import static org.briarproject.briar.android.util.UiUtils.TEASER_LENGTH;
 import static org.briarproject.briar.android.util.UiUtils.getSpanned;
 import static org.briarproject.briar.android.util.UiUtils.getTeaser;
 import static org.briarproject.briar.android.util.UiUtils.makeLinksClickable;
-import static org.briarproject.briar.android.view.AuthorView.COMMENTER;
-import static org.briarproject.briar.android.view.AuthorView.REBLOGGER;
-import static org.briarproject.briar.android.view.AuthorView.RSS_FEED_REBLOGGED;
+import static org.briarproject.briar.api.blog.MessageType.POST;
 
 @UiThread
-@NotNullByDefault
 class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 	private final Context ctx;
@@ -43,16 +43,20 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 	private final ImageButton reblogButton;
 	private final TextView text;
 	private final ViewGroup commentContainer;
-	private final boolean fullText, authorClickable;
+	private final boolean fullText;
 
+	@NonNull
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
 	BlogPostViewHolder(View v, boolean fullText,
-			OnBlogPostClickListener listener, boolean authorClickable) {
+			@NonNull OnBlogPostClickListener listener,
+			@Nullable FragmentManager fragmentManager) {
 		super(v);
 		this.fullText = fullText;
 		this.listener = listener;
-		this.authorClickable = authorClickable;
+		this.fragmentManager = fragmentManager;
 
 		ctx = v.getContext();
 		layout = v.findViewById(R.id.postLayout);
@@ -63,6 +67,10 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		commentContainer = v.findViewById(R.id.commentContainer);
 	}
 
+	void setVisibility(int visibility) {
+		layout.setVisibility(visibility);
+	}
+
 	void hideReblogButton() {
 		reblogButton.setVisibility(GONE);
 	}
@@ -79,15 +87,15 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		return "blogPost" + id.hashCode();
 	}
 
-	void bindItem(BlogPostItem item) {
+	void bindItem(@Nullable BlogPostItem item) {
+		if (item == null) return;
+
 		setTransitionName(item.getId());
 		if (!fullText) {
 			layout.setClickable(true);
 			layout.setOnClickListener(v -> listener.onBlogPostClick(item));
 		}
 
-		boolean isReblog = item instanceof BlogCommentItem;
-
 		// author and date
 		BlogPostHeader post = item.getPostHeader();
 		author.setAuthor(post.getAuthor(), post.getAuthorInfo());
@@ -95,7 +103,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		author.setPersona(
 				item.isRssFeed() ? AuthorView.RSS_FEED : AuthorView.NORMAL);
 		// TODO make author clickable more often #624
-		if (authorClickable && !isReblog) {
+		if (!fullText && item.getHeader().getType() == POST) {
 			author.setAuthorClickable(v -> listener.onAuthorClick(item));
 		} else {
 			author.setAuthorNotClickable();
@@ -106,7 +114,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		if (fullText) {
 			text.setText(postText);
 			text.setTextIsSelectable(true);
-			makeLinksClickable(text, listener::onLinkClick);
+			makeLinksClickable(text, fragmentManager);
 		} else {
 			text.setTextIsSelectable(false);
 			if (postText.length() > TEASER_LENGTH)
@@ -124,33 +132,32 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 		// comments
 		commentContainer.removeAllViews();
-		if (isReblog) {
-			onBindComment((BlogCommentItem) item, authorClickable);
+		if (item instanceof BlogCommentItem) {
+			onBindComment((BlogCommentItem) item);
 		} else {
 			reblogger.setVisibility(GONE);
 		}
 	}
 
-	private void onBindComment(BlogCommentItem item, boolean authorClickable) {
+	private void onBindComment(BlogCommentItem item) {
 		// reblogger
 		reblogger.setAuthor(item.getAuthor(), item.getAuthorInfo());
 		reblogger.setDate(item.getTimestamp());
-		if (authorClickable) {
+		if (!fullText) {
 			reblogger.setAuthorClickable(v -> listener.onAuthorClick(item));
-		} else {
-			reblogger.setAuthorNotClickable();
 		}
 		reblogger.setVisibility(VISIBLE);
-		reblogger.setPersona(REBLOGGER);
+		reblogger.setPersona(AuthorView.REBLOGGER);
 
 		author.setPersona(item.getHeader().getRootPost().isRssFeed() ?
-				RSS_FEED_REBLOGGED : COMMENTER);
+				AuthorView.RSS_FEED_REBLOGGED :
+				AuthorView.COMMENTER);
 
 		// comments
-		// TODO use nested RecyclerView instead like we do for Image Attachments
 		for (BlogCommentHeader c : item.getComments()) {
-			View v = LayoutInflater.from(ctx).inflate(
-					R.layout.list_item_blog_comment, commentContainer, false);
+			View v = LayoutInflater.from(ctx)
+					.inflate(R.layout.list_item_blog_comment,
+							commentContainer, false);
 
 			AuthorView author = v.findViewById(R.id.authorView);
 			TextView text = v.findViewById(R.id.textView);

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedController.java

@@ -0,0 +1,32 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.blog.Blog;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+public interface FeedController extends BaseController {
+
+	void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
+
+	@UiThread
+	void setFeedListener(FeedListener listener);
+
+	@UiThread
+	void unsetFeedListener(FeedListener listener);
+
+	@NotNullByDefault
+	interface FeedListener extends BlogListener {
+
+		@UiThread
+		void onBlogAdded();
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedControllerImpl.java

@@ -0,0 +1,143 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchGroupException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class FeedControllerImpl extends BaseControllerImpl implements FeedController {
+
+	private static final Logger LOG =
+			Logger.getLogger(FeedControllerImpl.class.getName());
+
+	// UI thread
+	@Nullable
+	private FeedListener listener;
+
+	@Inject
+	FeedControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			AndroidNotificationManager notificationManager,
+			IdentityManager identityManager, BlogManager blogManager) {
+		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
+				identityManager, blogManager);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		if (listener == null) throw new IllegalStateException();
+		notificationManager.blockAllBlogPostNotifications();
+		notificationManager.clearAllBlogPostNotifications();
+	}
+
+	@Override
+	public void onStop() {
+		super.onStop();
+		notificationManager.unblockAllBlogPostNotifications();
+	}
+
+	@Override
+	public void setFeedListener(FeedListener listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void unsetFeedListener(FeedListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (listener == null) throw new IllegalStateException();
+		if (e instanceof BlogPostAddedEvent) {
+			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
+			LOG.info("Blog post added");
+			listener.onBlogPostAdded(b.getHeader(), b.isLocal());
+		} else if (e instanceof GroupAddedEvent) {
+			GroupAddedEvent g = (GroupAddedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog added");
+				listener.onBlogAdded();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog removed");
+				listener.onBlogRemoved();
+			}
+		}
+	}
+
+	@Override
+	public void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Collection<BlogPostItem> posts = new ArrayList<>();
+				for (Blog b : blogManager.getBlogs()) {
+					try {
+						posts.addAll(loadItems(b.getId()));
+					} catch (NoSuchGroupException | NoSuchMessageException e) {
+						logException(LOG, WARNING, e);
+					}
+				}
+				logDuration(LOG, "Loading all posts", start);
+				handler.onResult(posts);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void loadPersonalBlog(
+			ResultExceptionHandler<Blog, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Author a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				logDuration(LOG, "Loading personal blog", start);
+				handler.onResult(b);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -9,43 +10,53 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
+import org.briarproject.briar.android.blog.FeedController.FeedListener;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
 import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
+import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.ViewModelProvider;
+import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
+import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
+@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class FeedFragment extends BaseFragment
-		implements OnBlogPostClickListener {
+public class FeedFragment extends BaseFragment implements
+		OnBlogPostClickListener, FeedListener {
 
 	public final static String TAG = FeedFragment.class.getName();
+	private static final Logger LOG = Logger.getLogger(TAG);
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	FeedController feedController;
 
-	private FeedViewModel viewModel;
-	private final BlogPostAdapter adapter = new BlogPostAdapter(true, this);
+	private BlogPostAdapter adapter;
 	private LinearLayoutManager layoutManager;
 	private BriarRecyclerView list;
+	@Nullable
+	private Blog personalBlog;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	public static FeedFragment newInstance() {
 		FeedFragment f = new FeedFragment();
@@ -59,8 +70,7 @@ public class FeedFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(this, viewModelFactory)
-				.get(FeedViewModel.class);
+		feedController.setFeedListener(this);
 	}
 
 	@Nullable
@@ -72,6 +82,9 @@ public class FeedFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
+		adapter =
+				new BlogPostAdapter(getActivity(), this, getFragmentManager());
+
 		layoutManager = new LinearLayoutManager(getActivity());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(layoutManager);
@@ -80,39 +93,103 @@ public class FeedFragment extends BaseFragment
 		list.setEmptyText(R.string.blogs_feed_empty_state);
 		list.setEmptyAction(R.string.blogs_feed_empty_state_action);
 
-		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
-				result.onError(this::handleException)
-						.onSuccess(this::onBlogPostsLoaded)
-		);
+		if (savedInstanceState != null) {
+			layoutManagerState =
+					savedInstanceState.getParcelable("layoutManager");
+		}
 
 		return v;
 	}
 
+	@Override
+	public void onActivityResult(int requestCode, int resultCode,
+			@Nullable Intent data) {
+		super.onActivityResult(requestCode, resultCode, data);
+
+		// The BlogPostAddedEvent arrives when the controller is not listening
+		if (requestCode == REQUEST_WRITE_BLOG_POST && resultCode == RESULT_OK) {
+			showSnackBar(R.string.blogs_blog_post_created);
+		}
+	}
+
 	@Override
 	public void onStart() {
 		super.onStart();
-		viewModel.blockAndClearAllBlogPostNotifications();
+		feedController.onStart();
 		list.startPeriodicUpdate();
+		loadPersonalBlog();
+		loadBlogPosts(false);
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		viewModel.unblockAllBlogPostNotifications();
+		feedController.onStop();
+		adapter.clear();
+		list.showProgressBar();
 		list.stopPeriodicUpdate();
+		// TODO save list position in database/preferences?
 	}
 
-	private void onBlogPostsLoaded(ListUpdate update) {
-		adapter.submitList(update.getItems(), () -> {
-			Boolean wasLocal = update.getPostAddedWasLocal();
-			if (wasLocal != null && wasLocal) {
-				showSnackBar(R.string.blogs_blog_post_created);
-			} else if (wasLocal != null) {
-				showSnackBar(R.string.blogs_blog_post_received);
-			}
-			viewModel.resetLocalUpdate();
-			list.showData();
-		});
+	@Override
+	public void onDestroy() {
+		super.onDestroy();
+		feedController.unsetFeedListener(this);
+	}
+
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
+	private void loadPersonalBlog() {
+		feedController.loadPersonalBlog(
+				new UiResultExceptionHandler<Blog, DbException>(this) {
+					@Override
+					public void onResultUi(Blog b) {
+						personalBlog = b;
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void loadBlogPosts(boolean clear) {
+		int revision = adapter.getRevision();
+		feedController.loadBlogPosts(
+				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
+						this) {
+					@Override
+					public void onResultUi(Collection<BlogPostItem> posts) {
+						if (revision == adapter.getRevision()) {
+							adapter.incrementRevision();
+							if (clear) adapter.setItems(posts);
+							else adapter.addAll(posts);
+							if (posts.isEmpty()) list.showData();
+							if (layoutManagerState == null) {
+								list.scrollToPosition(0);  // Scroll to the top
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
+						} else {
+							LOG.info("Concurrent update, reloading");
+							loadBlogPosts(clear);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 	}
 
 	@Override
@@ -123,46 +200,67 @@ public class FeedFragment extends BaseFragment
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		int itemId = item.getItemId();
-		if (itemId == R.id.action_write_blog_post) {
-			Blog personalBlog = viewModel.getPersonalBlog().getValue();
-			if (personalBlog == null) return false;
-			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
-			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-			startActivity(i);
-			return true;
-		} else if (itemId == R.id.action_rss_feeds_import) {
-			Intent i = new Intent(getActivity(), RssFeedImportActivity.class);
-			startActivity(i);
-			return true;
-		} else if (itemId == R.id.action_rss_feeds_manage) {
-			Blog personalBlog = viewModel.getPersonalBlog().getValue();
-			if (personalBlog == null) return false;
-			Intent i = new Intent(getActivity(), RssFeedManageActivity.class);
-			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-			startActivity(i);
-			return true;
+		if (personalBlog == null) return false;
+		switch (item.getItemId()) {
+			case R.id.action_write_blog_post:
+				Intent i1 =
+						new Intent(getActivity(), WriteBlogPostActivity.class);
+				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+				startActivityForResult(i1, REQUEST_WRITE_BLOG_POST);
+				return true;
+			case R.id.action_rss_feeds_import:
+				Intent i2 =
+						new Intent(getActivity(), RssFeedImportActivity.class);
+				startActivity(i2);
+				return true;
+			case R.id.action_rss_feeds_manage:
+				Intent i3 =
+						new Intent(getActivity(), RssFeedManageActivity.class);
+				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+				startActivity(i3);
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
+	}
+
+	@Override
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		feedController.loadBlogPost(header,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						adapter.incrementRevision();
+						adapter.add(post);
+						if (local) {
+							showSnackBar(R.string.blogs_blog_post_created);
+						} else {
+							showSnackBar(R.string.blogs_blog_post_received);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				}
+		);
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		Intent i = getBlogActivityIntent(post.getGroupId());
-		i.putExtra(POST_ID, post.getId().getBytes());
-		requireContext().startActivity(i);
+		FeedPostFragment f =
+				FeedPostFragment.newInstance(post.getGroupId(), post.getId());
+		showNextFragment(f);
 	}
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
-		Intent i = getBlogActivityIntent(post.getGroupId());
-		requireContext().startActivity(i);
-	}
-
-	@Override
-	public void onLinkClick(String url) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
+		Intent i = new Intent(getContext(), BlogActivity.class);
+		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
+		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+		getContext().startActivity(i);
 	}
 
 	@Override
@@ -170,13 +268,6 @@ public class FeedFragment extends BaseFragment
 		return TAG;
 	}
 
-	private Intent getBlogActivityIntent(GroupId groupId) {
-		Intent i = new Intent(requireContext(), BlogActivity.class);
-		i.putExtra(GROUP_ID, groupId.getBytes());
-		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		return i;
-	}
-
 	private void showSnackBar(int stringRes) {
 		int firstVisible =
 				layoutManager.findFirstCompletelyVisibleItemPosition();
@@ -192,4 +283,14 @@ public class FeedFragment extends BaseFragment
 		sb.make(list, stringRes, LENGTH_LONG).show();
 	}
 
+	@Override
+	public void onBlogAdded() {
+		loadBlogPosts(false);
+	}
+
+	@Override
+	public void onBlogRemoved() {
+		loadBlogPosts(true);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -0,0 +1,87 @@
+package org.briarproject.briar.android.blog;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+
+@UiThread
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class FeedPostFragment extends BasePostFragment {
+
+	private static final String TAG = FeedPostFragment.class.getName();
+
+	private GroupId blogId;
+
+	@Inject
+	FeedController feedController;
+
+	static FeedPostFragment newInstance(GroupId blogId, MessageId postId) {
+		FeedPostFragment f = new FeedPostFragment();
+
+		Bundle bundle = new Bundle();
+		bundle.putByteArray(GROUP_ID, blogId.getBytes());
+		bundle.putByteArray(POST_ID, postId.getBytes());
+
+		f.setArguments(bundle);
+		return f;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		Bundle args = requireArguments();
+		byte[] b = args.getByteArray(GROUP_ID);
+		if (b == null) throw new IllegalStateException("No group ID in args");
+		blogId = new GroupId(b);
+
+		return super.onCreateView(inflater, container, savedInstanceState);
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		feedController.loadBlogPost(blogId, postId,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						onBlogPostLoaded(post);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedViewModel.java

@@ -1,133 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.LiveResult;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
-
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
-
-@NotNullByDefault
-class FeedViewModel extends BaseViewModel {
-
-	private static final Logger LOG = getLogger(FeedViewModel.class.getName());
-
-	private final MutableLiveData<Blog> personalBlog = new MutableLiveData<>();
-
-	@Inject
-	FeedViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
-			AndroidNotificationManager notificationManager,
-			BlogManager blogManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
-				eventBus, identityManager, notificationManager, blogManager);
-		loadPersonalBlog();
-		loadAllBlogPosts();
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof BlogPostAddedEvent) {
-			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
-			LOG.info("Blog post added");
-			onBlogPostAdded(b.getHeader(), b.isLocal());
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog removed");
-				onBlogRemoved(g.getGroup().getId());
-			}
-		}
-	}
-
-	void blockAndClearAllBlogPostNotifications() {
-		notificationManager.blockAllBlogPostNotifications();
-		notificationManager.clearAllBlogPostNotifications();
-	}
-
-	void unblockAllBlogPostNotifications() {
-		notificationManager.unblockAllBlogPostNotifications();
-	}
-
-	private void loadPersonalBlog() {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Author a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				logDuration(LOG, "Loading personal blog", start);
-				personalBlog.postValue(b);
-			} catch (DbException e) {
-				handleException(e);
-			}
-		});
-	}
-
-	LiveData<Blog> getPersonalBlog() {
-		return personalBlog;
-	}
-
-	private void loadAllBlogPosts() {
-		loadFromDb(this::loadAllBlogPosts, blogPosts::setValue);
-	}
-
-	@DatabaseExecutor
-	private ListUpdate loadAllBlogPosts(Transaction txn)
-			throws DbException {
-		long start = now();
-		List<BlogPostItem> posts = new ArrayList<>();
-		for (GroupId g : blogManager.getBlogIds(txn)) {
-			posts.addAll(loadBlogPosts(txn, g));
-		}
-		Collections.sort(posts);
-		logDuration(LOG, "Loading all posts", start);
-		return new ListUpdate(null, posts);
-	}
-
-	@UiThread
-	private void onBlogRemoved(GroupId g) {
-		List<BlogPostItem> items = removeListItems(getBlogPostItems(), item ->
-				item.getGroupId().equals(g)
-		);
-		if (items != null) {
-			blogPosts.setValue(new LiveResult<>(new ListUpdate(null, items)));
-		}
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/OnBlogPostClickListener.java

@@ -5,6 +5,4 @@ interface OnBlogPostClickListener {
 	void onBlogPostClick(BlogPostItem post);
 
 	void onAuthorClick(BlogPostItem post);
-
-	void onLinkClick(String url);
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogActivity.java

@@ -11,7 +11,7 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 
 public class ReblogActivity extends BriarActivity implements
 		BaseFragmentListener {
@@ -39,11 +39,13 @@ public class ReblogActivity extends BriarActivity implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == android.R.id.home) {
-			onBackPressed();
-			return true;
+		switch (item.getItemId()) {
+			case android.R.id.home:
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -7,17 +7,19 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 import android.widget.ScrollView;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
 
 import java.util.List;
@@ -25,15 +27,13 @@ import java.util.List;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.lifecycle.ViewModelProvider;
-
 import static android.view.View.FOCUS_DOWN;
 import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 import static org.briarproject.briar.api.blog.BlogConstants.MAX_BLOG_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
@@ -42,13 +42,12 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 
 	public static final String TAG = ReblogFragment.class.getName();
 
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private BlogViewModel viewModel;
 	private ViewHolder ui;
 	private BlogPostItem item;
 
+	@Inject
+	FeedController feedController;
+
 	static ReblogFragment newInstance(GroupId groupId, MessageId messageId) {
 		ReblogFragment f = new ReblogFragment();
 
@@ -68,8 +67,6 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(BlogViewModel.class);
 	}
 
 	@Override
@@ -93,20 +90,30 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setMaxTextLength(MAX_BLOG_POST_TEXT_LENGTH);
 		showProgressBar();
 
-		viewModel.loadBlogPost(blogId, postId).observe(getViewLifecycleOwner(),
-				result -> result.onError(this::handleException)
-						.onSuccess(this::bindViewHolder)
-		);
+		feedController.loadBlogPost(blogId, postId,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem result) {
+						item = result;
+						bindViewHolder();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 
 		return v;
 	}
 
-	private void bindViewHolder(BlogPostItem item) {
-		this.item = item;
+	private void bindViewHolder() {
+		if (item == null) return;
 
 		hideProgressBar();
 
-		ui.post.bindItem(this.item);
+		ui.post.bindItem(item);
 		ui.post.hideReblogButton();
 
 		ui.input.setReady(true);
@@ -117,7 +124,13 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	public void onSendClick(@Nullable String text,
 			List<AttachmentHeader> headers) {
 		ui.input.hideSoftKeyboard();
-		viewModel.repeatPost(item, text);
+		feedController.repeatPost(item, text,
+				new UiExceptionHandler<DbException>(this) {
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 		finish();
 	}
 
@@ -131,7 +144,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setVisibility(VISIBLE);
 	}
 
-	private class ViewHolder implements OnBlogPostClickListener {
+	private class ViewHolder {
 
 		private final ScrollView scrollView;
 		private final ProgressBar progressBar;
@@ -142,25 +155,18 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			scrollView = v.findViewById(R.id.scrollView);
 			progressBar = v.findViewById(R.id.progressBar);
 			post = new BlogPostViewHolder(v.findViewById(R.id.postLayout),
-					true, this, false);
+					true, new OnBlogPostClickListener() {
+				@Override
+				public void onBlogPostClick(BlogPostItem post) {
+					// do nothing
+				}
+
+				@Override
+				public void onAuthorClick(BlogPostItem post) {
+					// probably don't want to allow author clicks here
+				}
+			}, getFragmentManager());
 			input = v.findViewById(R.id.inputText);
 		}
-
-		@Override
-		public void onBlogPostClick(BlogPostItem post) {
-			// do nothing
-		}
-
-		@Override
-		public void onAuthorClick(BlogPostItem post) {
-			// probably don't want to allow author clicks here
-		}
-
-		@Override
-		public void onLinkClick(String url) {
-			LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-			f.show(getParentFragmentManager(), f.getUniqueTag());
-		}
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -15,11 +15,11 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactActivity;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.fragment.BaseFragment;
-import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 
@@ -125,7 +125,8 @@ public class ContactListFragment extends BaseFragment
 		switch (itemId) {
 			case R.id.action_add_contact_nearby:
 				Intent intent =
-						new Intent(getContext(), ContactExchangeActivity.class);
+						new Intent(getContext(),
+								AddNearbyContactActivity.class);
 				startActivity(intent);
 				return;
 			case R.id.action_add_contact_remotely:

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactsViewModel.java

@@ -86,7 +86,7 @@ public class ContactsViewModel extends DbViewModel implements EventListener {
 	}
 
 	protected void loadContacts() {
-		loadFromDb(this::loadContacts, contactListItems::setValue);
+		loadList(this::loadContacts, contactListItems::setValue);
 	}
 
 	private List<ContactListItem> loadContacts(Transaction txn)
@@ -151,7 +151,7 @@ public class ContactsViewModel extends DbViewModel implements EventListener {
 	@UiThread
 	private void updateItem(ContactId c,
 			Function<ContactListItem, ContactListItem> replacer, boolean sort) {
-		List<ContactListItem> list = updateListItems(getList(contactListItems),
+		List<ContactListItem> list = updateListItems(contactListItems,
 				itemToTest -> itemToTest.getContact().getId().equals(c),
 				replacer);
 		if (list == null) return;
@@ -161,8 +161,10 @@ public class ContactsViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void removeItem(ContactId c) {
-		removeAndUpdateListItems(contactListItems,
+		List<ContactListItem> list = removeListItems(contactListItems,
 				itemToTest -> itemToTest.getContact().getId().equals(c));
+		if (list == null) return;
+		contactListItems.setValue(new LiveResult<>(list));
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddContactState.java

@@ -0,0 +1,76 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.graphics.Bitmap;
+
+import org.briarproject.bramble.api.identity.Author;
+
+import androidx.annotation.Nullable;
+
+abstract class AddContactState {
+
+	static class KeyAgreementListening extends AddContactState {
+		final Bitmap qrCode;
+
+		KeyAgreementListening(Bitmap qrCode) {
+			this.qrCode = qrCode;
+		}
+	}
+
+	static class QrCodeScanned extends AddContactState {
+	}
+
+	static class KeyAgreementWaiting extends AddContactState {
+	}
+
+	static class KeyAgreementStarted extends AddContactState {
+	}
+
+	static class ContactExchangeStarted extends AddContactState {
+	}
+
+	static class ContactExchangeFinished extends AddContactState {
+		final ContactExchangeResult result;
+
+		ContactExchangeFinished(ContactExchangeResult result) {
+			this.result = result;
+		}
+	}
+
+	static class Failed extends AddContactState {
+		/**
+		 * Non-null if failed due to the scanned QR code version.
+		 * True if the app producing the code is too old.
+		 * False if the scanning app is too old.
+		 */
+		@Nullable
+		final Boolean qrCodeTooOld;
+
+		Failed(@Nullable Boolean qrCodeTooOld) {
+			this.qrCodeTooOld = qrCodeTooOld;
+		}
+
+		Failed() {
+			this(null);
+		}
+	}
+
+	abstract static class ContactExchangeResult {
+		static class Success extends ContactExchangeResult {
+			final Author remoteAuthor;
+
+			Success(Author remoteAuthor) {
+				this.remoteAuthor = remoteAuthor;
+			}
+		}
+
+		static class Error extends ContactExchangeResult {
+			@Nullable
+			final Author duplicateAuthor;
+
+			Error(@Nullable Author duplicateAuthor) {
+				this.duplicateAuthor = duplicateAuthor;
+			}
+		}
+	} // end ContactExchangeResult
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactActivity.java

@@ -0,0 +1,204 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeFinished;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.Failed;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
+import org.briarproject.briar.android.util.RequestBluetoothDiscoverable;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.appcompat.widget.Toolbar;
+import androidx.fragment.app.FragmentManager;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.ACCEPTED;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactActivity extends BriarActivity
+		implements BaseFragmentListener {
+
+	private static final Logger LOG =
+			getLogger(AddNearbyContactActivity.class.getName());
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private final ActivityResultLauncher<Integer> bluetoothLauncher =
+			registerForActivityResult(new RequestBluetoothDiscoverable(),
+					this::onBluetoothDiscoverableResult);
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+		setContentView(R.layout.activity_fragment_container_toolbar);
+		Toolbar toolbar = findViewById(R.id.toolbar);
+		setSupportActionBar(toolbar);
+		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
+		if (state == null) {
+			showInitialFragment(AddNearbyContactIntroFragment.newInstance());
+		}
+		viewModel.getRequestBluetoothDiscoverable().observeEvent(this, r ->
+				requestBluetoothDiscoverable()); // never false
+		viewModel.getShowQrCodeFragment().observeEvent(this, show -> {
+			if (show) showQrCodeFragment();
+		});
+		requireNonNull(getSupportActionBar())
+				.setTitle(R.string.add_contact_title);
+		viewModel.getState()
+				.observe(this, this::onAddContactStateChanged);
+	}
+
+	@Override
+	protected void onPostResume() {
+		super.onPostResume();
+		viewModel.setIsActivityResumed(true);
+	}
+
+	@Override
+	protected void onPause() {
+		super.onPause();
+		viewModel.setIsActivityResumed(false);
+	}
+
+	private void onBluetoothDiscoverableResult(boolean discoverable) {
+		if (discoverable) {
+			LOG.info("Bluetooth discoverability was accepted");
+			viewModel.setBluetoothDecision(ACCEPTED);
+		} else {
+			LOG.info("Bluetooth discoverability was refused");
+			viewModel.setBluetoothDecision(REFUSED);
+		}
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
+		}
+		return super.onOptionsItemSelected(item);
+	}
+
+	@Override
+	public void onBackPressed() {
+		if (viewModel.getState().getValue() instanceof Failed) {
+			// re-create this activity when going back in failed state
+			Intent i = new Intent(this, AddNearbyContactActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			startActivity(i);
+		} else {
+			super.onBackPressed();
+		}
+	}
+
+	private void requestBluetoothDiscoverable() {
+		Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+		if (i.resolveActivity(getPackageManager()) != null) {
+			LOG.info("Asking for Bluetooth discoverability");
+			viewModel.setBluetoothDecision(BluetoothDecision.WAITING);
+			bluetoothLauncher.launch(120); // 2min discoverable
+		} else {
+			viewModel.setBluetoothDecision(BluetoothDecision.NO_ADAPTER);
+		}
+	}
+
+	private void showQrCodeFragment() {
+		// FIXME #824
+		FragmentManager fm = getSupportFragmentManager();
+		if (fm.findFragmentByTag(AddNearbyContactFragment.TAG) == null) {
+			BaseFragment f = AddNearbyContactFragment.newInstance();
+			fm.beginTransaction()
+					.replace(R.id.fragmentContainer, f, f.getUniqueTag())
+					.addToBackStack(f.getUniqueTag())
+					.commit();
+		}
+	}
+
+	private void onAddContactStateChanged(@Nullable AddContactState state) {
+		if (state instanceof ContactExchangeFinished) {
+			ContactExchangeResult result =
+					((ContactExchangeFinished) state).result;
+			onContactExchangeResult(result);
+		} else if (state instanceof Failed) {
+			Boolean qrCodeTooOld = ((Failed) state).qrCodeTooOld;
+			onAddingContactFailed(qrCodeTooOld);
+		}
+	}
+
+	private void onContactExchangeResult(ContactExchangeResult result) {
+		if (result instanceof ContactExchangeResult.Success) {
+			Author remoteAuthor =
+					((ContactExchangeResult.Success) result).remoteAuthor;
+			String contactName = remoteAuthor.getName();
+			String text = getString(R.string.contact_added_toast, contactName);
+			Toast.makeText(this, text, LENGTH_LONG).show();
+			supportFinishAfterTransition();
+		} else if (result instanceof ContactExchangeResult.Error) {
+			Author duplicateAuthor =
+					((ContactExchangeResult.Error) result).duplicateAuthor;
+			if (duplicateAuthor == null) {
+				showErrorFragment();
+			} else {
+				String contactName = duplicateAuthor.getName();
+				String text =
+						getString(R.string.contact_already_exists, contactName);
+				Toast.makeText(this, text, LENGTH_LONG).show();
+				supportFinishAfterTransition();
+			}
+		} else throw new AssertionError();
+	}
+
+	private void onAddingContactFailed(@Nullable Boolean qrCodeTooOld) {
+		if (qrCodeTooOld == null) {
+			showErrorFragment();
+		} else {
+			String msg;
+			if (qrCodeTooOld) {
+				msg = getString(R.string.qr_code_too_old,
+						getString(R.string.app_name));
+			} else {
+				msg = getString(R.string.qr_code_too_new,
+						getString(R.string.app_name));
+			}
+			showNextFragment(AddNearbyContactErrorFragment.newInstance(msg));
+		}
+	}
+
+	private void showErrorFragment() {
+		showNextFragment(new AddNearbyContactErrorFragment());
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactErrorFragment.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.content.Intent;
 import android.os.Bundle;
@@ -24,14 +24,14 @@ import static org.briarproject.briar.android.util.UiUtils.onSingleLinkClick;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ContactExchangeErrorFragment extends BaseFragment {
+public class AddNearbyContactErrorFragment extends BaseFragment {
 
 	public static final String TAG =
-			ContactExchangeErrorFragment.class.getName();
+			AddNearbyContactErrorFragment.class.getName();
 	private static final String ERROR_MSG = "errorMessage";
 
-	public static ContactExchangeErrorFragment newInstance(String errorMsg) {
-		ContactExchangeErrorFragment f = new ContactExchangeErrorFragment();
+	public static AddNearbyContactErrorFragment newInstance(String errorMsg) {
+		AddNearbyContactErrorFragment f = new AddNearbyContactErrorFragment();
 		Bundle args = new Bundle();
 		args.putString(ERROR_MSG, errorMsg);
 		f.setArguments(args);
@@ -72,7 +72,7 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		tryAgain.setOnClickListener(view -> {
 			// Recreate the activity so we return to the intro fragment
 			FragmentActivity activity = requireActivity();
-			Intent i = new Intent(activity, ContactExchangeActivity.class);
+			Intent i = new Intent(activity, AddNearbyContactActivity.class);
 			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
 			activity.startActivity(i);
 		});

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactFragment.java

@@ -0,0 +1,202 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.graphics.Bitmap;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.LinearLayout;
+import android.widget.LinearLayout.LayoutParams;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.Failed;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.QrCodeScanned;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.view.QrCodeView;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
+import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
+import static android.widget.LinearLayout.HORIZONTAL;
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactFragment extends BaseFragment
+		implements QrCodeView.FullscreenListener {
+
+	public static final String TAG = AddNearbyContactFragment.class.getName();
+
+	private static final Logger LOG = Logger.getLogger(TAG);
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private CameraView cameraView;
+	private LinearLayout cameraOverlay;
+	private View statusView;
+	private QrCodeView qrCodeView;
+	private TextView status;
+
+	public static AddNearbyContactFragment newInstance() {
+		Bundle args = new Bundle();
+		AddNearbyContactFragment fragment = new AddNearbyContactFragment();
+		fragment.setArguments(args);
+		return fragment;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		return inflater.inflate(R.layout.fragment_keyagreement_qr, container,
+				false);
+	}
+
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		cameraView = view.findViewById(R.id.camera_view);
+		cameraOverlay = view.findViewById(R.id.camera_overlay);
+		statusView = view.findViewById(R.id.status_container);
+		status = view.findViewById(R.id.connect_status);
+		qrCodeView = view.findViewById(R.id.qr_code_view);
+		qrCodeView.setFullscreenListener(this);
+
+		viewModel.getState().observe(getViewLifecycleOwner(),
+				this::onAddContactStateChanged);
+	}
+
+	@Override
+	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+		super.onActivityCreated(savedInstanceState);
+		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
+		cameraView.setPreviewConsumer(viewModel.getQrCodeDecoder());
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		try {
+			cameraView.start();
+		} catch (CameraException e) {
+			logCameraExceptionAndFinish(e);
+		}
+	}
+
+	@Override
+	public void onStop() {
+		super.onStop();
+		try {
+			cameraView.stop();
+		} catch (CameraException e) {
+			logCameraExceptionAndFinish(e);
+		}
+	}
+
+	@Override
+	public void onDestroy() {
+		requireActivity()
+				.setRequestedOrientation(SCREEN_ORIENTATION_UNSPECIFIED);
+		super.onDestroy();
+	}
+
+	@Override
+	public void setFullscreen(boolean fullscreen) {
+		LinearLayout.LayoutParams statusParams, qrCodeParams;
+		if (fullscreen) {
+			// Grow the QR code view to fill its parent
+			statusParams = new LayoutParams(0, 0, 0f);
+			qrCodeParams = new LayoutParams(MATCH_PARENT, MATCH_PARENT, 1f);
+		} else {
+			// Shrink the QR code view to fill half its parent
+			if (cameraOverlay.getOrientation() == HORIZONTAL) {
+				statusParams = new LayoutParams(0, MATCH_PARENT, 1f);
+				qrCodeParams = new LayoutParams(0, MATCH_PARENT, 1f);
+			} else {
+				statusParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+				qrCodeParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+			}
+		}
+		statusView.setLayoutParams(statusParams);
+		qrCodeView.setLayoutParams(qrCodeParams);
+		cameraOverlay.invalidate();
+	}
+
+	@UiThread
+	private void onAddContactStateChanged(@Nullable AddContactState state) {
+		if (state instanceof AddContactState.KeyAgreementListening) {
+			Bitmap qrCode =
+					((AddContactState.KeyAgreementListening) state).qrCode;
+			qrCodeView.setQrCode(qrCode);
+		} else if (state instanceof QrCodeScanned) {
+			try {
+				cameraView.stop();
+			} catch (CameraException e) {
+				logCameraExceptionAndFinish(e);
+			}
+			cameraView.setVisibility(INVISIBLE);
+			statusView.setVisibility(VISIBLE);
+			status.setText(R.string.connecting_to_device);
+		} else if (state instanceof KeyAgreementWaiting) {
+			status.setText(R.string.waiting_for_contact_to_scan);
+		} else if (state instanceof KeyAgreementStarted) {
+			qrCodeView.setVisibility(INVISIBLE);
+			status.setText(R.string.authenticating_with_device);
+		} else if (state instanceof ContactExchangeStarted) {
+			status.setText(R.string.exchanging_contact_details);
+		} else if (state instanceof Failed) {
+			// the activity will replace this fragment with an error fragment
+			statusView.setVisibility(INVISIBLE);
+			cameraView.setVisibility(INVISIBLE);
+		}
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@UiThread
+	private void logCameraExceptionAndFinish(CameraException e) {
+		logException(LOG, WARNING, e);
+		Toast.makeText(getActivity(), R.string.camera_error,
+				LENGTH_LONG).show();
+		finish();
+	}
+
+	@Override
+	protected void finish() {
+		requireActivity().getSupportFragmentManager().popBackStack();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactIntroFragment.java

@@ -0,0 +1,91 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ScrollView;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.fragment.BaseFragment;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts.RequestMultiplePermissions;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.view.View.FOCUS_DOWN;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactIntroFragment extends BaseFragment {
+
+	public static final String TAG =
+			AddNearbyContactIntroFragment.class.getName();
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private AddNearbyContactPermissionManager permissionManager;
+
+	private ScrollView scrollView;
+
+	private final ActivityResultLauncher<String[]> permissionLauncher =
+			registerForActivityResult(new RequestMultiplePermissions(), r ->
+					permissionManager.onRequestPermissionResult(r,
+							viewModel::showQrCodeFragmentIfAllowed));
+
+	public static AddNearbyContactIntroFragment newInstance() {
+		Bundle args = new Bundle();
+		AddNearbyContactIntroFragment
+				fragment = new AddNearbyContactIntroFragment();
+		fragment.setArguments(args);
+		return fragment;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+		permissionManager = new AddNearbyContactPermissionManager(
+				requireActivity(), permissionLauncher::launch,
+				viewModel.isBluetoothSupported());
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+
+		View v = inflater.inflate(R.layout.fragment_keyagreement_id, container,
+				false);
+		scrollView = v.findViewById(R.id.scrollView);
+		View button = v.findViewById(R.id.continueButton);
+		button.setOnClickListener(view -> viewModel.onContinueClicked(() ->
+				permissionManager.checkPermissions()
+		));
+		return v;
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		// Permissions may have been granted manually while we were stopped
+		permissionManager.resetPermissions();
+		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactModule.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
@@ -8,12 +8,12 @@ import dagger.Module;
 import dagger.multibindings.IntoMap;
 
 @Module
-public abstract class ContactExchangeModule {
+public abstract class AddNearbyContactModule {
 
 	@Binds
 	@IntoMap
-	@ViewModelKey(ContactExchangeViewModel.class)
+	@ViewModelKey(AddNearbyContactViewModel.class)
 	abstract ViewModel bindContactExchangeViewModel(
-			ContactExchangeViewModel contactExchangeViewModel);
+			AddNearbyContactViewModel addNearbyContactViewModel);
 
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactPermissionManager.java

@@ -0,0 +1,209 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.content.ActivityNotFoundException;
+import android.content.Context;
+import android.content.Intent;
+import android.location.LocationManager;
+import android.widget.Toast;
+
+import org.briarproject.briar.R;
+
+import java.util.Map;
+
+import androidx.annotation.StringRes;
+import androidx.appcompat.app.AlertDialog;
+import androidx.core.util.Consumer;
+import androidx.fragment.app.FragmentActivity;
+
+import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static android.Manifest.permission.CAMERA;
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS;
+import static android.widget.Toast.LENGTH_LONG;
+import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import static androidx.core.content.ContextCompat.checkSelfPermission;
+import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
+
+public class AddNearbyContactPermissionManager {
+
+	private enum Permission {
+		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
+	}
+
+	private Permission cameraPermission = Permission.UNKNOWN;
+	private Permission locationPermission = Permission.UNKNOWN;
+
+	private final FragmentActivity ctx;
+	private final Consumer<String[]> requestPermissions;
+	private final boolean isBluetoothSupported;
+
+	public AddNearbyContactPermissionManager(FragmentActivity ctx,
+			Consumer<String[]> requestPermissions,
+			boolean isBluetoothSupported) {
+		this.ctx = ctx;
+		this.requestPermissions = requestPermissions;
+		this.isBluetoothSupported = isBluetoothSupported;
+	}
+
+	public void resetPermissions() {
+		cameraPermission = Permission.UNKNOWN;
+		locationPermission = Permission.UNKNOWN;
+	}
+
+	/**
+	 * @return true if location is enabled,
+	 * or it isn't required due to this being a SDK < 28 device.
+	 */
+	static boolean isLocationEnabled(Context ctx) {
+		if (SDK_INT >= 28) {
+			LocationManager lm = ctx.getSystemService(LocationManager.class);
+			return lm.isLocationEnabled();
+		} else {
+			return true;
+		}
+	}
+
+	public static boolean areEssentialPermissionsGranted(Context ctx,
+			boolean isBluetoothSupported) {
+		int ok = PERMISSION_GRANTED;
+		return checkSelfPermission(ctx, CAMERA) == ok &&
+				(SDK_INT < 23 ||
+						checkSelfPermission(ctx, ACCESS_FINE_LOCATION) == ok ||
+						!isBluetoothSupported);
+	}
+
+	private boolean areEssentialPermissionsGranted() {
+		return cameraPermission == Permission.GRANTED &&
+				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
+						!isBluetoothSupported);
+	}
+
+	public boolean checkPermissions() {
+		boolean locationEnabled = isLocationEnabled(ctx);
+		if (locationEnabled && areEssentialPermissionsGranted()) return true;
+		// If an essential permission has been permanently denied, ask the
+		// user to change the setting
+		if (cameraPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(R.string.permission_camera_title,
+					R.string.permission_camera_denied_body);
+			return false;
+		}
+		if (isBluetoothSupported &&
+				locationPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(R.string.permission_location_title,
+					R.string.permission_location_denied_body);
+			return false;
+		}
+		// Should we show the rationale for one or both permissions?
+		if (cameraPermission == Permission.SHOW_RATIONALE &&
+				locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_camera_location_title,
+					R.string.permission_camera_location_request_body);
+		} else if (cameraPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_camera_title,
+					R.string.permission_camera_request_body);
+		} else if (locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_location_title,
+					R.string.permission_location_request_body);
+		} else if (isLocationEnabled(ctx)) {
+			requestPermissions();
+		} else {
+			showLocationDialog(ctx);
+		}
+		return false;
+	}
+
+	private void showDenialDialog(@StringRes int title, @StringRes int body) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setPositiveButton(R.string.ok, getGoToSettingsListener(ctx));
+		builder.setNegativeButton(R.string.cancel,
+				(dialog, which) -> ctx.supportFinishAfterTransition());
+		builder.show();
+	}
+
+	private void showRationale(@StringRes int title, @StringRes int body) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setNeutralButton(R.string.continue_button,
+				(dialog, which) -> requestPermissions());
+		builder.show();
+	}
+
+	private static void showLocationDialog(Context ctx) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(R.string.permission_location_setting_title);
+		builder.setMessage(R.string.permission_location_setting_body);
+		builder.setNegativeButton(R.string.cancel, null);
+		builder.setPositiveButton(R.string.permission_location_setting_button,
+				(dialog, which) -> {
+					Intent i = new Intent(ACTION_LOCATION_SOURCE_SETTINGS);
+					try {
+						ctx.startActivity(i);
+					} catch (ActivityNotFoundException e) {
+						Toast.makeText(ctx, R.string.error_start_activity,
+								LENGTH_LONG).show();
+					}
+				});
+		builder.show();
+	}
+
+	private void requestPermissions() {
+		String[] permissions;
+		if (isBluetoothSupported) {
+			permissions = new String[] {CAMERA, ACCESS_FINE_LOCATION};
+		} else {
+			permissions = new String[] {CAMERA};
+		}
+		requestPermissions.accept(permissions);
+	}
+
+	public void onRequestPermissionResult(Map<String, Boolean> result,
+			Runnable onPermissionsGranted) {
+		if (gotPermission(CAMERA, result)) {
+			cameraPermission = Permission.GRANTED;
+		} else if (shouldShowRationale(CAMERA)) {
+			cameraPermission = Permission.SHOW_RATIONALE;
+		} else {
+			cameraPermission = Permission.PERMANENTLY_DENIED;
+		}
+		if (isBluetoothSupported) {
+			if (gotPermission(ACCESS_FINE_LOCATION, result)) {
+				locationPermission = Permission.GRANTED;
+			} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
+				locationPermission = Permission.SHOW_RATIONALE;
+			} else {
+				locationPermission = Permission.PERMANENTLY_DENIED;
+			}
+		}
+		// If a permission dialog has been shown, showing the QR code fragment
+		// on this call path would cause a crash due to
+		// https://code.google.com/p/android/issues/detail?id=190966.
+		// In that case the isResumed flag prevents the fragment from being
+		// shown here, and showQrCodeFragmentIfAllowed() will be called again
+		// from onPostResume().
+		if (checkPermissions()) onPermissionsGranted.run();
+	}
+
+	private boolean gotPermission(String permission,
+			Map<String, Boolean> result) {
+		Boolean permissionResult = result.get(permission);
+		return permissionResult == null ?
+				isGranted(permission) : permissionResult;
+	}
+
+	private boolean isGranted(String permission) {
+		return checkSelfPermission(ctx, permission) == PERMISSION_GRANTED;
+	}
+
+	private boolean shouldShowRationale(String permission) {
+		return shouldShowRequestPermissionRationale(ctx, permission);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactViewModel.java

@@ -0,0 +1,532 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.app.Application;
+import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.graphics.Bitmap;
+import android.util.DisplayMetrics;
+import android.widget.Toast;
+
+import com.google.zxing.Result;
+
+import org.briarproject.bramble.api.UnsupportedVersionException;
+import org.briarproject.bramble.api.connection.ConnectionManager;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactExchangeManager;
+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.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
+import org.briarproject.bramble.api.keyagreement.Payload;
+import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
+import org.briarproject.bramble.api.keyagreement.PayloadParser;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementAbortedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFailedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStartedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.BluetoothConstants;
+import org.briarproject.bramble.api.plugin.LanTcpConstants;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.Plugin.State;
+import org.briarproject.bramble.api.plugin.PluginManager;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeFinished;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult.Error;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult.Success;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementListening;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+import javax.inject.Provider;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.core.util.Supplier;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.areEssentialPermissionsGranted;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.isLocationEnabled;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.NO_ADAPTER;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.UNKNOWN;
+
+@NotNullByDefault
+class AddNearbyContactViewModel extends AndroidViewModel
+		implements EventListener, QrCodeDecoder.ResultCallback {
+
+	private static final Logger LOG =
+			getLogger(AddNearbyContactViewModel.class.getName());
+
+	enum BluetoothDecision {
+		/**
+		 * We haven't asked the user about Bluetooth discoverability.
+		 */
+		UNKNOWN,
+
+		/**
+		 * The device doesn't have a Bluetooth adapter.
+		 */
+		NO_ADAPTER,
+
+		/**
+		 * We're waiting for the user to accept or refuse discoverability.
+		 */
+		WAITING,
+
+		/**
+		 * The user has accepted discoverability.
+		 */
+		ACCEPTED,
+
+		/**
+		 * The user has refused discoverability.
+		 */
+		REFUSED
+	}
+
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
+	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
+
+	private final EventBus eventBus;
+	private final AndroidExecutor androidExecutor;
+	private final Executor ioExecutor;
+	private final PluginManager pluginManager;
+	private final PayloadEncoder payloadEncoder;
+	private final PayloadParser payloadParser;
+	private final Provider<KeyAgreementTask> keyAgreementTaskProvider;
+	private final ContactExchangeManager contactExchangeManager;
+	private final ConnectionManager connectionManager;
+
+	private final MutableLiveEvent<Boolean> requestBluetoothDiscoverable =
+			new MutableLiveEvent<>();
+	private final MutableLiveEvent<Boolean> showQrCodeFragment =
+			new MutableLiveEvent<>();
+	private final MutableLiveData<AddContactState> state =
+			new MutableLiveData<>();
+
+	private final QrCodeDecoder qrCodeDecoder;
+	private final BroadcastReceiver bluetoothReceiver =
+			new BluetoothStateReceiver();
+
+	@Nullable
+	private final BluetoothAdapter bt;
+	@Nullable
+	private final Plugin wifiPlugin, bluetoothPlugin;
+
+	// UiThread
+	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
+
+	private boolean wasContinueClicked = false;
+	private boolean isActivityResumed = false;
+
+	/**
+	 * Records whether we've enabled the wifi plugin so we don't enable it more
+	 * than once.
+	 */
+	private boolean hasEnabledWifi = false;
+
+	/**
+	 * Records whether we've enabled the Bluetooth plugin so we don't enable it
+	 * more than once.
+	 */
+	private boolean hasEnabledBluetooth = false;
+
+	@Nullable
+	private volatile KeyAgreementTask task;
+	private volatile boolean gotLocalPayload = false, gotRemotePayload = false;
+
+	@Inject
+	AddNearbyContactViewModel(Application app,
+			EventBus eventBus,
+			AndroidExecutor androidExecutor,
+			@IoExecutor Executor ioExecutor,
+			PluginManager pluginManager,
+			PayloadEncoder payloadEncoder,
+			PayloadParser payloadParser,
+			Provider<KeyAgreementTask> keyAgreementTaskProvider,
+			ContactExchangeManager contactExchangeManager,
+			ConnectionManager connectionManager) {
+		super(app);
+		this.eventBus = eventBus;
+		this.androidExecutor = androidExecutor;
+		this.ioExecutor = ioExecutor;
+		this.pluginManager = pluginManager;
+		this.payloadEncoder = payloadEncoder;
+		this.payloadParser = payloadParser;
+		this.keyAgreementTaskProvider = keyAgreementTaskProvider;
+		this.contactExchangeManager = contactExchangeManager;
+		this.connectionManager = connectionManager;
+		bt = BluetoothAdapter.getDefaultAdapter();
+		wifiPlugin = pluginManager.getPlugin(LanTcpConstants.ID);
+		bluetoothPlugin = pluginManager.getPlugin(BluetoothConstants.ID);
+		qrCodeDecoder = new QrCodeDecoder(androidExecutor, ioExecutor, this);
+		eventBus.addListener(this);
+		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
+		getApplication().registerReceiver(bluetoothReceiver, filter);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		getApplication().unregisterReceiver(bluetoothReceiver);
+		eventBus.removeListener(this);
+		stopListening();
+	}
+
+	@UiThread
+	void onContinueClicked(Supplier<Boolean> checkPermissions) {
+		if (bluetoothDecision == REFUSED) {
+			bluetoothDecision = UNKNOWN; // Ask again
+		}
+		wasContinueClicked = true;
+		if (checkPermissions.get()) showQrCodeFragmentIfAllowed();
+	}
+
+	@UiThread
+	boolean isBluetoothSupported() {
+		return bt != null && bluetoothPlugin != null;
+	}
+
+	@UiThread
+	private boolean isWifiReady() {
+		if (wifiPlugin == null) return true; // Continue without wifi
+		State state = wifiPlugin.getState();
+		// Wait for plugin to become enabled
+		return state == ACTIVE || state == INACTIVE;
+	}
+
+	@UiThread
+	private boolean isBluetoothReady() {
+		if (bt == null || bluetoothPlugin == null) {
+			// Continue without Bluetooth
+			return true;
+		}
+		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
+				bluetoothDecision == BluetoothDecision.WAITING ||
+				bluetoothDecision == BluetoothDecision.REFUSED) {
+			// Wait for user to accept
+			return false;
+		}
+		if (bt.getScanMode() != SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
+			// Wait for adapter to become discoverable
+			return false;
+		}
+		// Wait for plugin to become active
+		return bluetoothPlugin.getState() == ACTIVE;
+	}
+
+	@UiThread
+	private void enableWifiIfWeShould() {
+		if (hasEnabledWifi) return;
+		if (wifiPlugin == null) return;
+		State state = wifiPlugin.getState();
+		if (state == STARTING_STOPPING || state == DISABLED) {
+			LOG.info("Enabling wifi plugin");
+			hasEnabledWifi = true;
+			pluginManager.setPluginEnabled(LanTcpConstants.ID, true);
+		}
+	}
+
+	@UiThread
+	private void enableBluetoothIfWeShould() {
+		if (bluetoothDecision != BluetoothDecision.ACCEPTED) return;
+		if (hasEnabledBluetooth) return;
+		if (bluetoothPlugin == null || !isBluetoothSupported()) return;
+		State state = bluetoothPlugin.getState();
+		if (state == STARTING_STOPPING || state == DISABLED) {
+			LOG.info("Enabling Bluetooth plugin");
+			hasEnabledBluetooth = true;
+			pluginManager.setPluginEnabled(BluetoothConstants.ID, true);
+		}
+	}
+
+	@UiThread
+	private void startAddingContact() {
+		// If we return to the intro fragment, the continue button needs to be
+		// clicked again before showing the QR code fragment
+		wasContinueClicked = false;
+		// If we return to the intro fragment, ask for Bluetooth
+		// discoverability again before showing the QR code fragment
+		bluetoothDecision = UNKNOWN;
+		// If we return to the intro fragment, we may need to enable wifi and
+		// Bluetooth again
+		hasEnabledWifi = false;
+		hasEnabledBluetooth = false;
+		// reset state, so we don't show an old QR code again
+		state.setValue(null);
+		// start to listen with a KeyAgreementTask
+		startListening();
+		showQrCodeFragment.setEvent(true);
+	}
+
+	/**
+	 * Call this once Bluetooth and Wi-Fi are ready to be used.
+	 * It is possible to call this more than once over the ViewModel's lifetime.
+	 */
+	@UiThread
+	private void startListening() {
+		KeyAgreementTask oldTask = task;
+		KeyAgreementTask newTask = keyAgreementTaskProvider.get();
+		task = newTask;
+		ioExecutor.execute(() -> {
+			if (oldTask != null) oldTask.stopListening();
+			newTask.listen();
+		});
+	}
+
+	@UiThread
+	private void stopListening() {
+		KeyAgreementTask oldTask = task;
+		ioExecutor.execute(() -> {
+			if (oldTask != null) oldTask.stopListening();
+		});
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof TransportStateEvent) {
+			TransportStateEvent t = (TransportStateEvent) e;
+			if (t.getTransportId().equals(BluetoothConstants.ID)) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Bluetooth state changed to " + t.getState());
+				}
+				showQrCodeFragmentIfAllowed();
+			} else if (t.getTransportId().equals(LanTcpConstants.ID)) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Wifi state changed to " + t.getState());
+				}
+				showQrCodeFragmentIfAllowed();
+			}
+		} else if (e instanceof KeyAgreementListeningEvent) {
+			LOG.info("KeyAgreementListeningEvent received");
+			KeyAgreementListeningEvent event = (KeyAgreementListeningEvent) e;
+			onLocalPayloadReceived(event.getLocalPayload());
+		} else if (e instanceof KeyAgreementWaitingEvent) {
+			LOG.info("KeyAgreementWaitingEvent received");
+			state.setValue(new KeyAgreementWaiting());
+		} else if (e instanceof KeyAgreementStartedEvent) {
+			LOG.info("KeyAgreementStartedEvent received");
+			state.setValue(new KeyAgreementStarted());
+		} else if (e instanceof KeyAgreementFinishedEvent) {
+			LOG.info("KeyAgreementFinishedEvent received");
+			KeyAgreementResult result =
+					((KeyAgreementFinishedEvent) e).getResult();
+			startContactExchange(result);
+			state.setValue(new ContactExchangeStarted());
+		} else if (e instanceof KeyAgreementAbortedEvent) {
+			LOG.info("KeyAgreementAbortedEvent received");
+			resetPayloadFlags();
+			state.setValue(new AddContactState.Failed());
+		} else if (e instanceof KeyAgreementFailedEvent) {
+			LOG.info("KeyAgreementFailedEvent received");
+			resetPayloadFlags();
+			state.setValue(new AddContactState.Failed());
+		}
+	}
+
+	@SuppressWarnings("StatementWithEmptyBody")
+	@UiThread
+	void showQrCodeFragmentIfAllowed() {
+		boolean permissionsGranted = areEssentialPermissionsGranted(
+				getApplication(), isBluetoothSupported());
+		boolean locationEnabled = isLocationEnabled(getApplication());
+		if (isActivityResumed && wasContinueClicked && permissionsGranted &&
+				locationEnabled) {
+			if (isWifiReady() && isBluetoothReady()) {
+				LOG.info("Wifi and Bluetooth are ready");
+				startAddingContact();
+			} else {
+				enableWifiIfWeShould();
+				if (bluetoothDecision == UNKNOWN) {
+					if (isBluetoothSupported()) {
+						requestBluetoothDiscoverable.setEvent(true);
+					} else {
+						bluetoothDecision = NO_ADAPTER;
+					}
+				} else if (bluetoothDecision == REFUSED) {
+					// Ask again when the user clicks "continue"
+				} else {
+					enableBluetoothIfWeShould();
+				}
+			}
+		}
+	}
+
+	/**
+	 * This sets the QR code by setting the state to KeyAgreementListening.
+	 */
+	private void onLocalPayloadReceived(Payload localPayload) {
+		if (gotLocalPayload) return;
+		DisplayMetrics dm = getApplication().getResources().getDisplayMetrics();
+		ioExecutor.execute(() -> {
+			byte[] payloadBytes = payloadEncoder.encode(localPayload);
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Local payload is " + payloadBytes.length
+						+ " bytes");
+			}
+			// Use ISO 8859-1 to encode bytes directly as a string
+			String content = new String(payloadBytes, ISO_8859_1);
+			Bitmap qrCode = QrCodeUtils.createQrCode(dm, content);
+			gotLocalPayload = true;
+			state.postValue(new KeyAgreementListening(qrCode));
+		});
+	}
+
+	@Override
+	@IoExecutor
+	public void onQrCodeDecoded(Result result) {
+		LOG.info("Got result from decoder");
+		// Ignore results until the KeyAgreementTask is ready
+		if (!gotLocalPayload || gotRemotePayload) return;
+		try {
+			byte[] payloadBytes = result.getText().getBytes(ISO_8859_1);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Remote payload is " + payloadBytes.length + " bytes");
+			Payload remotePayload = payloadParser.parse(payloadBytes);
+			gotRemotePayload = true;
+			requireNonNull(task).connectAndRunProtocol(remotePayload);
+			state.postValue(new AddContactState.QrCodeScanned());
+		} catch (UnsupportedVersionException e) {
+			resetPayloadFlags();
+			state.postValue(new AddContactState.Failed(e.isTooOld()));
+		} catch (IOException | IllegalArgumentException e) {
+			LOG.log(WARNING, "QR Code Invalid", e);
+			androidExecutor.runOnUiThread(() -> Toast.makeText(getApplication(),
+					R.string.qr_code_invalid, LENGTH_LONG).show());
+			resetPayloadFlags();
+			state.postValue(new AddContactState.Failed());
+		}
+	}
+
+	private void resetPayloadFlags() {
+		gotRemotePayload = false;
+		gotLocalPayload = false;
+	}
+
+	@UiThread
+	private void startContactExchange(KeyAgreementResult result) {
+		TransportId t = result.getTransportId();
+		DuplexTransportConnection conn = result.getConnection();
+		SecretKey masterKey = result.getMasterKey();
+		boolean alice = result.wasAlice();
+		ioExecutor.execute(() -> {
+			try {
+				Contact contact = contactExchangeManager.exchangeContacts(conn,
+						masterKey, alice, true);
+				// Reuse the connection as a transport connection
+				connectionManager
+						.manageOutgoingConnection(contact.getId(), t, conn);
+				Success success = new Success(contact.getAuthor());
+				state.postValue(new ContactExchangeFinished(success));
+			} catch (ContactExistsException e) {
+				tryToClose(conn);
+				Error error = new Error(e.getRemoteAuthor());
+				state.postValue(new ContactExchangeFinished(error));
+			} catch (DbException | IOException e) {
+				tryToClose(conn);
+				logException(LOG, WARNING, e);
+				Error error = new Error(null);
+				state.postValue(new ContactExchangeFinished(error));
+			}
+		});
+	}
+
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+		@UiThread
+		@Override
+		public void onReceive(Context context, Intent intent) {
+			int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, -1);
+			LOG.info("Bluetooth scan mode changed: " + scanMode);
+			showQrCodeFragmentIfAllowed();
+		}
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getReader().dispose(true, true);
+			conn.getWriter().dispose(true);
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	/**
+	 * Set to true in onPostResume() and false in onPause(). This prevents the
+	 * QR code fragment from being shown if onRequestPermissionsResult() is
+	 * called while the activity is paused, which could cause a crash due to
+	 * https://issuetracker.google.com/issues/37067655.
+	 * TODO check if this is still happening with new permission requesting
+	 */
+	@UiThread
+	void setIsActivityResumed(boolean resumed) {
+		isActivityResumed = resumed;
+		// Workaround for
+		// https://code.google.com/p/android/issues/detail?id=190966
+		showQrCodeFragmentIfAllowed();
+	}
+
+	@UiThread
+	void setBluetoothDecision(BluetoothDecision decision) {
+		bluetoothDecision = decision;
+		showQrCodeFragmentIfAllowed();
+	}
+
+	QrCodeDecoder getQrCodeDecoder() {
+		return qrCodeDecoder;
+	}
+
+	LiveEvent<Boolean> getRequestBluetoothDiscoverable() {
+		return requestBluetoothDiscoverable;
+	}
+
+	LiveEvent<Boolean> getShowQrCodeFragment() {
+		return showQrCodeFragment;
+	}
+
+	/**
+	 * This LiveData will be null initially.
+	 */
+	LiveData<AddContactState> getState() {
+		return state;
+	}
+
+}