WIP make part of keyAgreement public, so it can be used for shard return

* 'social-backup-poc' of https://code.briarproject.org/briar/briar:
  Inject social backup eager singletons when Briar core is created.

.gitlab-ci.yml

@@ -2,6 +2,7 @@ image: briar/ci-image-android:latest
 
 stages:
 - test
+- optional_tests
 - check_reproducibility
 
 test:
@@ -31,3 +32,33 @@ test_reproducible:
     - "curl -X POST -F token=${RELEASE_CHECK_TOKEN} -F ref=master -F variables[RELEASE_TAG]=${CI_COMMIT_REF_NAME} https://code.briarproject.org/api/v4/projects/61/trigger/pipeline"
   only:
     - tags
+
+.optional_tests:
+  stage: optional_tests
+  before_script:
+    - set -e
+    - export GRADLE_USER_HOME=$PWD/.gradle
+
+  cache:
+    paths:
+      - .gradle/wrapper
+      - .gradle/caches
+
+  script:
+    - OPTIONAL_TESTS=org.briarproject.bramble.plugin.tor.BridgeTest ./gradlew --info bramble-java:test --tests BridgeTest
+
+  after_script:
+    # 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/
+
+manual_tests:
+  extends: .optional_tests
+  when: manual
+  except:
+    - tags
+
+pre_release_tests:
+  extends: .optional_tests
+  only:
+    - tags

.idea/dictionaries/briar.xml

@@ -0,0 +1,14 @@
+<component name="ProjectDictionaryState">
+  <dictionary name="briar">
+    <words>
+      <w>briar</w>
+      <w>briarproject</w>
+      <w>emoji</w>
+      <w>encrypter</w>
+      <w>identicon</w>
+      <w>introducee</w>
+      <w>introducer</w>
+      <w>onboarding</w>
+    </words>
+  </dictionary>
+</component>

bramble-android/build.gradle

@@ -11,8 +11,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10214
-		versionName "1.2.14"
+		versionCode 10216
+		versionName "1.2.16"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -38,8 +38,8 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.12@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
+	tor 'org.briarproject:tor-android:0.3.5.13@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
 

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

@@ -31,6 +31,7 @@ public class AndroidUtils {
 	private static final String FAKE_BLUETOOTH_ADDRESS = "02:00:00:00:00:00";
 
 	private static final String STORED_REPORTS = "dev-reports";
+	private static final String STORED_LOGCAT = "dev-logcat";
 
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
@@ -107,6 +108,10 @@ public class AndroidUtils {
 		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
 	}
 
+	public static File getLogcatFile(Context ctx) {
+		return new File(ctx.getFilesDir(), STORED_LOGCAT);
+	}
+
 	/**
 	 * Returns an array of supported content types for image attachments.
 	 * GIFs can't be compressed on API < 24 so they're not supported.

bramble-android/witness.gradle

@@ -75,8 +75,8 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
-        'org.briarproject:tor-android:0.3.5.12:tor-android-0.3.5.12.zip:db71fb3290acff79d572af0752570eaf6aad7c4d88c9b9aa0b4d5afe2b9ead9c',
+        'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a:obfs4proxy-android-0.0.12-dev-40245c4a.zip:8ab05a8f8391be2cb5ab2b665c281a06d9e3a756bd0f95a40a36ca927866ea82',
+        'org.briarproject:tor-android:0.3.5.13:tor-android-0.3.5.13.zip:e0978db136731dae07774b722970cdae1e462fb5adc82845dd80a7e2d87f356c',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.checkerframework:checker-qual:2.8.1:checker-qual-2.8.1.jar:9103499008bcecd4e948da29b17864abb64304e15706444ae209d17ebe0575df',

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/crypto/StreamDecrypterFactory.java

@@ -19,4 +19,10 @@ public interface StreamDecrypterFactory {
 	 */
 	StreamDecrypter createContactExchangeStreamDecrypter(InputStream in,
 			SecretKey headerKey);
+
+	/**
+	 * Creates a {@link StreamDecrypter} for decrypting a log stream.
+	 */
+	StreamDecrypter createLogStreamDecrypter(InputStream in,
+			SecretKey headerKey);
 }

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

@@ -17,6 +17,12 @@ public interface StreamEncrypterFactory {
 	 * Creates a {@link StreamEncrypter} for encrypting a contact exchange
 	 * stream.
 	 */
-	StreamEncrypter createContactExchangeStreamDecrypter(OutputStream out,
+	StreamEncrypter createContactExchangeStreamEncrypter(OutputStream out,
+			SecretKey headerKey);
+
+	/**
+	 * Creates a {@link StreamEncrypter} for encrypting a log stream.
+	 */
+	StreamEncrypter createLogStreamEncrypter(OutputStream out,
 			SecretKey headerKey);
 }

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/reporting/DevConfig.java

@@ -13,4 +13,6 @@ public interface DevConfig {
 	String getDevOnionAddress();
 
 	File getReportDir();
+
+	File getLogcatFile();
 }

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

@@ -16,8 +16,13 @@ public interface StreamReaderFactory {
 
 	/**
 	 * Creates an {@link InputStream InputStream} for reading from a contact
-	 * exchangestream.
+	 * exchange stream.
 	 */
 	InputStream createContactExchangeStreamReader(InputStream in,
 			SecretKey headerKey);
+
+	/**
+	 * Creates an {@link InputStream} for reading from a log stream.
+	 */
+	InputStream createLogStreamReader(InputStream in, SecretKey headerKey);
 }

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

@@ -7,17 +7,19 @@ import java.io.OutputStream;
 
 @NotNullByDefault
 public interface StreamWriterFactory {
-
 	/**
-	 * Creates an {@link OutputStream OutputStream} for writing to a
-	 * transport stream
+	 * Creates a {@link StreamWriter} for writing to a transport stream.
 	 */
 	StreamWriter createStreamWriter(OutputStream out, StreamContext ctx);
 
 	/**
-	 * Creates an {@link OutputStream OutputStream} for writing to a contact
-	 * exchange stream.
+	 * Creates a {@link StreamWriter} for writing to a contact exchange stream.
 	 */
 	StreamWriter createContactExchangeStreamWriter(OutputStream out,
 			SecretKey headerKey);
+
+	/**
+	 * Creates a {@link StreamWriter} for writing to a log stream.
+	 */
+	StreamWriter createLogStreamWriter(OutputStream out, SecretKey headerKey);
 }

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/ScryptKdf.java

@@ -9,14 +9,16 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import static java.lang.Math.min;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 class ScryptKdf implements PasswordBasedKdf {
 
 	private static final Logger LOG =
-			Logger.getLogger(ScryptKdf.class.getName());
+			getLogger(ScryptKdf.class.getName());
 
 	private static final int MIN_COST = 256; // Min parameter N
 	private static final int MAX_COST = 1024 * 1024; // Max parameter N
@@ -33,10 +35,20 @@ class ScryptKdf implements PasswordBasedKdf {
 
 	@Override
 	public int chooseCostParameter() {
+		// Scrypt uses at least 128 * N * r bytes of memory. Don't use more
+		// than half of the JVM's max heap size or we may run out of memory.
+		// https://blog.filippo.io/the-scrypt-parameters/
+		long maxMemory = Runtime.getRuntime().maxMemory();
+		long maxCost = min(MAX_COST, maxMemory / BLOCK_SIZE / 256);
+		if (LOG.isLoggable(INFO) && maxCost < MAX_COST) {
+			LOG.info("Max cost capped at " + maxCost
+					+ " due to max heap size " + maxMemory);
+		}
 		// Increase the cost from min to max while measuring performance
 		int cost = MIN_COST;
-		while (cost * 2 <= MAX_COST && measureDuration(cost) * 2 <= TARGET_MS)
+		while (cost * 2 <= maxCost && measureDuration(cost) * 2 <= TARGET_MS) {
 			cost *= 2;
+		}
 		if (LOG.isLoggable(INFO))
 			LOG.info("KDF cost parameter " + cost);
 		return cost;

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;
@@ -36,4 +37,10 @@ class StreamDecrypterFactoryImpl implements StreamDecrypterFactory {
 			SecretKey headerKey) {
 		return new StreamDecrypterImpl(in, cipherProvider.get(), 0, headerKey);
 	}
+
+	@Override
+	public StreamDecrypter createLogStreamDecrypter(InputStream in,
+			SecretKey headerKey) {
+		return createContactExchangeStreamDecrypter(in, headerKey);
+	}
 }

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;
@@ -51,7 +52,7 @@ class StreamEncrypterFactoryImpl implements StreamEncrypterFactory {
 	}
 
 	@Override
-	public StreamEncrypter createContactExchangeStreamDecrypter(
+	public StreamEncrypter createContactExchangeStreamEncrypter(
 			OutputStream out, SecretKey headerKey) {
 		AuthenticatedCipher cipher = cipherProvider.get();
 		byte[] streamHeaderNonce = new byte[STREAM_HEADER_NONCE_LENGTH];
@@ -60,4 +61,10 @@ class StreamEncrypterFactoryImpl implements StreamEncrypterFactory {
 		return new StreamEncrypterImpl(out, cipher, 0, null, streamHeaderNonce,
 				headerKey, frameKey);
 	}
+
+	@Override
+	public StreamEncrypter createLogStreamEncrypter(OutputStream out,
+			SecretKey headerKey) {
+		return createContactExchangeStreamEncrypter(out, headerKey);
+	}
 }

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/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/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/StreamReaderFactoryImpl.java

@@ -24,15 +24,21 @@ class StreamReaderFactoryImpl implements StreamReaderFactory {
 
 	@Override
 	public InputStream createStreamReader(InputStream in, StreamContext ctx) {
-		return new StreamReaderImpl(
-				streamDecrypterFactory.createStreamDecrypter(in, ctx));
+		return new StreamReaderImpl(streamDecrypterFactory
+				.createStreamDecrypter(in, ctx));
 	}
 
 	@Override
 	public InputStream createContactExchangeStreamReader(InputStream in,
 			SecretKey headerKey) {
-		return new StreamReaderImpl(
-				streamDecrypterFactory.createContactExchangeStreamDecrypter(in,
-						headerKey));
+		return new StreamReaderImpl(streamDecrypterFactory
+				.createContactExchangeStreamDecrypter(in, headerKey));
+	}
+
+	@Override
+	public InputStream createLogStreamReader(InputStream in,
+			SecretKey headerKey) {
+		return new StreamReaderImpl(streamDecrypterFactory
+				.createLogStreamDecrypter(in, headerKey));
 	}
 }

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

@@ -26,15 +26,21 @@ class StreamWriterFactoryImpl implements StreamWriterFactory {
 	@Override
 	public StreamWriter createStreamWriter(OutputStream out,
 			StreamContext ctx) {
-		return new StreamWriterImpl(
-				streamEncrypterFactory.createStreamEncrypter(out, ctx));
+		return new StreamWriterImpl(streamEncrypterFactory
+				.createStreamEncrypter(out, ctx));
 	}
 
 	@Override
 	public StreamWriter createContactExchangeStreamWriter(OutputStream out,
 			SecretKey headerKey) {
-		return new StreamWriterImpl(
-				streamEncrypterFactory.createContactExchangeStreamDecrypter(out,
-						headerKey));
+		return new StreamWriterImpl(streamEncrypterFactory
+				.createContactExchangeStreamEncrypter(out, headerKey));
 	}
-}
+
+	@Override
+	public StreamWriter createLogStreamWriter(OutputStream out,
+			SecretKey headerKey) {
+		return new StreamWriterImpl(streamEncrypterFactory
+				.createLogStreamEncrypter(out, headerKey));
+	}
+}

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;

bramble-java/build.gradle

@@ -16,8 +16,8 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.12@zip'
-	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
+	tor 'org.briarproject:tor:0.3.5.13@zip'
+	tor 'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
 

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/BridgeTest.java

@@ -53,7 +53,7 @@ public class BridgeTest extends BrambleTestCase {
 		return component.getCircumventionProvider().getBridges(false);
 	}
 
-	private final static long TIMEOUT = SECONDS.toMillis(30);
+	private final static long TIMEOUT = SECONDS.toMillis(60);
 
 	private final static Logger LOG = getLogger(BridgeTest.class.getName());
 

bramble-java/witness.gradle

@@ -23,8 +23,8 @@ dependencyVerification {
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
-        'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
-        'org.briarproject:tor:0.3.5.12:tor-0.3.5.12.zip:2f542c4befd216f2226bf7c76e3b8b2d99af6f146a8cb28bf727f42014587006',
+        'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a:obfs4proxy-0.0.12-dev-40245c4a.zip:172029e7058b3a83ac93ac4991a44bf76e16ce8d46f558f5836d57da3cb3a766',
+        'org.briarproject:tor:0.3.5.13:tor-0.3.5.13.zip:1c5f0b821ee2aadb0ea04aa96caab3ca0a08370cce8de81c2dfe04d172f8a2a0',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

briar-android/build.gradle

@@ -22,9 +22,9 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10214
-		versionName "1.2.14"
-		applicationId "org.briarproject.briar.android"
+		versionCode 10216
+		versionName "1.2.16"
+		applicationId "org.briarproject.briar.socialbackup"
 
 		vectorDrawables.useSupportLibrary = true
 		buildConfigField "String", "GitHash",
@@ -101,6 +101,7 @@ 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'
@@ -136,6 +137,7 @@ dependencies {
 	testImplementation "org.jmock:jmock:$jmockVersion"
 	testImplementation "org.jmock:jmock-junit4:$jmockVersion"
 	testImplementation "org.jmock:jmock-legacy:$jmockVersion"
+	testAnnotationProcessor "com.google.dagger:dagger-compiler:2.24"
 
 	androidTestImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	androidTestImplementation 'androidx.test.ext:junit:1.1.2'

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/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

@@ -134,6 +134,42 @@
 			</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.RecoverActivity"
+			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.CustodianHelpRecoverActivity"
+			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.conversation.ConversationActivity"
 			android:label="@string/app_name"

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

@@ -13,6 +13,7 @@ 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;
@@ -34,6 +35,7 @@ import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.attachment.media.MediaModule;
 import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
+import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.view.EmojiTextInputView;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -58,7 +60,9 @@ 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 org.briarproject.briar.socialbackup.SocialBackupManagerImpl_Factory;
 
 import java.util.concurrent.Executor;
 
@@ -179,6 +183,14 @@ public interface AndroidComponent
 
 	AndroidWakeLockManager wakeLockManager();
 
+	CachingLogHandler logHandler();
+
+	Thread.UncaughtExceptionHandler exceptionHandler();
+
+	SocialBackupManager socialBackupManager();
+
+    DatabaseComponent databaseComponent();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

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

@@ -33,11 +33,14 @@ import org.briarproject.briar.android.account.SetupModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.forum.ForumModule;
 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;
-import org.briarproject.briar.android.settings.SettingsModule;
+import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 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.test.TestAvatarCreatorImpl;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -45,6 +48,7 @@ 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;
@@ -72,15 +76,19 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		SetupModule.class,
 		DozeHelperModule.class,
 		ContactExchangeModule.class,
+		LoggingModule.class,
 		LoginModule.class,
 		NavDrawerModule.class,
 		ViewModelModule.class,
 		SettingsModule.class,
 		DevReportModule.class,
 		ContactListModule.class,
+		AndroidDarkCrystalModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
-		ForumModule.BindsModule.class,
+		ForumModule.class,
 		GroupListModule.class,
+		GroupConversationModule.class,
+		SharingModule.class,
 })
 public class AppModule {
 
@@ -188,6 +196,11 @@ public class AppModule {
 			public File getReportDir() {
 				return AndroidUtils.getReportDir(app.getApplicationContext());
 			}
+
+			@Override
+			public File getLogcatFile() {
+				return AndroidUtils.getLogcatFile(app.getApplicationContext());
+			}
 		};
 		return devConfig;
 	}

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

@@ -6,9 +6,6 @@ import android.content.SharedPreferences;
 import org.briarproject.bramble.BrambleApplication;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
 
-import java.util.Collection;
-import java.util.logging.LogRecord;
-
 /**
  * This exists so that the Application object will not necessarily be cast
  * directly to the Briar application object.
@@ -17,8 +14,6 @@ public interface BriarApplication extends BrambleApplication {
 
 	Class<? extends Activity> ENTRY_ACTIVITY = NavDrawerActivity.class;
 
-	Collection<LogRecord> getRecentLogRecords();
-
 	AndroidComponent getApplicationComponent();
 
 	SharedPreferences getDefaultSharedPreferences();

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

@@ -20,12 +20,10 @@ import org.briarproject.bramble.BrambleCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logging.CachingLogHandler;
-import org.briarproject.briar.android.reporting.BriarExceptionHandler;
 import org.briarproject.briar.android.util.UiUtils;
 
-import java.util.Collection;
+import java.lang.Thread.UncaughtExceptionHandler;
 import java.util.logging.Handler;
-import java.util.logging.LogRecord;
 import java.util.logging.Logger;
 
 import androidx.annotation.NonNull;
@@ -42,22 +40,18 @@ public class BriarApplicationImpl extends Application
 	private static final Logger LOG =
 			getLogger(BriarApplicationImpl.class.getName());
 
-	private final CachingLogHandler logHandler = new CachingLogHandler();
-	private final BriarExceptionHandler exceptionHandler =
-			new BriarExceptionHandler(this);
-
 	private AndroidComponent applicationComponent;
 	private volatile SharedPreferences prefs;
 
 	@Override
 	protected void attachBaseContext(Context base) {
-		Thread.setDefaultUncaughtExceptionHandler(exceptionHandler);
 		if (prefs == null)
 			prefs = PreferenceManager.getDefaultSharedPreferences(base);
 		// Loading the language needs to be done here.
 		Localizer.initialize(prefs);
 		super.attachBaseContext(
 				Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 		setTheme(base, prefs);
 	}
 
@@ -67,6 +61,11 @@ public class BriarApplicationImpl extends Application
 
 		if (IS_DEBUG_BUILD) enableStrictMode();
 
+		applicationComponent = createApplicationComponent();
+		UncaughtExceptionHandler exceptionHandler =
+				applicationComponent.exceptionHandler();
+		Thread.setDefaultUncaughtExceptionHandler(exceptionHandler);
+
 		Logger rootLogger = getLogger("");
 		Handler[] handlers = rootLogger.getHandlers();
 		// Disable the Android logger for release builds
@@ -78,12 +77,12 @@ public class BriarApplicationImpl extends Application
 			// Restore the default handlers after the level raising handler
 			for (Handler handler : handlers) rootLogger.addHandler(handler);
 		}
+		CachingLogHandler logHandler = applicationComponent.logHandler();
 		rootLogger.addHandler(logHandler);
 		rootLogger.setLevel(IS_DEBUG_BUILD ? FINE : INFO);
 
 		LOG.info("Created");
 
-		applicationComponent = createApplicationComponent();
 		EmojiManager.install(new GoogleEmojiProvider());
 	}
 
@@ -136,11 +135,6 @@ public class BriarApplicationImpl extends Application
 		return applicationComponent;
 	}
 
-	@Override
-	public Collection<LogRecord> getRecentLogRecords() {
-		return logHandler.getRecentLogRecords();
-	}
-
 	@Override
 	public AndroidComponent getApplicationComponent() {
 		return applicationComponent;

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

@@ -37,7 +37,7 @@ import javax.inject.Inject;
 import androidx.core.app.NotificationCompat;
 
 import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
-import static android.app.NotificationManager.IMPORTANCE_NONE;
+import static android.app.NotificationManager.IMPORTANCE_LOW;
 import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
 import static android.content.Intent.ACTION_SHUTDOWN;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
@@ -46,6 +46,7 @@ import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
+import static android.os.Process.myPid;
 import static androidx.core.app.NotificationCompat.VISIBILITY_SECRET;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -56,8 +57,10 @@ import static org.briarproject.briar.android.BriarApplication.ENTRY_ACTIVITY;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_CHANNEL_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_NOTIFICATION_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_ID;
+import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_OLD_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_NOTIFICATION_ID;
 import static org.briarproject.briar.api.android.LockManager.ACTION_LOCK;
+import static org.briarproject.briar.api.android.LockManager.EXTRA_PID;
 
 public class BriarService extends Service {
 
@@ -120,11 +123,17 @@ public class BriarService extends Service {
 			if (SDK_INT >= 26) {
 				NotificationManager nm = (NotificationManager)
 						requireNonNull(getSystemService(NOTIFICATION_SERVICE));
+				// Delete the old notification channel, which had
+				// IMPORTANCE_NONE and showed a badge
+				nm.deleteNotificationChannel(ONGOING_CHANNEL_OLD_ID);
+				// Use IMPORTANCE_LOW so the system doesn't show its own
+				// notification on API 26-27
 				NotificationChannel ongoingChannel = new NotificationChannel(
 						ONGOING_CHANNEL_ID,
 						getString(R.string.ongoing_notification_title),
-						IMPORTANCE_NONE);
+						IMPORTANCE_LOW);
 				ongoingChannel.setLockscreenVisibility(VISIBILITY_SECRET);
+				ongoingChannel.setShowBadge(false);
 				nm.createNotificationChannel(ongoingChannel);
 				NotificationChannel failureChannel = new NotificationChannel(
 						FAILURE_CHANNEL_ID,
@@ -170,6 +179,7 @@ public class BriarService extends Service {
 	@Override
 	protected void attachBaseContext(Context base) {
 		super.attachBaseContext(Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 	}
 
 	private void showStartupFailureNotification(StartResult result) {
@@ -202,7 +212,12 @@ public class BriarService extends Service {
 	@Override
 	public int onStartCommand(Intent intent, int flags, int startId) {
 		if (ACTION_LOCK.equals(intent.getAction())) {
-			lockManager.setLocked(true);
+			int pid = intent.getIntExtra(EXTRA_PID, -1);
+			if (pid == myPid()) lockManager.setLocked(true);
+			else if (LOG.isLoggable(WARNING)) {
+				LOG.warning("Tried to lock process " + pid + " but this is " +
+						myPid());
+			}
 		}
 		return START_NOT_STICKY; // Don't restart automatically if killed
 	}

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

@@ -68,7 +68,21 @@ public class Localizer {
 			return new Locale(tag);
 	}
 
-	// Returns the localized version of context
+	/*
+	 * Apply localization to the specified context.
+	 *
+	 * It updates the configuration of the context's resources object but can
+	 * also return a new context derived from the context parameter. Hence
+	 * make sure to work with the return value of this method instead of
+	 * the context you passed as a parameter.
+	 *
+	 * This method also has side-effects as it calls Locale#setDefault().
+	 *
+	 * When using this in attachBaseContext() of Application, Service or
+	 * Activity subclasses, it is important to not only apply this method to the
+	 * base Context parameter received in that method, but also apply it on the
+	 * class itself which also extends Context.
+	 */
 	public Context setLocale(Context context) {
 		Resources res = context.getResources();
 		Configuration conf = res.getConfiguration();
@@ -82,7 +96,7 @@ public class Localizer {
 		Locale.setDefault(locale);
 		if (SDK_INT >= 17) {
 			conf.setLocale(locale);
-			context.createConfigurationContext(conf);
+			context = context.createConfigurationContext(conf);
 		} else
 			conf.locale = locale;
 		//noinspection deprecation

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

@@ -32,8 +32,10 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import static android.app.AlarmManager.ELAPSED_REALTIME;
+import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
 import static android.app.PendingIntent.getService;
 import static android.content.Context.ALARM_SERVICE;
+import static android.os.Process.myPid;
 import static android.os.SystemClock.elapsedRealtime;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.logging.Level.WARNING;
@@ -75,23 +77,25 @@ public class LockManagerImpl implements LockManager, Service, EventListener {
 	LockManagerImpl(Application app, SettingsManager settingsManager,
 			AndroidNotificationManager notificationManager,
 			@DatabaseExecutor Executor dbExecutor) {
-		this.appContext = app.getApplicationContext();
+		appContext = app.getApplicationContext();
 		this.settingsManager = settingsManager;
 		this.notificationManager = notificationManager;
 		this.dbExecutor = dbExecutor;
-		this.alarmManager =
+		alarmManager =
 				(AlarmManager) appContext.getSystemService(ALARM_SERVICE);
 		Intent i =
 				new Intent(ACTION_LOCK, null, appContext, BriarService.class);
-		this.lockIntent = getService(appContext, 0, i, 0);
-		this.timeoutNever = Integer.valueOf(
+		i.putExtra(EXTRA_PID, myPid());
+		// When not using FLAG_UPDATE_CURRENT, the intent might have no extras
+		lockIntent = getService(appContext, 0, i, FLAG_UPDATE_CURRENT);
+		timeoutNever = Integer.parseInt(
 				appContext.getString(R.string.pref_lock_timeout_value_never));
-		this.timeoutDefault = Integer.valueOf(
+		timeoutDefault = Integer.parseInt(
 				appContext.getString(R.string.pref_lock_timeout_value_default));
-		this.timeoutMinutes = timeoutNever;
+		timeoutMinutes = timeoutNever;
 
 		// setting this in the constructor makes #getValue() @NonNull
-		this.lockable.setValue(false);
+		lockable.setValue(false);
 	}
 
 	@Override
@@ -148,7 +152,7 @@ public class LockManagerImpl implements LockManager, Service, EventListener {
 		boolean oldValue = lockable.getValue();
 		boolean newValue = hasScreenLock(appContext) && lockableSetting;
 		if (oldValue != newValue) {
-			this.lockable.setValue(newValue);
+			lockable.setValue(newValue);
 		}
 	}
 

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

@@ -0,0 +1,59 @@
+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.RecoverActivity;
+
+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
+		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, RecoverActivity.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/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/UnlockActivity.java

@@ -77,7 +77,7 @@ public class UnlockActivity extends BaseActivity {
 
 	@Override
 	protected void onActivityResult(int requestCode, int resultCode,
-			Intent data) {
+			@Nullable Intent data) {
 		super.onActivityResult(requestCode, resultCode, data);
 		if (requestCode == REQUEST_KEYGUARD_UNLOCK) {
 			if (resultCode == RESULT_OK) unlock();

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

@@ -2,10 +2,13 @@ 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;
@@ -32,7 +35,6 @@ import org.briarproject.briar.android.conversation.ImageFragment;
 import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
-import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
@@ -50,7 +52,6 @@ import org.briarproject.briar.android.navdrawer.TransportsActivity;
 import org.briarproject.briar.android.panic.PanicPreferencesActivity;
 import org.briarproject.briar.android.panic.PanicResponderActivity;
 import org.briarproject.briar.android.privategroup.conversation.GroupActivity;
-import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupActivity;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupFragment;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupModule;
@@ -79,22 +80,32 @@ 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.CustodianDisplayFragment;
+import org.briarproject.briar.android.socialbackup.CustodianHelpRecoverActivity;
+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.OwnerRecoveryModeExplainerFragment;
+import org.briarproject.briar.android.socialbackup.RecoverActivity;
+import org.briarproject.briar.android.socialbackup.ShardQrCodeFragment;
+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.splash.SplashScreenActivity;
 import org.briarproject.briar.android.test.TestDataActivity;
 
 import dagger.Component;
 
 @ActivityScope
-@Component(modules = {
+@Component(modules ={
 		ActivityModule.class,
 		BlogModule.class,
 		CreateGroupModule.class,
-		ForumModule.class,
 		GroupInvitationModule.class,
-		GroupConversationModule.class,
 		GroupMemberModule.class,
 		GroupRevealModule.class,
-		SharingModule.class
+		SharingModule.SharingLegacyModule.class,
+		CreateBackupModule.class
 }, dependencies = AndroidComponent.class)
 public interface ActivityComponent {
 
@@ -186,6 +197,10 @@ public interface ActivityComponent {
 
 	void inject(CrashReportActivity crashReportActivity);
 
+	void inject(NewOrRecoverActivity newOrRecoverActivity);
+
+	void inject(CustodianHelpRecoverActivity custodianHelpRecoverActivity);
+
 	// Fragments
 
 	void inject(AuthorNameFragment fragment);
@@ -242,4 +257,23 @@ public interface ActivityComponent {
 
 	void inject(ConfirmAvatarDialogFragment fragment);
 
+	void inject(ThresholdSelectorFragment thresholdSelectorFragment);
+
+	void inject(ShardQrCodeFragment shardQrCodeFragment);
+
+	void inject(DistributedBackupActivity distributedBackupActivity);
+
+	void inject(RecoverActivity recoverActivity);
+
+	void inject(DatabaseComponent databaseComponent);
+
+	void inject(CustodianSelectorFragment custodianSelectorFragment);
+
+	void inject(ShardsSentFragment shardsSentFragment);
+
+	void inject(OwnerRecoveryModeExplainerFragment ownerRecoveryModeExplainerFragment);
+
+	void inject(ExistingBackupFragment existingBackupFragment);
+
+	void inject(NewOrRecoverFragment newOrRecoverFragment);
 }

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

@@ -14,7 +14,6 @@ import org.briarproject.briar.android.BriarApplication;
 import org.briarproject.briar.android.DestroyableContext;
 import org.briarproject.briar.android.Localizer;
 import org.briarproject.briar.android.controller.ActivityLifecycleController;
-import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.util.UiUtils;
@@ -87,7 +86,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		activityComponent = DaggerActivityComponent.builder()
 				.androidComponent(applicationComponent)
 				.activityModule(getActivityModule())
-				.forumModule(getForumModule())
 				.build();
 		injectActivity(activityComponent);
 		super.onCreate(state);
@@ -111,6 +109,7 @@ public abstract class BaseActivity extends AppCompatActivity
 	protected void attachBaseContext(Context base) {
 		super.attachBaseContext(
 				Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 	}
 
 	public ActivityComponent getActivityComponent() {
@@ -122,11 +121,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		return new ActivityModule(this);
 	}
 
-	// TODO use a test module where this is used in tests
-	protected ForumModule getForumModule() {
-		return new ForumModule();
-	}
-
 	@Override
 	protected void onStart() {
 		super.onStart();

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

@@ -160,7 +160,6 @@ public abstract class BriarActivity extends BaseActivity {
 	 * @param ownLayout true if the custom toolbar brings its own layout
 	 * @return the Toolbar object or null if content view did not contain one
 	 */
-	@Nullable
 	protected Toolbar setUpCustomToolbar(boolean ownLayout) {
 		// Custom Toolbar
 		Toolbar toolbar = findViewById(R.id.toolbar);

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/AddContactViewModel.java

@@ -124,7 +124,7 @@ public class AddContactViewModel extends DbViewModel {
 		return addContactResult;
 	}
 
-	public void updatePendingContact(String name, PendingContact p) {
+	void updatePendingContact(String name, PendingContact p) {
 		runOnDbThread(() -> {
 			try {
 				contactManager.removePendingContact(p.getId());

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/NicknameFragment.java

@@ -29,11 +29,11 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.StringRes;
 import androidx.appcompat.app.AlertDialog.Builder;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
@@ -48,6 +48,7 @@ import static org.briarproject.briar.android.util.UiUtils.getDialogIcon;
 public class NicknameFragment extends BaseFragment {
 
 	private static final String TAG = NicknameFragment.class.getName();
+	private static final String SAVED_LINK = "savedLink";
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
@@ -67,6 +68,20 @@ public class NicknameFragment extends BaseFragment {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddContactViewModel.class);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		if (savedInstanceState != null) {
+			// When the activity (and the ViewModel) get destroyed,
+			// the link will not be available anymore and needs to be restored.
+			// TODO migrate to SavedStateViewModelFactory (once we can use it)
+			String savedLink = savedInstanceState.getString(SAVED_LINK);
+			if (savedLink != null) viewModel.setRemoteHandshakeLink(savedLink);
+		}
 	}
 
 	@Nullable
@@ -74,14 +89,9 @@ public class NicknameFragment extends BaseFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		if (getActivity() == null || getContext() == null) return null;
-
 		View v = inflater.inflate(R.layout.fragment_nickname,
 				container, false);
 
-		viewModel = ViewModelProviders.of(getActivity(), viewModelFactory)
-				.get(AddContactViewModel.class);
-
 		contactNameLayout = v.findViewById(R.id.contactNameLayout);
 		contactNameInput = v.findViewById(R.id.contactNameInput);
 
@@ -93,6 +103,12 @@ public class NicknameFragment extends BaseFragment {
 		return v;
 	}
 
+	@Override
+	public void onSaveInstanceState(@NonNull Bundle outState) {
+		super.onSaveInstanceState(outState);
+		outState.putString(SAVED_LINK, viewModel.getRemoteHandshakeLink());
+	}
+
 	@Nullable
 	private String getNicknameOrNull() {
 		Editable text = contactNameInput.getText();

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -56,8 +56,11 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 
 		Bundle args = requireArguments();
 		byte[] b = args.getByteArray(GROUP_ID);
-		if (b == null) throw new IllegalStateException("No GroupId");
-		groupId = new GroupId(b);
+//		if (b == null) throw new IllegalStateException("No GroupId");
+		// TODO find what the groupId should be when selecting custodians
+		if (b != null) {
+			groupId = new GroupId(b);
+		}
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/contactselection/ContactSelectorFragment.java

@@ -18,7 +18,7 @@ public abstract class ContactSelectorFragment extends
 
 	public static final String TAG = ContactSelectorFragment.class.getName();
 
-	private Menu menu;
+	protected Menu menu;
 
 	@Override
 	protected ContactSelectorAdapter getAdapter(Context context,

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingController.java

@@ -7,6 +7,7 @@ import java.util.Collection;
 
 import androidx.annotation.UiThread;
 
+@Deprecated
 @NotNullByDefault
 public interface SharingController {
 

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingControllerImpl.java

@@ -18,6 +18,7 @@ import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
 
+@Deprecated
 @NotNullByDefault
 public class SharingControllerImpl implements SharingController, EventListener {
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -52,6 +52,7 @@ import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.privategroup.conversation.GroupActivity;
+import org.briarproject.briar.android.socialbackup.CustodianHelpRecoverActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 import org.briarproject.briar.android.view.ImagePreview;
@@ -396,6 +397,12 @@ public class ConversationActivity extends BriarActivity
 			case R.id.action_social_remove_person:
 				askToRemoveContact();
 				return true;
+			case R.id.action_help_recover_account:
+				if (contactId == null) return false;
+				Intent i = new Intent(this, CustodianHelpRecoverActivity.class);
+				i.putExtra(CONTACT_ID, contactId.getInt());
+				startActivity(i);
+				return true;
 			default:
 				return super.onOptionsItemSelected(item);
 		}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationNoticeItem.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.conversation;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.api.conversation.ConversationRequest;
 import org.briarproject.briar.api.conversation.ConversationResponse;
+import org.briarproject.briar.api.socialbackup.ShardMessageHeader;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
@@ -30,6 +31,13 @@ class ConversationNoticeItem extends ConversationItem {
 		this.msgText = null;
 	}
 
+	ConversationNoticeItem(@LayoutRes int layoutRes, String text,
+			ShardMessageHeader r) {
+		super(layoutRes, r);
+		this.text = text;
+		this.msgText = null;
+	}
+
 	@Nullable
 	String getMsgText() {
 		return msgText;

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationVisitor.java

@@ -16,6 +16,7 @@ import org.briarproject.briar.api.introduction.IntroductionResponse;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
+import org.briarproject.briar.api.socialbackup.ShardMessageHeader;
 
 import java.util.List;
 
@@ -292,6 +293,19 @@ class ConversationVisitor implements
 		}
 	}
 
+	@Override
+	public ConversationItem visitShardMessage(ShardMessageHeader r) {
+		if (r.isLocal()) {
+			String text = ctx.getString(R.string.social_backup_shard_sent);
+			return new ConversationNoticeItem(
+					R.layout.list_item_conversation_notice_out, text, r);
+		} else {
+			String text = ctx.getString(R.string.social_backup_shard_received);
+			return new ConversationNoticeItem(
+					R.layout.list_item_conversation_notice_in, text, r);
+		}
+	}
+
 	interface TextCache {
 		@Nullable
 		String getText(MessageId m);

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumActivity.java

@@ -6,52 +6,54 @@ import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
-import android.widget.Toast;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
 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.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.android.forum.ForumController.ForumListener;
 import org.briarproject.briar.android.sharing.ForumSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareForumActivity;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter;
 import org.briarproject.briar.android.threaded.ThreadListActivity;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.forum.Forum;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.widget.Toolbar;
-import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
-import static android.widget.Toast.LENGTH_SHORT;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_FORUM;
+import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.api.forum.ForumConstants.MAX_FORUM_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ForumActivity extends
-		ThreadListActivity<Forum, ForumPostItem, ThreadItemAdapter<ForumPostItem>>
-		implements ForumListener {
+		ThreadListActivity<ForumPostItem, ThreadItemAdapter<ForumPostItem>> {
 
 	@Inject
-	ForumController forumController;
+	ViewModelProvider.Factory viewModelFactory;
+
+	private ForumViewModel viewModel;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(ForumViewModel.class);
 	}
 
 	@Override
-	protected ThreadListController<Forum, ForumPostItem> getController() {
-		return forumController;
+	protected ThreadListViewModel<ForumPostItem> getViewModel() {
+		return viewModel;
+	}
+
+	@Override
+	protected ThreadItemAdapter<ForumPostItem> createAdapter() {
+		return new ThreadItemAdapter<>(this);
 	}
 
 	@Override
@@ -59,36 +61,27 @@ public class ForumActivity extends
 		super.onCreate(state);
 
 		Toolbar toolbar = setUpCustomToolbar(false);
-
-		Intent i = getIntent();
-		String groupName = i.getStringExtra(GROUP_NAME);
-		if (groupName != null) setTitle(groupName);
-		else loadNamedGroup();
-
 		// Open member list on Toolbar click
-		if (toolbar != null) {
-			toolbar.setOnClickListener(v -> {
-				Intent i1 = new Intent(ForumActivity.this,
-						ForumSharingStatusActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-			});
+		toolbar.setOnClickListener(v -> {
+			Intent i = new Intent(ForumActivity.this,
+					ForumSharingStatusActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+		});
+
+		String groupName = getIntent().getStringExtra(GROUP_NAME);
+		if (groupName != null) {
+			setTitle(groupName);
+		} else {
+			observeOnce(viewModel.loadForum(), this, forum ->
+					setTitle(forum.getName())
+			);
 		}
 	}
 
 	@Override
-	protected void onNamedGroupLoaded(Forum forum) {
-		setTitle(forum.getName());
-	}
-
-	@Override
-	protected ThreadItemAdapter<ForumPostItem> createAdapter(
-			LinearLayoutManager layoutManager) {
-		return new ThreadItemAdapter<>(this, layoutManager);
-	}
-
-	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 
 		if (request == REQUEST_SHARE_FORUM && result == RESULT_OK) {
@@ -101,32 +94,31 @@ public class ForumActivity extends
 		// Inflate the menu items for use in the action bar
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.forum_actions, menu);
-
-		return super.onCreateOptionsMenu(menu);
+		super.onCreateOptionsMenu(menu);
+		return true;
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		// Handle presses on the action bar items
-		switch (item.getItemId()) {
-			case R.id.action_forum_share:
-				Intent i2 = new Intent(this, ShareForumActivity.class);
-				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i2.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i2, REQUEST_SHARE_FORUM);
-				return true;
-			case R.id.action_forum_sharing_status:
-				Intent i3 = new Intent(this, ForumSharingStatusActivity.class);
-				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i3.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i3);
-				return true;
-			case R.id.action_forum_delete:
-				showUnsubscribeDialog();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_forum_share) {
+			Intent i = new Intent(this, ShareForumActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_SHARE_FORUM);
+			return true;
+		} else if (itemId == R.id.action_forum_sharing_status) {
+			Intent i = new Intent(this, ForumSharingStatusActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_forum_delete) {
+			showUnsubscribeDialog();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
@@ -135,7 +127,7 @@ public class ForumActivity extends
 	}
 
 	private void showUnsubscribeDialog() {
-		OnClickListener okListener = (dialog, which) -> deleteForum();
+		OnClickListener okListener = (dialog, which) -> viewModel.deleteForum();
 		AlertDialog.Builder builder = new AlertDialog.Builder(this,
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_leave_forum));
@@ -145,27 +137,4 @@ public class ForumActivity extends
 		builder.show();
 	}
 
-	private void deleteForum() {
-		forumController.deleteNamedGroup(
-				new UiResultExceptionHandler<Void, DbException>(this) {
-					@Override
-					public void onResultUi(Void v) {
-						Toast.makeText(ForumActivity.this,
-								R.string.forum_left_toast, LENGTH_SHORT).show();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	public void onForumLeft(ContactId c) {
-		sharingController.remove(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumController.java

@@ -1,18 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.forum.Forum;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-interface ForumController extends ThreadListController<Forum, ForumPostItem> {
-
-	interface ForumListener extends ThreadListListener<ForumPostItem> {
-		@UiThread
-		void onForumLeft(ContactId c);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumControllerImpl.java

@@ -1,185 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-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.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.MessageId;
-import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.forum.ForumController.ForumListener;
-import org.briarproject.briar.android.threaded.ThreadListControllerImpl;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.forum.Forum;
-import org.briarproject.briar.api.forum.ForumInvitationResponse;
-import org.briarproject.briar.api.forum.ForumManager;
-import org.briarproject.briar.api.forum.ForumPost;
-import org.briarproject.briar.api.forum.ForumPostHeader;
-import org.briarproject.briar.api.forum.ForumSharingManager;
-import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
-import org.briarproject.briar.api.sharing.event.ContactLeftShareableEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import static java.lang.Math.max;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@NotNullByDefault
-class ForumControllerImpl extends
-		ThreadListControllerImpl<Forum, ForumPostItem, ForumPostHeader, ForumPost, ForumListener>
-		implements ForumController {
-
-	private static final Logger LOG =
-			Logger.getLogger(ForumControllerImpl.class.getName());
-
-	private final ForumManager forumManager;
-	private final ForumSharingManager forumSharingManager;
-
-	@Inject
-	ForumControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, IdentityManager identityManager,
-			@CryptoExecutor Executor cryptoExecutor,
-			ForumManager forumManager, ForumSharingManager forumSharingManager,
-			EventBus eventBus, Clock clock, MessageTracker messageTracker,
-			AndroidNotificationManager notificationManager) {
-		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
-		this.forumManager = forumManager;
-		this.forumSharingManager = forumSharingManager;
-	}
-
-	@Override
-	public void onActivityStart() {
-		super.onActivityStart();
-		notificationManager.clearForumPostNotification(getGroupId());
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
-
-		if (e instanceof ForumPostReceivedEvent) {
-			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
-			if (f.getGroupId().equals(getGroupId())) {
-				LOG.info("Forum post received, adding...");
-				listener.onItemReceived(buildItem(f.getHeader(), f.getText()));
-			}
-		} else if (e instanceof ForumInvitationResponseReceivedEvent) {
-			ForumInvitationResponseReceivedEvent f =
-					(ForumInvitationResponseReceivedEvent) e;
-			ForumInvitationResponse r = f.getMessageHeader();
-			if (r.getShareableId().equals(getGroupId()) && r.wasAccepted()) {
-				LOG.info("Forum invitation was accepted");
-				listener.onInvitationAccepted(f.getContactId());
-			}
-		} else if (e instanceof ContactLeftShareableEvent) {
-			ContactLeftShareableEvent c = (ContactLeftShareableEvent) e;
-			if (c.getGroupId().equals(getGroupId())) {
-				LOG.info("Forum left by contact");
-				listener.onForumLeft(c.getContactId());
-			}
-		}
-	}
-
-	@Override
-	protected Forum loadNamedGroup() throws DbException {
-		return forumManager.getForum(getGroupId());
-	}
-
-	@Override
-	protected Collection<ForumPostHeader> loadHeaders() throws DbException {
-		return forumManager.getPostHeaders(getGroupId());
-	}
-
-	@Override
-	protected String loadMessageText(ForumPostHeader h) throws DbException {
-		return forumManager.getPostText(h.getId());
-	}
-
-	@Override
-	protected void markRead(MessageId id) throws DbException {
-		forumManager.setReadFlag(getGroupId(), id, true);
-	}
-
-	@Override
-	public void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				Collection<Contact> contacts =
-						forumSharingManager.getSharedWith(getGroupId());
-				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);
-			}
-		});
-	}
-
-	@Override
-	public void createAndStoreMessage(String text,
-			@Nullable ForumPostItem parentItem,
-			ResultExceptionHandler<ForumPostItem, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				GroupCount count = forumManager.getGroupCount(getGroupId());
-				long timestamp = max(count.getLatestMsgTime() + 1,
-						clock.currentTimeMillis());
-				MessageId parentId = parentItem != null ?
-						parentItem.getId() : null;
-				createMessage(text, timestamp, parentId, author, handler);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	private void createMessage(String text, long timestamp,
-			@Nullable MessageId parentId, LocalAuthor author,
-			ResultExceptionHandler<ForumPostItem, DbException> handler) {
-		cryptoExecutor.execute(() -> {
-			LOG.info("Creating forum post...");
-			ForumPost msg = forumManager.createLocalPost(getGroupId(), text,
-					timestamp, parentId, author);
-			storePost(msg, text, handler);
-		});
-	}
-
-	@Override
-	protected ForumPostHeader addLocalMessage(ForumPost p) throws DbException {
-		return forumManager.addLocalPost(p);
-	}
-
-	@Override
-	protected void deleteNamedGroup(Forum forum) throws DbException {
-		forumManager.removeForum(forum);
-	}
-
-	@Override
-	protected ForumPostItem buildItem(ForumPostHeader header, String text) {
-		return new ForumPostItem(header, text);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumModule.java

@@ -1,32 +1,23 @@
 package org.briarproject.briar.android.forum;
 
-import org.briarproject.briar.android.activity.ActivityScope;
-import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
 import androidx.lifecycle.ViewModel;
 import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
 import dagger.multibindings.IntoMap;
 
 @Module
-public class ForumModule {
+public interface ForumModule {
 
-	@Module
-	public interface BindsModule {
-		@Binds
-		@IntoMap
-		@ViewModelKey(ForumListViewModel.class)
-		ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(ForumListViewModel.class)
+	ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
 
-	@ActivityScope
-	@Provides
-	ForumController provideForumController(BaseActivity activity,
-			ForumControllerImpl forumController) {
-		activity.addLifecycleController(forumController);
-		return forumController;
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(ForumViewModel.class)
+	ViewModel bindForumViewModel(ForumViewModel forumViewModel);
 
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumPostItem.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.threaded.ThreadItem;
 import org.briarproject.briar.api.forum.ForumPostHeader;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
 @NotThreadSafe
@@ -17,9 +16,4 @@ class ForumPostItem extends ThreadItem {
 				h.getAuthorInfo(), h.isRead());
 	}
 
-	ForumPostItem(MessageId messageId, @Nullable MessageId parentId,
-			String text, long timestamp, Author author, AuthorInfo authorInfo) {
-		super(messageId, parentId, text, timestamp, author, authorInfo, true);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumViewModel.java

@@ -0,0 +1,231 @@
+package org.briarproject.briar.android.forum;
+
+import android.app.Application;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+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.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.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.forum.Forum;
+import org.briarproject.briar.api.forum.ForumInvitationResponse;
+import org.briarproject.briar.api.forum.ForumManager;
+import org.briarproject.briar.api.forum.ForumPost;
+import org.briarproject.briar.api.forum.ForumPostHeader;
+import org.briarproject.briar.api.forum.ForumSharingManager;
+import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
+import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
+import org.briarproject.briar.api.sharing.event.ContactLeftShareableEvent;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static android.widget.Toast.LENGTH_SHORT;
+import static java.lang.Math.max;
+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;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class ForumViewModel extends ThreadListViewModel<ForumPostItem> {
+
+	private static final Logger LOG = getLogger(ForumViewModel.class.getName());
+
+	private final ForumManager forumManager;
+	private final ForumSharingManager forumSharingManager;
+
+	@Inject
+	ForumViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			SharingController sharingController,
+			@CryptoExecutor Executor cryptoExecutor,
+			Clock clock,
+			MessageTracker messageTracker,
+			EventBus eventBus,
+			ForumManager forumManager,
+			ForumSharingManager forumSharingManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				identityManager, notificationManager, sharingController,
+				cryptoExecutor, clock, messageTracker, eventBus);
+		this.forumManager = forumManager;
+		this.forumSharingManager = forumSharingManager;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ForumPostReceivedEvent) {
+			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
+			if (f.getGroupId().equals(groupId)) {
+				LOG.info("Forum post received, adding...");
+				ForumPostItem item =
+						new ForumPostItem(f.getHeader(), f.getText());
+				addItem(item, false);
+			}
+		} else if (e instanceof ForumInvitationResponseReceivedEvent) {
+			ForumInvitationResponseReceivedEvent f =
+					(ForumInvitationResponseReceivedEvent) e;
+			ForumInvitationResponse r = f.getMessageHeader();
+			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
+				LOG.info("Forum invitation was accepted");
+				sharingController.add(f.getContactId());
+			}
+		} else if (e instanceof ContactLeftShareableEvent) {
+			ContactLeftShareableEvent c = (ContactLeftShareableEvent) e;
+			if (c.getGroupId().equals(groupId)) {
+				LOG.info("Forum left by contact");
+				sharingController.remove(c.getContactId());
+			}
+		} else {
+			super.eventOccurred(e);
+		}
+	}
+
+	protected void clearNotifications() {
+		notificationManager.clearForumPostNotification(groupId);
+	}
+
+	LiveData<Forum> loadForum() {
+		MutableLiveData<Forum> forum = new MutableLiveData<>();
+		runOnDbThread(() -> {
+			try {
+				Forum f = forumManager.getForum(groupId);
+				forum.postValue(f);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+		return forum;
+	}
+
+	@Override
+	public void loadItems() {
+		loadList(txn -> {
+			long start = now();
+			List<ForumPostHeader> headers =
+					forumManager.getPostHeaders(txn, groupId);
+			logDuration(LOG, "Loading headers", start);
+			start = now();
+			List<ForumPostItem> items = new ArrayList<>();
+			for (ForumPostHeader header : headers) {
+				items.add(loadItem(txn, header));
+			}
+			logDuration(LOG, "Loading bodies and creating items", start);
+			return items;
+		}, this::setItems);
+	}
+
+	private ForumPostItem loadItem(Transaction txn, ForumPostHeader header)
+			throws DbException {
+		String text = forumManager.getPostText(txn, header.getId());
+		return new ForumPostItem(header, text);
+	}
+
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable MessageId parentId) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				GroupCount count = forumManager.getGroupCount(groupId);
+				long timestamp = max(count.getLatestMsgTime() + 1,
+						clock.currentTimeMillis());
+				createMessage(text, timestamp, parentId, author);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void createMessage(String text, long timestamp,
+			@Nullable MessageId parentId, LocalAuthor author) {
+		cryptoExecutor.execute(() -> {
+			LOG.info("Creating forum post...");
+			ForumPost msg = forumManager.createLocalPost(groupId, text,
+					timestamp, parentId, author);
+			storePost(msg, text);
+		});
+	}
+
+	private void storePost(ForumPost msg, String text) {
+		runOnDbThread(false, txn -> {
+			long start = now();
+			ForumPostHeader header = forumManager.addLocalPost(txn, msg);
+			logDuration(LOG, "Storing forum post", start);
+			txn.attach(() -> {
+				ForumPostItem item = new ForumPostItem(header, text);
+				addItem(item, true);
+			});
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	@Override
+	protected void markItemRead(ForumPostItem item) {
+		runOnDbThread(() -> {
+			try {
+				forumManager.setReadFlag(groupId, item.getId(), true);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	public void loadSharingContacts() {
+		runOnDbThread(true, txn -> {
+			Collection<Contact> contacts =
+					forumSharingManager.getSharedWith(txn, groupId);
+			Collection<ContactId> contactIds = new ArrayList<>(contacts.size());
+			for (Contact c : contacts) contactIds.add(c.getId());
+			txn.attach(() -> sharingController.addAll(contactIds));
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	void deleteForum() {
+		runOnDbThread(() -> {
+			try {
+				Forum f = forumManager.getForum(groupId);
+				forumManager.removeForum(f);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+		Toast.makeText(getApplication(), R.string.forum_left_toast,
+				LENGTH_SHORT).show();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/CameraException.java

@@ -2,7 +2,7 @@ package org.briarproject.briar.android.keyagreement;
 
 import java.io.IOException;
 
-class CameraException extends IOException {
+public class CameraException extends IOException {
 
 	CameraException(String message) {
 		super(message);

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/QrCodeDecoder.java

@@ -30,7 +30,7 @@ import static java.util.logging.Level.WARNING;
 @SuppressWarnings("deprecation")
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
+public class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
 	private static final Logger LOG =
 			Logger.getLogger(QrCodeDecoder.class.getName());
@@ -41,7 +41,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	private Camera camera = null;
 	private int cameraIndex = 0;
 
-	QrCodeDecoder(ResultCallback callback) {
+	public QrCodeDecoder(ResultCallback callback) {
 		this.callback = callback;
 	}
 
@@ -142,7 +142,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	}
 
 	@NotNullByDefault
-	interface ResultCallback {
+	public interface ResultCallback {
 
 		void handleResult(Result result);
 	}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/QrCodeUtils.java

@@ -21,13 +21,13 @@ import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-class QrCodeUtils {
+public class QrCodeUtils {
 
 	private static final Logger LOG =
 			Logger.getLogger(QrCodeUtils.class.getName());
 
 	@Nullable
-	static Bitmap createQrCode(DisplayMetrics dm, String input) {
+	public static Bitmap createQrCode(DisplayMetrics dm, String input) {
 		int smallestDimen = Math.min(dm.widthPixels, dm.heightPixels);
 		try {
 			// Generate QR code

briar-android/src/main/java/org/briarproject/briar/android/logging/BriefLogFormatter.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
+import java.util.Collection;
 import java.util.Date;
 import java.util.TimeZone;
 import java.util.logging.Formatter;
@@ -17,6 +18,16 @@ import static java.util.Locale.US;
 @NotNullByDefault
 public class BriefLogFormatter extends Formatter {
 
+	public static String formatLog(Formatter formatter,
+			Collection<LogRecord> logRecords) {
+		StringBuilder sb = new StringBuilder();
+		for (LogRecord record : logRecords) {
+			String formatted = formatter.format(record);
+			sb.append(formatted).append('\n');
+		}
+		return sb.toString();
+	}
+
 	private final Object lock = new Object();
 	private final DateFormat dateFormat; // Locking: lock
 	private final Date date; // Locking: lock

briar-android/src/main/java/org/briarproject/briar/android/logging/CachingLogHandler.java

@@ -21,6 +21,10 @@ public class CachingLogHandler extends Handler {
 	// Locking: lock
 	private final Queue<LogRecord> recent = new LinkedList<>();
 
+	// package-private constructor
+	CachingLogHandler() {
+	}
+
 	@Override
 	public void publish(LogRecord record) {
 		synchronized (lock) {

briar-android/src/main/java/org/briarproject/briar/android/logging/LogDecrypter.java

@@ -0,0 +1,16 @@
+package org.briarproject.briar.android.logging;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.AndroidUtils;
+
+import androidx.annotation.Nullable;
+
+@NotNullByDefault
+public interface LogDecrypter {
+	/**
+	 * Returns decrypted log records from {@link AndroidUtils#getLogcatFile}
+	 * or null if there was an error reading the logs.
+	 */
+	@Nullable
+	String decryptLogs(@Nullable byte[] logKey);
+}

briar-android/src/main/java/org/briarproject/briar/android/logging/LogDecrypterImpl.java

@@ -0,0 +1,61 @@
+package org.briarproject.briar.android.logging;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.reporting.DevConfig;
+import org.briarproject.bramble.api.transport.StreamReaderFactory;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Scanner;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+class LogDecrypterImpl implements LogDecrypter {
+
+	private static final Logger LOG =
+			getLogger(LogDecrypterImpl.class.getName());
+
+	private final DevConfig devConfig;
+	private final StreamReaderFactory streamReaderFactory;
+
+	@Inject
+	LogDecrypterImpl(DevConfig devConfig,
+			StreamReaderFactory streamReaderFactory) {
+		this.devConfig = devConfig;
+		this.streamReaderFactory = streamReaderFactory;
+	}
+
+	@Nullable
+	@Override
+	public String decryptLogs(@Nullable byte[] logKey) {
+		if (logKey == null) return null;
+		SecretKey key = new SecretKey(logKey);
+		File logFile = devConfig.getLogcatFile();
+		try (InputStream in = new FileInputStream(logFile)) {
+			InputStream reader =
+					streamReaderFactory.createLogStreamReader(in, key);
+			Scanner s = new Scanner(reader);
+			StringBuilder sb = new StringBuilder();
+			while (s.hasNextLine()) sb.append(s.nextLine()).append("\n");
+			s.close();
+			return sb.toString();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			return null;
+		} finally {
+			//noinspection ResultOfMethodCallIgnored
+			logFile.delete();
+		}
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/logging/LogEncrypter.java

@@ -0,0 +1,16 @@
+package org.briarproject.briar.android.logging;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.util.AndroidUtils;
+
+import androidx.annotation.Nullable;
+
+@NotNullByDefault
+public interface LogEncrypter {
+	/**
+	 * Writes encrypted log records to {@link AndroidUtils#getLogcatFile}
+	 * and returns the encryption key if everything went fine.
+	 */
+	@Nullable
+	byte[] encryptLogs();
+}

briar-android/src/main/java/org/briarproject/briar/android/logging/LogEncrypterImpl.java

@@ -0,0 +1,77 @@
+package org.briarproject.briar.android.logging;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.reporting.DevConfig;
+import org.briarproject.bramble.api.transport.StreamWriter;
+import org.briarproject.bramble.api.transport.StreamWriterFactory;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.logging.Formatter;
+import java.util.logging.LogRecord;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+class LogEncrypterImpl implements LogEncrypter {
+
+	private static final Logger LOG =
+			getLogger(LogEncrypterImpl.class.getName());
+
+	private final DevConfig devConfig;
+	private final CachingLogHandler logHandler;
+	private final CryptoComponent crypto;
+	private final StreamWriterFactory streamWriterFactory;
+
+	@Inject
+	LogEncrypterImpl(DevConfig devConfig,
+			CachingLogHandler logHandler,
+			CryptoComponent crypto,
+			StreamWriterFactory streamWriterFactory) {
+		this.devConfig = devConfig;
+		this.logHandler = logHandler;
+		this.crypto = crypto;
+		this.streamWriterFactory = streamWriterFactory;
+	}
+
+	@Nullable
+	@Override
+	public byte[] encryptLogs() {
+		SecretKey logKey = crypto.generateSecretKey();
+		File logFile = devConfig.getLogcatFile();
+		try (OutputStream out = new FileOutputStream(logFile)) {
+			StreamWriter streamWriter =
+					streamWriterFactory.createLogStreamWriter(out, logKey);
+			Writer writer =
+					new OutputStreamWriter(streamWriter.getOutputStream());
+			writeLogString(writer);
+			writer.close();
+			return logKey.getBytes();
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			return null;
+		}
+	}
+
+	private void writeLogString(Writer writer) throws IOException {
+		Formatter formatter = new BriefLogFormatter();
+		for (LogRecord record : logHandler.getRecentLogRecords()) {
+			String formatted = formatter.format(record);
+			writer.append(formatted).append('\n');
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/logging/LoggingModule.java

@@ -0,0 +1,29 @@
+package org.briarproject.briar.android.logging;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class LoggingModule {
+
+	@Provides
+	@Singleton
+	CachingLogHandler provideCachingLogHandler() {
+		return new CachingLogHandler();
+	}
+
+	@Provides
+	@Singleton
+	LogEncrypter provideLogEncrypter(LogEncrypterImpl logEncrypter) {
+		return logEncrypter;
+	}
+
+	@Provides
+	@Singleton
+	LogDecrypter provideLogDecrypter(LogDecrypterImpl logDecrypter) {
+		return logDecrypter;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/login/StartupActivity.java

@@ -7,6 +7,7 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.BriarService;
+import org.briarproject.briar.android.account.NewOrRecoverActivity;
 import org.briarproject.briar.android.account.SetupActivity;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BaseActivity;
@@ -107,7 +108,7 @@ public class StartupActivity extends BaseActivity implements
 	private void onAccountDeleted() {
 		setResult(RESULT_CANCELED);
 		finish();
-		Intent i = new Intent(this, SetupActivity.class);
+		Intent i = new Intent(this, NewOrRecoverActivity.class);
 		i.addFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP |
 				FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_TASK_ON_HOME);
 		startActivity(i);

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -68,6 +68,7 @@ import static android.view.View.VISIBLE;
 import static androidx.core.view.GravityCompat.START;
 import static androidx.drawerlayout.widget.DrawerLayout.LOCK_MODE_LOCKED_CLOSED;
 import static androidx.fragment.app.FragmentManager.POP_BACK_STACK_INCLUSIVE;
+import static androidx.lifecycle.Lifecycle.State.STARTED;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
@@ -297,6 +298,12 @@ public class NavDrawerActivity extends BriarActivity implements
 				finish();
 			} else if (fm.getBackStackEntryCount() == 0
 					&& fm.findFragmentByTag(ContactListFragment.TAG) == null) {
+				// don't start fragments in the wrong part of lifecycle (#1904)
+				if (!getLifecycle().getCurrentState().isAtLeast(STARTED)) {
+					LOG.warning("Tried to start contacts fragment in state " +
+							getLifecycle().getCurrentState().name());
+					return;
+				}
 				/*
 				 * This makes sure that the first fragment (ContactListFragment) the
 				 * user sees is the same as the last fragment the user sees before

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupActivity.java

@@ -1,67 +1,60 @@
 package org.briarproject.briar.android.privategroup.conversation;
 
-import android.content.DialogInterface;
-import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.LocalAuthor;
 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.controller.handler.UiExceptionHandler;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.android.privategroup.conversation.GroupController.GroupListener;
 import org.briarproject.briar.android.privategroup.creation.GroupInviteActivity;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberListActivity;
 import org.briarproject.briar.android.privategroup.reveal.RevealContactsActivity;
 import org.briarproject.briar.android.threaded.ThreadListActivity;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.Visibility;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.widget.Toolbar;
-import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_GROUP_INVITE;
+import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.api.privategroup.PrivateGroupConstants.MAX_GROUP_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class GroupActivity extends
-		ThreadListActivity<PrivateGroup, GroupMessageItem, GroupMessageAdapter>
-		implements GroupListener, OnClickListener {
+		ThreadListActivity<GroupMessageItem, GroupMessageAdapter> {
 
 	@Inject
-	GroupController controller;
+	ViewModelProvider.Factory viewModelFactory;
 
-	@Nullable
-	private Boolean isCreator = null;
-	private boolean isDissolved = false;
-	private MenuItem revealMenuItem, inviteMenuItem, leaveMenuItem,
-			dissolveMenuItem;
+	private GroupViewModel viewModel;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(GroupViewModel.class);
 	}
 
 	@Override
-	protected ThreadListController<PrivateGroup, GroupMessageItem> getController() {
-		return controller;
+	protected ThreadListViewModel<GroupMessageItem> getViewModel() {
+		return viewModel;
+	}
+
+	@Override
+	protected GroupMessageAdapter createAdapter() {
+		return new GroupMessageAdapter(this);
 	}
 
 	@Override
@@ -69,65 +62,28 @@ public class GroupActivity extends
 		super.onCreate(state);
 
 		Toolbar toolbar = setUpCustomToolbar(false);
-
-		Intent i = getIntent();
-		String groupName = i.getStringExtra(GROUP_NAME);
-		if (groupName != null) setTitle(groupName);
-		loadNamedGroup();
-
 		// Open member list on Toolbar click
-		if (toolbar != null) {
-			toolbar.setOnClickListener(v -> {
-				Intent i1 = new Intent(GroupActivity.this,
-						GroupMemberListActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-			});
-		}
+		toolbar.setOnClickListener(v -> {
+			Intent i = new Intent(GroupActivity.this,
+					GroupMemberListActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+		});
 
+		String groupName = getIntent().getStringExtra(GROUP_NAME);
+		if (groupName != null) setTitle(groupName);
+		observeOnce(viewModel.getPrivateGroup(), this, privateGroup ->
+				setTitle(privateGroup.getName())
+		);
+		observeOnce(viewModel.isCreator(), this, adapter::setIsCreator);
+
+		// start with group disabled and enable when not dissolved
 		setGroupEnabled(false);
-	}
-
-	@Override
-	protected GroupMessageAdapter createAdapter(
-			LinearLayoutManager layoutManager) {
-		return new GroupMessageAdapter(this, layoutManager);
-	}
-
-	@Override
-	protected void loadItems() {
-		controller.isDissolved(
-				new UiResultExceptionHandler<Boolean, DbException>(this) {
-					@Override
-					public void onResultUi(Boolean isDissolved) {
-						setGroupEnabled(!isDissolved);
-						GroupActivity.super.loadItems();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	protected void onNamedGroupLoaded(PrivateGroup group) {
-		setTitle(group.getName());
-		controller.loadLocalAuthor(
-				new UiResultExceptionHandler<LocalAuthor, DbException>(this) {
-					@Override
-					public void onResultUi(LocalAuthor author) {
-						isCreator = group.getCreator().equals(author);
-						adapter.setPerspective(isCreator);
-						showMenuItems();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.isDissolved().observe(this, dissolved -> {
+			setGroupEnabled(!dissolved);
+			// only show dialog when no prior state
+			if (dissolved && state == null) onGroupDissolved();
+		});
 	}
 
 	@Override
@@ -136,74 +92,61 @@ public class GroupActivity extends
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.group_actions, menu);
 
-		revealMenuItem = menu.findItem(R.id.action_group_reveal);
-		inviteMenuItem = menu.findItem(R.id.action_group_invite);
-		leaveMenuItem = menu.findItem(R.id.action_group_leave);
-		dissolveMenuItem = menu.findItem(R.id.action_group_dissolve);
-
-		// all role-dependent items are invisible until we know our role
-		revealMenuItem.setVisible(false);
-		inviteMenuItem.setVisible(false);
-		leaveMenuItem.setVisible(false);
-		dissolveMenuItem.setVisible(false);
-
-		// show items based on role
-		showMenuItems();
-
-		return super.onCreateOptionsMenu(menu);
+		// show items based on role (which will not change, so observe once)
+		observeOnce(viewModel.isCreator(), this, isCreator -> {
+			menu.findItem(R.id.action_group_reveal).setVisible(!isCreator);
+			menu.findItem(R.id.action_group_invite).setVisible(isCreator);
+			menu.findItem(R.id.action_group_leave).setVisible(!isCreator);
+			menu.findItem(R.id.action_group_dissolve).setVisible(isCreator);
+		});
+		super.onCreateOptionsMenu(menu);
+		return true;
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case R.id.action_group_member_list:
-				Intent i1 = new Intent(this, GroupMemberListActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-				return true;
-			case R.id.action_group_reveal:
-				if (isCreator == null || isCreator)
-					throw new IllegalStateException();
-				Intent i2 = new Intent(this, RevealContactsActivity.class);
-				i2.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i2);
-				return true;
-			case R.id.action_group_invite:
-				if (isCreator == null || !isCreator)
-					throw new IllegalStateException();
-				Intent i3 = new Intent(this, GroupInviteActivity.class);
-				i3.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i3, REQUEST_GROUP_INVITE);
-				return true;
-			case R.id.action_group_leave:
-				if (isCreator == null || isCreator)
-					throw new IllegalStateException();
-				showLeaveGroupDialog();
-				return true;
-			case R.id.action_group_dissolve:
-				if (isCreator == null || !isCreator)
-					throw new IllegalStateException();
-				showDissolveGroupDialog();
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_group_member_list) {
+			Intent i = new Intent(this, GroupMemberListActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_group_reveal) {
+			if (requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			Intent i = new Intent(this, RevealContactsActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_group_invite) {
+			if (!requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			Intent i = new Intent(this, GroupInviteActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_GROUP_INVITE);
+			return true;
+		} else if (itemId == R.id.action_group_leave) {
+			if (requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			showLeaveGroupDialog();
+			return true;
+		} else if (itemId == R.id.action_group_dissolve) {
+			if (!requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			showDissolveGroupDialog();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		if (request == REQUEST_GROUP_INVITE && result == RESULT_OK) {
 			displaySnackbar(R.string.groups_invitation_sent);
 		} else super.onActivityResult(request, result, data);
 	}
 
-	@Override
-	public void onItemReceived(GroupMessageItem item) {
-		super.onItemReceived(item);
-		if (item instanceof JoinMessageItem) {
-			if (((JoinMessageItem) item).isInitial()) loadSharingContacts();
-		}
-	}
-
 	@Override
 	protected int getMaxTextLength() {
 		return MAX_GROUP_POST_TEXT_LENGTH;
@@ -211,11 +154,11 @@ public class GroupActivity extends
 
 	@Override
 	public void onReplyClick(GroupMessageItem item) {
-		if (!isDissolved) super.onReplyClick(item);
+		Boolean isDissolved = viewModel.isDissolved().getValue();
+		if (isDissolved != null && !isDissolved) super.onReplyClick(item);
 	}
 
 	private void setGroupEnabled(boolean enabled) {
-		isDissolved = !enabled;
 		sendController.setReady(enabled);
 		list.getRecyclerView().setAlpha(enabled ? 1f : 0.5f);
 
@@ -227,21 +170,13 @@ public class GroupActivity extends
 		}
 	}
 
-	private void showMenuItems() {
-		// we need to have the menu items and know if we are the creator
-		if (leaveMenuItem == null || isCreator == null) return;
-		revealMenuItem.setVisible(!isCreator);
-		inviteMenuItem.setVisible(isCreator);
-		leaveMenuItem.setVisible(!isCreator);
-		dissolveMenuItem.setVisible(isCreator);
-	}
-
 	private void showLeaveGroupDialog() {
 		AlertDialog.Builder builder =
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_leave_dialog_title));
 		builder.setMessage(getString(R.string.groups_leave_dialog_message));
-		builder.setNegativeButton(R.string.dialog_button_leave, this);
+		builder.setNegativeButton(R.string.dialog_button_leave,
+				(d, w) -> deleteGroup());
 		builder.setPositiveButton(R.string.cancel, null);
 		builder.show();
 	}
@@ -251,37 +186,19 @@ public class GroupActivity extends
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_dissolve_dialog_title));
 		builder.setMessage(getString(R.string.groups_dissolve_dialog_message));
-		builder.setNegativeButton(R.string.groups_dissolve_button, this);
+		builder.setNegativeButton(R.string.groups_dissolve_button,
+				(d, w) -> deleteGroup());
 		builder.setPositiveButton(R.string.cancel, null);
 		builder.show();
 	}
 
-	@Override
-	public void onClick(DialogInterface dialog, int which) {
-		controller.deleteNamedGroup(
-				new UiExceptionHandler<DbException>(this) {
-					// The activity is going to be destroyed by the
-					// GroupRemovedEvent being fired
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+	private void deleteGroup() {
+		// The activity is going to be destroyed by the
+		// GroupRemovedEvent being fired
+		viewModel.deletePrivateGroup();
 	}
 
-	@Override
-	public void onContactRelationshipRevealed(AuthorId memberId, ContactId c,
-			Visibility v) {
-		adapter.updateVisibility(memberId, v);
-
-		sharingController.add(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
-	@Override
-	public void onGroupDissolved() {
-		setGroupEnabled(false);
+	private void onGroupDissolved() {
 		AlertDialog.Builder builder =
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_dissolved_dialog_title));

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupController.java

@@ -1,33 +0,0 @@
-package org.briarproject.briar.android.privategroup.conversation;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.Visibility;
-
-import androidx.annotation.UiThread;
-
-public interface GroupController
-		extends ThreadListController<PrivateGroup, GroupMessageItem> {
-
-	void loadLocalAuthor(
-			ResultExceptionHandler<LocalAuthor, DbException> handler);
-
-	void isDissolved(
-			ResultExceptionHandler<Boolean, DbException> handler);
-
-	interface GroupListener extends ThreadListListener<GroupMessageItem> {
-
-		@UiThread
-		void onContactRelationshipRevealed(AuthorId memberId,
-				ContactId contactId, Visibility v);
-
-		@UiThread
-		void onGroupDissolved();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupControllerImpl.java

@@ -1,242 +0,0 @@
-package org.briarproject.briar.android.privategroup.conversation;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-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.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.MessageId;
-import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.privategroup.conversation.GroupController.GroupListener;
-import org.briarproject.briar.android.threaded.ThreadListControllerImpl;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.privategroup.GroupMember;
-import org.briarproject.briar.api.privategroup.GroupMessage;
-import org.briarproject.briar.api.privategroup.GroupMessageFactory;
-import org.briarproject.briar.api.privategroup.GroupMessageHeader;
-import org.briarproject.briar.api.privategroup.JoinMessageHeader;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.PrivateGroupManager;
-import org.briarproject.briar.api.privategroup.event.ContactRelationshipRevealedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupDissolvedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
-import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import static java.lang.Math.max;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-class GroupControllerImpl extends
-		ThreadListControllerImpl<PrivateGroup, GroupMessageItem, GroupMessageHeader, GroupMessage, GroupListener>
-		implements GroupController {
-
-	private static final Logger LOG =
-			Logger.getLogger(GroupControllerImpl.class.getName());
-
-	private final PrivateGroupManager privateGroupManager;
-	private final GroupMessageFactory groupMessageFactory;
-
-	@Inject
-	GroupControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, IdentityManager identityManager,
-			@CryptoExecutor Executor cryptoExecutor,
-			PrivateGroupManager privateGroupManager,
-			GroupMessageFactory groupMessageFactory, EventBus eventBus,
-			MessageTracker messageTracker, Clock clock,
-			AndroidNotificationManager notificationManager) {
-		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
-		this.privateGroupManager = privateGroupManager;
-		this.groupMessageFactory = groupMessageFactory;
-	}
-
-	@Override
-	public void onActivityStart() {
-		super.onActivityStart();
-		notificationManager.clearGroupMessageNotification(getGroupId());
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
-
-		if (e instanceof GroupMessageAddedEvent) {
-			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
-			if (!g.isLocal() && g.getGroupId().equals(getGroupId())) {
-				LOG.info("Group message received, adding...");
-				listener.onItemReceived(buildItem(g.getHeader(), g.getText()));
-			}
-		} else if (e instanceof ContactRelationshipRevealedEvent) {
-			ContactRelationshipRevealedEvent c =
-					(ContactRelationshipRevealedEvent) e;
-			if (getGroupId().equals(c.getGroupId())) {
-				listener.onContactRelationshipRevealed(c.getMemberId(),
-						c.getContactId(), c.getVisibility());
-			}
-		} else if (e instanceof GroupInvitationResponseReceivedEvent) {
-			GroupInvitationResponseReceivedEvent g =
-					(GroupInvitationResponseReceivedEvent) e;
-			GroupInvitationResponse r = g.getMessageHeader();
-			if (getGroupId().equals(r.getShareableId()) && r.wasAccepted()) {
-				listener.onInvitationAccepted(g.getContactId());
-			}
-		} else if (e instanceof GroupDissolvedEvent) {
-			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
-			if (getGroupId().equals(g.getGroupId())) {
-				listener.onGroupDissolved();
-			}
-		}
-	}
-
-	@Override
-	protected PrivateGroup loadNamedGroup() throws DbException {
-		return privateGroupManager.getPrivateGroup(getGroupId());
-	}
-
-	@Override
-	protected Collection<GroupMessageHeader> loadHeaders() throws DbException {
-		return privateGroupManager.getHeaders(getGroupId());
-	}
-
-	@Override
-	protected String loadMessageText(GroupMessageHeader header)
-			throws DbException {
-		if (header instanceof JoinMessageHeader) {
-			// will be looked up later
-			return "";
-		}
-		return privateGroupManager.getMessageText(header.getId());
-	}
-
-	@Override
-	protected void markRead(MessageId id) throws DbException {
-		privateGroupManager.setReadFlag(getGroupId(), id, true);
-	}
-
-	@Override
-	public void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				Collection<GroupMember> members =
-						privateGroupManager.getMembers(getGroupId());
-				Collection<ContactId> contactIds = new ArrayList<>();
-				for (GroupMember m : members) {
-					if (m.getContactId() != null)
-						contactIds.add(m.getContactId());
-				}
-				handler.onResult(contactIds);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void createAndStoreMessage(String text,
-			@Nullable GroupMessageItem parentItem,
-			ResultExceptionHandler<GroupMessageItem, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				MessageId parentId = null;
-				MessageId previousMsgId =
-						privateGroupManager.getPreviousMsgId(getGroupId());
-				GroupCount count =
-						privateGroupManager.getGroupCount(getGroupId());
-				long timestamp = count.getLatestMsgTime();
-				if (parentItem != null) parentId = parentItem.getId();
-				timestamp = max(clock.currentTimeMillis(), timestamp + 1);
-				createMessage(text, timestamp, parentId, author, previousMsgId,
-						handler);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	private void createMessage(String text, long timestamp,
-			@Nullable MessageId parentId, LocalAuthor author,
-			MessageId previousMsgId,
-			ResultExceptionHandler<GroupMessageItem, DbException> handler) {
-		cryptoExecutor.execute(() -> {
-			LOG.info("Creating group message...");
-			GroupMessage msg = groupMessageFactory
-					.createGroupMessage(getGroupId(), timestamp,
-							parentId, author, text, previousMsgId);
-			storePost(msg, text, handler);
-		});
-	}
-
-	@Override
-	protected GroupMessageHeader addLocalMessage(GroupMessage message)
-			throws DbException {
-		return privateGroupManager.addLocalMessage(message);
-	}
-
-	@Override
-	protected void deleteNamedGroup(PrivateGroup group) throws DbException {
-		privateGroupManager.removePrivateGroup(group.getId());
-	}
-
-	@Override
-	protected GroupMessageItem buildItem(GroupMessageHeader header,
-			String text) {
-		if (header instanceof JoinMessageHeader) {
-			return new JoinMessageItem((JoinMessageHeader) header, text);
-		}
-		return new GroupMessageItem(header, text);
-	}
-
-	@Override
-	public void loadLocalAuthor(
-			ResultExceptionHandler<LocalAuthor, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				handler.onResult(author);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void isDissolved(
-			ResultExceptionHandler<Boolean, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				boolean isDissolved =
-						privateGroupManager.isDissolved(getGroupId());
-				handler.onResult(isDissolved);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupConversationModule.java

@@ -1,19 +1,18 @@
 package org.briarproject.briar.android.privategroup.conversation;
 
-import org.briarproject.briar.android.activity.ActivityScope;
-import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
+import dagger.multibindings.IntoMap;
 
 @Module
-public class GroupConversationModule {
+public interface GroupConversationModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(GroupViewModel.class)
+	ViewModel bindGroupViewModel(GroupViewModel groupViewModel);
 
-	@ActivityScope
-	@Provides
-	GroupController provideGroupController(BaseActivity activity,
-			GroupControllerImpl groupController) {
-		activity.addLifecycleController(groupController);
-		return groupController;
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupMessageAdapter.java

@@ -4,19 +4,14 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
-import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.threaded.BaseThreadItemViewHolder;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter;
 import org.briarproject.briar.android.threaded.ThreadPostViewHolder;
-import org.briarproject.briar.api.privategroup.Visibility;
 
 import androidx.annotation.LayoutRes;
 import androidx.annotation.UiThread;
-import androidx.recyclerview.widget.LinearLayoutManager;
-
-import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
 
 @UiThread
 @NotNullByDefault
@@ -24,15 +19,14 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 
 	private boolean isCreator = false;
 
-	GroupMessageAdapter(ThreadItemListener<GroupMessageItem> listener,
-			LinearLayoutManager layoutManager) {
-		super(listener, layoutManager);
+	GroupMessageAdapter(ThreadItemListener<GroupMessageItem> listener) {
+		super(listener);
 	}
 
 	@LayoutRes
 	@Override
 	public int getItemViewType(int position) {
-		GroupMessageItem item = items.get(position);
+		GroupMessageItem item = getItem(position);
 		return item.getLayout();
 	}
 
@@ -47,30 +41,9 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 		return new ThreadPostViewHolder<>(v);
 	}
 
-	void setPerspective(boolean isCreator) {
+	void setIsCreator(boolean isCreator) {
 		this.isCreator = isCreator;
 		notifyDataSetChanged();
 	}
 
-	void updateVisibility(AuthorId memberId, Visibility v) {
-		int position = findItemPosition(memberId);
-		if (position != NO_POSITION) {
-			GroupMessageItem item = items.get(position);
-			if (item instanceof JoinMessageItem) {
-				((JoinMessageItem) item).setVisibility(v);
-				notifyItemChanged(findItemPosition(item), item);
-			}
-		}
-	}
-
-	private int findItemPosition(AuthorId a) {
-		int count = items.size();
-		for (int i = 0; i < count; i++) {
-			GroupMessageItem item = items.get(i);
-			if (item.getAuthor().getId().equals(a))
-				return i;
-		}
-		return NO_POSITION; // Not found
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupViewModel.java

@@ -0,0 +1,287 @@
+package org.briarproject.briar.android.privategroup.conversation;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+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.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.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.privategroup.GroupMember;
+import org.briarproject.briar.api.privategroup.GroupMessage;
+import org.briarproject.briar.api.privategroup.GroupMessageFactory;
+import org.briarproject.briar.api.privategroup.GroupMessageHeader;
+import org.briarproject.briar.api.privategroup.JoinMessageHeader;
+import org.briarproject.briar.api.privategroup.PrivateGroup;
+import org.briarproject.briar.api.privategroup.PrivateGroupManager;
+import org.briarproject.briar.api.privategroup.event.ContactRelationshipRevealedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupDissolvedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupInvitationResponseReceivedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
+import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.lang.Math.max;
+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;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
+
+	private static final Logger LOG = getLogger(GroupViewModel.class.getName());
+
+	private final PrivateGroupManager privateGroupManager;
+	private final GroupMessageFactory groupMessageFactory;
+
+	private final MutableLiveData<PrivateGroup> privateGroup =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> isCreator = new MutableLiveData<>();
+	private final MutableLiveData<Boolean> isDissolved =
+			new MutableLiveData<>();
+
+	@Inject
+	GroupViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			SharingController sharingController,
+			@CryptoExecutor Executor cryptoExecutor,
+			Clock clock,
+			MessageTracker messageTracker,
+			PrivateGroupManager privateGroupManager,
+			GroupMessageFactory groupMessageFactory) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				identityManager, notificationManager, sharingController,
+				cryptoExecutor, clock, messageTracker, eventBus);
+		this.privateGroupManager = privateGroupManager;
+		this.groupMessageFactory = groupMessageFactory;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof GroupMessageAddedEvent) {
+			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
+			// only act on non-local messages in this group
+			if (!g.isLocal() && g.getGroupId().equals(groupId)) {
+				LOG.info("Group message received, adding...");
+				GroupMessageItem item = buildItem(g.getHeader(), g.getText());
+				addItem(item, false);
+				// In case the join message comes from the creator,
+				// we need to reload the sharing contacts
+				// in case it was delayed and the sharing count is wrong (#850).
+				if (item instanceof JoinMessageItem &&
+						(((JoinMessageItem) item).isInitial())) {
+					loadSharingContacts();
+				}
+			}
+		} else if (e instanceof GroupInvitationResponseReceivedEvent) {
+			GroupInvitationResponseReceivedEvent g =
+					(GroupInvitationResponseReceivedEvent) e;
+			GroupInvitationResponse r = g.getMessageHeader();
+			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
+				sharingController.add(g.getContactId());
+			}
+		} else if (e instanceof ContactRelationshipRevealedEvent) {
+			ContactRelationshipRevealedEvent c =
+					(ContactRelationshipRevealedEvent) e;
+			if (c.getGroupId().equals(groupId)) {
+				sharingController.add(c.getContactId());
+			}
+		} else if (e instanceof GroupDissolvedEvent) {
+			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
+			if (g.getGroupId().equals(groupId)) {
+				isDissolved.setValue(true);
+			}
+		} else {
+			super.eventOccurred(e);
+		}
+	}
+
+	@Override
+	protected void performInitialLoad() {
+		super.performInitialLoad();
+		loadPrivateGroup(groupId);
+	}
+
+	protected void clearNotifications() {
+		notificationManager.clearGroupMessageNotification(groupId);
+	}
+
+	private void loadPrivateGroup(GroupId groupId) {
+		runOnDbThread(() -> {
+			try {
+				PrivateGroup g = privateGroupManager.getPrivateGroup(groupId);
+				privateGroup.postValue(g);
+				Author author = identityManager.getLocalAuthor();
+				isCreator.postValue(g.getCreator().equals(author));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@Override
+	public void loadItems() {
+		loadList(txn -> {
+			// check first if group is dissolved
+			isDissolved
+					.postValue(privateGroupManager.isDissolved(txn, groupId));
+			// now continue to load the items
+			long start = now();
+			List<GroupMessageHeader> headers =
+					privateGroupManager.getHeaders(txn, groupId);
+			logDuration(LOG, "Loading headers", start);
+			start = now();
+			List<GroupMessageItem> items = new ArrayList<>();
+			for (GroupMessageHeader header : headers) {
+				items.add(loadItem(txn, header));
+			}
+			logDuration(LOG, "Loading bodies and creating items", start);
+			return items;
+		}, this::setItems);
+	}
+
+	private GroupMessageItem loadItem(Transaction txn,
+			GroupMessageHeader header) throws DbException {
+		String text;
+		if (header instanceof JoinMessageHeader) {
+			// will be looked up later
+			text = "";
+		} else {
+			text = privateGroupManager.getMessageText(txn, header.getId());
+		}
+		return buildItem(header, text);
+	}
+
+	private GroupMessageItem buildItem(GroupMessageHeader header, String text) {
+		if (header instanceof JoinMessageHeader) {
+			return new JoinMessageItem((JoinMessageHeader) header, text);
+		}
+		return new GroupMessageItem(header, text);
+	}
+
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable MessageId parentId) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				MessageId previousMsgId =
+						privateGroupManager.getPreviousMsgId(groupId);
+				GroupCount count = privateGroupManager.getGroupCount(groupId);
+				long timestamp = count.getLatestMsgTime();
+				timestamp = max(clock.currentTimeMillis(), timestamp + 1);
+				createMessage(text, timestamp, parentId, author, previousMsgId);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void createMessage(String text, long timestamp,
+			@Nullable MessageId parentId, LocalAuthor author,
+			MessageId previousMsgId) {
+		cryptoExecutor.execute(() -> {
+			LOG.info("Creating group message...");
+			GroupMessage msg = groupMessageFactory.createGroupMessage(groupId,
+					timestamp, parentId, author, text, previousMsgId);
+			storePost(msg, text);
+		});
+	}
+
+	private void storePost(GroupMessage msg, String text) {
+		runOnDbThread(false, txn -> {
+			long start = now();
+			GroupMessageHeader header =
+					privateGroupManager.addLocalMessage(txn, msg);
+			logDuration(LOG, "Storing group message", start);
+			txn.attach(() ->
+					addItem(buildItem(header, text), true)
+			);
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	@Override
+	protected void markItemRead(GroupMessageItem item) {
+		runOnDbThread(() -> {
+			try {
+				privateGroupManager.setReadFlag(groupId, item.getId(), true);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	public void loadSharingContacts() {
+		runOnDbThread(true, txn -> {
+			Collection<GroupMember> members =
+					privateGroupManager.getMembers(txn, groupId);
+			Collection<ContactId> contactIds = new ArrayList<>();
+			for (GroupMember m : members) {
+				if (m.getContactId() != null)
+					contactIds.add(m.getContactId());
+			}
+			txn.attach(() -> sharingController.addAll(contactIds));
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	void deletePrivateGroup() {
+		runOnDbThread(() -> {
+			try {
+				privateGroupManager.removePrivateGroup(groupId);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<PrivateGroup> getPrivateGroup() {
+		return privateGroup;
+	}
+
+	LiveData<Boolean> isCreator() {
+		return isCreator;
+	}
+
+	LiveData<Boolean> isDissolved() {
+		return isDissolved;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/JoinMessageItem.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.privategroup.conversation;
 
 import org.briarproject.briar.R;
 import org.briarproject.briar.api.privategroup.JoinMessageHeader;
-import org.briarproject.briar.api.privategroup.Visibility;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
@@ -13,13 +12,11 @@ import androidx.annotation.UiThread;
 @NotThreadSafe
 class JoinMessageItem extends GroupMessageItem {
 
-	private Visibility visibility;
 	private final boolean isInitial;
 
 	JoinMessageItem(JoinMessageHeader h, String text) {
 		super(h, text);
-		this.visibility = h.getVisibility();
-		this.isInitial = h.isInitial();
+		isInitial = h.isInitial();
 	}
 
 	@Override
@@ -33,14 +30,6 @@ class JoinMessageItem extends GroupMessageItem {
 		return R.layout.list_item_group_join_notice;
 	}
 
-	Visibility getVisibility() {
-		return visibility;
-	}
-
-	void setVisibility(Visibility visibility) {
-		this.visibility = visibility;
-	}
-
 	boolean isInitial() {
 		return isInitial;
 	}

briar-android/src/main/java/org/briarproject/briar/android/reporting/BriarExceptionHandler.java

@@ -1,29 +1,40 @@
 package org.briarproject.briar.android.reporting;
 
-import android.content.Context;
+import android.app.Application;
 import android.os.Process;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.logging.LogEncrypter;
 
 import java.lang.Thread.UncaughtExceptionHandler;
 
+import javax.inject.Inject;
+
 import static org.briarproject.briar.android.util.UiUtils.startDevReportActivity;
 
 @NotNullByDefault
-public class BriarExceptionHandler implements UncaughtExceptionHandler {
+class BriarExceptionHandler implements UncaughtExceptionHandler {
 
-	private final Context ctx;
+	private final Application app;
+	private final LogEncrypter logEncrypter;
 	private final long appStartTime;
 
-	public BriarExceptionHandler(Context ctx) {
-		this.ctx = ctx;
-		this.appStartTime = System.currentTimeMillis();
+	@Inject
+	BriarExceptionHandler(Application app, LogEncrypter logEncrypter) {
+		this.app = app;
+		this.logEncrypter = logEncrypter;
+		appStartTime = System.currentTimeMillis();
 	}
 
 	@Override
 	public void uncaughtException(Thread t, Throwable e) {
+		// encrypt logs to disk before handing over to new process
+		// the intent has limited space, so we can't reliably store them there.
+		byte[] logKey = logEncrypter.encryptLogs();
+
 		// activity runs in its own process, so we can kill the old one
-		startDevReportActivity(ctx, CrashReportActivity.class, e, appStartTime);
+		startDevReportActivity(app.getApplicationContext(),
+				CrashReportActivity.class, e, appStartTime, logKey);
 		Process.killProcess(Process.myPid());
 		System.exit(10);
 	}

briar-android/src/main/java/org/briarproject/briar/android/reporting/BriarReportCollector.java

@@ -25,8 +25,6 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.BuildConfig;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.logging.BriefLogFormatter;
 import org.briarproject.briar.android.reporting.ReportData.MultiReportInfo;
 import org.briarproject.briar.android.reporting.ReportData.ReportItem;
 import org.briarproject.briar.android.reporting.ReportData.SingleReportInfo;
@@ -41,8 +39,6 @@ import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
-import java.util.logging.Formatter;
-import java.util.logging.LogRecord;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -74,8 +70,8 @@ class BriarReportCollector {
 		this.ctx = ctx;
 	}
 
-	public ReportData collectReportData(@Nullable Throwable t,
-			long appStartTime) {
+	ReportData collectReportData(@Nullable Throwable t, long appStartTime,
+			String logs) {
 		ReportData reportData = new ReportData()
 				.add(getBasicInfo(t))
 				.add(getDeviceInfo());
@@ -86,7 +82,7 @@ class BriarReportCollector {
 				.add(getStorage())
 				.add(getConnectivity())
 				.add(getBuildConfig())
-				.add(getLogcat())
+				.add(getLogcat(logs))
 				.add(getDeviceFeatures());
 	}
 
@@ -313,15 +309,8 @@ class BriarReportCollector {
 				buildConfig);
 	}
 
-	private ReportItem getLogcat() {
-		BriarApplication app = (BriarApplication) ctx.getApplicationContext();
-		StringBuilder sb = new StringBuilder();
-		Formatter formatter = new BriefLogFormatter();
-		for (LogRecord record : app.getRecentLogRecords()) {
-			sb.append(formatter.format(record)).append('\n');
-		}
-		return new ReportItem("Logcat", R.string.dev_report_logcat,
-				sb.toString());
+	private ReportItem getLogcat(String logs) {
+		return new ReportItem("Logcat", R.string.dev_report_logcat, logs);
 	}
 
 	private ReportItem getDeviceFeatures() {

briar-android/src/main/java/org/briarproject/briar/android/reporting/CrashReportActivity.java

@@ -35,6 +35,7 @@ public class CrashReportActivity extends BaseActivity
 
 	public static final String EXTRA_THROWABLE = "throwable";
 	public static final String EXTRA_APP_START_TIME = "appStartTime";
+	public static final String EXTRA_APP_LOGCAT = "logcat";
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
@@ -56,7 +57,8 @@ public class CrashReportActivity extends BaseActivity
 		Intent intent = getIntent();
 		Throwable t = (Throwable) intent.getSerializableExtra(EXTRA_THROWABLE);
 		long appStartTime = intent.getLongExtra(EXTRA_APP_START_TIME, -1);
-		viewModel.init(t, appStartTime);
+		byte[] logKey = intent.getByteArrayExtra(EXTRA_APP_LOGCAT);
+		viewModel.init(t, appStartTime, logKey);
 		viewModel.getShowReport().observeEvent(this, show -> {
 			if (show) displayFragment(true);
 		});

briar-android/src/main/java/org/briarproject/briar/android/reporting/DevReportModule.java

@@ -15,4 +15,8 @@ public abstract class DevReportModule {
 	@ViewModelKey(ReportViewModel.class)
 	abstract ViewModel bindReportViewModel(ReportViewModel reportViewModel);
 
+	@Binds
+	abstract Thread.UncaughtExceptionHandler bindUncaughtExceptionHandler(
+			BriarExceptionHandler handler);
+
 }

briar-android/src/main/java/org/briarproject/briar/android/reporting/ReportViewModel.java

@@ -11,6 +11,9 @@ import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.logging.BriefLogFormatter;
+import org.briarproject.briar.android.logging.CachingLogHandler;
+import org.briarproject.briar.android.logging.LogDecrypter;
 import org.briarproject.briar.android.reporting.ReportData.MultiReportInfo;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
@@ -19,6 +22,7 @@ import org.json.JSONException;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.util.UUID;
+import java.util.logging.Formatter;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
@@ -36,13 +40,16 @@ import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+import static org.briarproject.briar.android.logging.BriefLogFormatter.formatLog;
 
 @NotNullByDefault
-public class ReportViewModel extends AndroidViewModel {
+class ReportViewModel extends AndroidViewModel {
 
 	private static final Logger LOG =
 			getLogger(ReportViewModel.class.getName());
 
+	private final CachingLogHandler logHandler;
+	private final LogDecrypter logDecrypter;
 	private final BriarReportCollector collector;
 	private final DevReporter reporter;
 	private final PluginManager pluginManager;
@@ -58,18 +65,39 @@ public class ReportViewModel extends AndroidViewModel {
 	private boolean isFeedback;
 
 	@Inject
-	public ReportViewModel(@NonNull Application application,
-			DevReporter reporter, PluginManager pluginManager) {
+	ReportViewModel(@NonNull Application application,
+			CachingLogHandler logHandler,
+			LogDecrypter logDecrypter,
+			DevReporter reporter,
+			PluginManager pluginManager) {
 		super(application);
-		this.collector = new BriarReportCollector(application);
+		collector = new BriarReportCollector(application);
+		this.logHandler = logHandler;
+		this.logDecrypter = logDecrypter;
 		this.reporter = reporter;
 		this.pluginManager = pluginManager;
 	}
 
-	void init(@Nullable Throwable t, long appStartTime) {
+	void init(@Nullable Throwable t, long appStartTime,
+			@Nullable byte[] logKey) {
 		isFeedback = t == null;
 		if (reportData.getValue() == null) new SingleShotAndroidExecutor(() -> {
-			ReportData data = collector.collectReportData(t, appStartTime);
+			String decryptedLogs;
+			if (isFeedback) {
+				Formatter formatter = new BriefLogFormatter();
+				decryptedLogs =
+						formatLog(formatter, logHandler.getRecentLogRecords());
+			} else {
+				decryptedLogs = logDecrypter.decryptLogs(logKey);
+				if (decryptedLogs == null) {
+					// error decrypting logs, get logs from this process
+					Formatter formatter = new BriefLogFormatter();
+					decryptedLogs = formatLog(formatter,
+							logHandler.getRecentLogRecords());
+				}
+			}
+			ReportData data =
+					collector.collectReportData(t, appStartTime, decryptedLogs);
 			reportData.postValue(data);
 		}).start();
 	}
@@ -110,8 +138,8 @@ public class ReportViewModel extends AndroidViewModel {
 	}
 
 	/**
-	 * The content of the report
-	 * that will be loaded after {@link #init(Throwable, long)} was called.
+	 * The content of the report that will be loaded after
+	 * {@link #init(Throwable, long, byte[])} was called.
 	 */
 	LiveData<ReportData> getReportData() {
 		return reportData;

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingController.java

@@ -0,0 +1,54 @@
+package org.briarproject.briar.android.sharing;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+
+@NotNullByDefault
+public interface SharingController {
+
+	/**
+	 * Call this when the owning ViewModel gets cleared,
+	 * so the {@link EventBus} can get unregistered.
+	 */
+	void onCleared();
+
+	/**
+	 * Adds one contact to be tracked.
+	 */
+	@UiThread
+	void add(ContactId c);
+
+	/**
+	 * Adds a collection of contacts to be tracked.
+	 */
+	@UiThread
+	void addAll(Collection<ContactId> contacts);
+
+	/**
+	 * Call this when the contact identified by c is no longer sharing
+	 * the given group identified by GroupId g.
+	 */
+	@UiThread
+	void remove(ContactId c);
+
+	/**
+	 * Returns the total number of contacts that have been added.
+	 */
+	LiveData<SharingInfo> getSharingInfo();
+
+	class SharingInfo {
+		public final int total, online;
+
+		SharingInfo(int total, int online) {
+			this.total = total;
+			this.online = online;
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingControllerImpl.java

@@ -0,0 +1,102 @@
+package org.briarproject.briar.android.sharing;
+
+import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.ContactId;
+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.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+@NotNullByDefault
+public class SharingControllerImpl implements SharingController, EventListener {
+
+	private final EventBus eventBus;
+	private final ConnectionRegistry connectionRegistry;
+
+	// UI thread
+	private final Set<ContactId> contacts = new HashSet<>();
+	private final MutableLiveData<SharingInfo> sharingInfo =
+			new MutableLiveData<>();
+
+	@Inject
+	SharingControllerImpl(EventBus eventBus,
+			ConnectionRegistry connectionRegistry) {
+		this.eventBus = eventBus;
+		this.connectionRegistry = connectionRegistry;
+		eventBus.addListener(this);
+	}
+
+	@Override
+	public void onCleared() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactConnectedEvent) {
+			setConnected(((ContactConnectedEvent) e).getContactId());
+		} else if (e instanceof ContactDisconnectedEvent) {
+			setConnected(((ContactDisconnectedEvent) e).getContactId());
+		}
+	}
+
+	@UiThread
+	private void setConnected(ContactId c) {
+		if (contacts.contains(c)) {
+			updateLiveData();
+		}
+	}
+
+	@UiThread
+	private void updateLiveData() {
+		int online = getOnlineCount();
+		sharingInfo.setValue(new SharingInfo(contacts.size(), online));
+	}
+
+	private int getOnlineCount() {
+		int online = 0;
+		for (ContactId c : contacts) {
+			if (connectionRegistry.isConnected(c)) online++;
+		}
+		return online;
+	}
+
+	@UiThread
+	@Override
+	public void addAll(Collection<ContactId> c) {
+		contacts.addAll(c);
+		updateLiveData();
+	}
+
+	@UiThread
+	@Override
+	public void add(ContactId c) {
+		contacts.add(c);
+		updateLiveData();
+	}
+
+	@UiThread
+	@Override
+	public void remove(ContactId c) {
+		contacts.remove(c);
+		updateLiveData();
+	}
+
+	@Override
+	public LiveData<SharingInfo> getSharingInfo() {
+		return sharingInfo;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingModule.java

@@ -9,36 +9,47 @@ import dagger.Provides;
 @Module
 public class SharingModule {
 
-	@ActivityScope
-	@Provides
-	ShareForumController provideShareForumController(
-			ShareForumControllerImpl shareForumController) {
-		return shareForumController;
+	@Module
+	@Deprecated
+	public static class SharingLegacyModule {
+
+		@ActivityScope
+		@Provides
+		ShareForumController provideShareForumController(
+				ShareForumControllerImpl shareForumController) {
+			return shareForumController;
+		}
+
+		@ActivityScope
+		@Provides
+		BlogInvitationController provideInvitationBlogController(
+				BaseActivity activity,
+				BlogInvitationControllerImpl blogInvitationController) {
+			activity.addLifecycleController(blogInvitationController);
+			return blogInvitationController;
+		}
+
+		@ActivityScope
+		@Provides
+		ForumInvitationController provideInvitationForumController(
+				BaseActivity activity,
+				ForumInvitationControllerImpl forumInvitationController) {
+			activity.addLifecycleController(forumInvitationController);
+			return forumInvitationController;
+		}
+
+		@ActivityScope
+		@Provides
+		ShareBlogController provideShareBlogController(
+				ShareBlogControllerImpl shareBlogController) {
+			return shareBlogController;
+		}
 	}
 
-	@ActivityScope
 	@Provides
-	BlogInvitationController provideInvitationBlogController(
-			BaseActivity activity,
-			BlogInvitationControllerImpl blogInvitationController) {
-		activity.addLifecycleController(blogInvitationController);
-		return blogInvitationController;
-	}
-
-	@ActivityScope
-	@Provides
-	ForumInvitationController provideInvitationForumController(
-			BaseActivity activity,
-			ForumInvitationControllerImpl forumInvitationController) {
-		activity.addLifecycleController(forumInvitationController);
-		return forumInvitationController;
-	}
-
-	@ActivityScope
-	@Provides
-	ShareBlogController provideShareBlogController(
-			ShareBlogControllerImpl shareBlogController) {
-		return shareBlogController;
+	SharingController provideSharingController(
+			SharingControllerImpl sharingController) {
+		return sharingController;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/CustodianHelpRecoverActivity.java

@@ -0,0 +1,67 @@
+package org.briarproject.briar.android.socialbackup;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+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.api.socialbackup.SocialBackupManager;
+
+import javax.inject.Inject;
+
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+
+public class CustodianHelpRecoverActivity extends BriarActivity implements
+		BaseFragment.BaseFragmentListener, CustodianScanQrButtonListener {
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Inject
+	public SocialBackupManager socialBackupManager;
+
+	@Inject
+	public DatabaseComponent db;
+
+	@Override
+	public void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		setContentView(R.layout.activity_recover); // TODO change this
+
+		Intent intent = getIntent();
+		int id = intent.getIntExtra(CONTACT_ID, -1);
+		if (id == -1) throw new IllegalStateException("No ContactId");
+		ContactId contactId = new ContactId(id);
+
+		// check if we have a shard for this secret owner
+		try {
+			db.transaction(false, txn -> {
+				if (!socialBackupManager.amCustodian(txn, contactId)) {
+					throw new DbException();
+				}
+				CustodianRecoveryModeExplainerFragment fragment =
+						new CustodianRecoveryModeExplainerFragment();
+				showInitialFragment(fragment);
+			});
+		} catch (DbException e) {
+			// TODO improve this
+			Toast.makeText(this,
+					"You do not hold a backup shard from this contact",
+					Toast.LENGTH_SHORT).show();
+			finish();
+		}
+	}
+
+	@Override
+	public void scanQrButtonClicked() {
+		// TODO scan qr code
+		finish();
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/CustodianRecoveryModeExplainerFragment.java

@@ -0,0 +1,51 @@
+package org.briarproject.briar.android.socialbackup;
+
+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.android.fragment.BaseFragment;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import org.briarproject.briar.R;
+
+public class CustodianRecoveryModeExplainerFragment extends BaseFragment {
+
+	protected CustodianScanQrButtonListener listener;
+
+	public static final String TAG = CustodianRecoveryModeExplainerFragment.class.getName();
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		requireActivity().setTitle(R.string.title_help_recover);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(@NonNull LayoutInflater inflater, @Nullable
+			ViewGroup container, @Nullable Bundle savedInstanceState) {
+		View view = inflater.inflate(R.layout.fragment_recovery_custodian_explainer,
+				container, false);
+
+		Button button = view.findViewById(R.id.button);
+		button.setOnClickListener(e -> listener.scanQrButtonClicked());
+		return view;
+	}
+
+	@Override
+	public void onAttach(Context context) {
+		super.onAttach(context);
+		listener = (CustodianScanQrButtonListener) context;
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+}
+

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/CustodianScanQrButtonListener.java

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

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/CustodianSelectorFragment.java

@@ -0,0 +1,93 @@
+package org.briarproject.briar.android.socialbackup;
+
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.ContactId;
+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.socialbackup.creation.CreateBackupController;
+import org.briarproject.briar.android.contactselection.BaseContactSelectorAdapter;
+import org.briarproject.briar.android.contactselection.ContactSelectorController;
+import org.briarproject.briar.android.contactselection.ContactSelectorFragment;
+import org.briarproject.briar.android.contactselection.SelectableContactItem;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+
+import java.util.Collection;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+
+import static java.util.Objects.requireNonNull;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class CustodianSelectorFragment extends ContactSelectorFragment {
+
+	public static final String TAG = CustodianSelectorFragment.class.getName();
+
+	@Inject
+	CreateBackupController controller;
+
+	public static CustodianSelectorFragment newInstance() {
+		Bundle args = new Bundle();
+
+		CustodianSelectorFragment fragment = new CustodianSelectorFragment();
+		fragment.setArguments(args);
+
+		return fragment;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		requireActivity().setTitle(R.string.title_select_custodians);
+	}
+
+	@Override
+	protected ContactSelectorController<SelectableContactItem> getController() {
+		return controller;
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	protected void onSelectionChanged() {
+		super.onSelectionChanged();
+		if (menu == null) return;
+		MenuItem item = menu.findItem(R.id.action_contacts_selected);
+		if (item == null) return;
+
+		BaseContactSelectorAdapter a = adapter;
+		selectedContacts = a.getSelectedContactIds();
+
+		int n = selectedContacts.size();
+		int min = 2;
+		boolean enough = n >= min;
+
+		item.setVisible(enough);
+		if (n == 0) {
+			Toast.makeText(getContext(), String.format(getString(R.string.select_at_least_n_contacts), min),
+					Toast.LENGTH_SHORT).show();
+		} else if (n < min) {
+			Toast.makeText(getContext(), String.format(getString(R.string.select_at_least_n_more_contacts), min - n),
+					Toast.LENGTH_SHORT).show();
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/DarkCrystalImpl.java

@@ -0,0 +1,56 @@
+package org.briarproject.briar.android.socialbackup;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.api.socialbackup.Shard;
+import org.briarproject.briar.api.socialbackup.DarkCrystal;
+import org.magmacollective.darkcrystal.secretsharingwrapper.SecretSharingWrapper;
+
+import java.security.GeneralSecurityException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Random;
+
+import javax.inject.Inject;
+
+import dagger.Provides;
+
+import static org.briarproject.briar.socialbackup.SocialBackupConstants.SECRET_ID_BYTES;
+
+@NotNullByDefault
+public class DarkCrystalImpl implements DarkCrystal {
+
+    @Inject
+	DarkCrystalImpl() {
+	}
+
+	@Override
+	public List<Shard> createShards(SecretKey secret, int numShards,
+			int threshold) {
+		Random random = new Random();
+		byte[] secretId = new byte[SECRET_ID_BYTES];
+		random.nextBytes(secretId);
+		List<byte[]> shardsBytes = SecretSharingWrapper.share(secret.getBytes(), numShards, threshold);
+		List<Shard> shards = new ArrayList<>(numShards);
+		for (byte[] shardBytes : shardsBytes) {
+			shards.add(new Shard(secretId, shardBytes));
+		}
+		return shards;
+	}
+
+	@Override
+	public SecretKey combineShards(List<Shard> shards) throws
+			GeneralSecurityException {
+		// Check each shard has the same secret Id
+		byte[] secretId = shards.get(0).getSecretId();
+		for (Shard shard : shards) {
+			if (!Arrays.equals(shard.getSecretId(), secretId)) throw new GeneralSecurityException();
+		}
+        List<byte[]> shardsBytes = new ArrayList<>(shards.size());
+		for (Shard shard : shards) {
+			shardsBytes.add(shard.getShard());
+		}
+		byte[] secretBytes = SecretSharingWrapper.combine(shardsBytes);
+		return new SecretKey(secretBytes);
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/DistributedBackupActivity.java

@@ -0,0 +1,91 @@
+package org.briarproject.briar.android.socialbackup;
+
+import android.os.Bundle;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.contactselection.ContactSelectorListener;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.api.socialbackup.BackupMetadata;
+import org.briarproject.briar.api.socialbackup.SocialBackupManager;
+
+import java.util.Collection;
+import java.util.List;
+
+import javax.inject.Inject;
+
+public class DistributedBackupActivity extends BriarActivity implements
+		BaseFragment.BaseFragmentListener, ContactSelectorListener,
+		ThresholdDefinedListener,
+		ShardsSentFragment.ShardsSentDismissedListener {
+
+	private Collection<ContactId> custodians;
+
+	@Inject
+	public SocialBackupManager socialBackupManager;
+
+	@Inject
+	public DatabaseComponent db;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		setContentView(R.layout.activity_distributed_backup);
+
+		try {
+			db.transaction(false, txn -> {
+				BackupMetadata backupMetadata =
+						socialBackupManager.getBackupMetadata(txn);
+				if (backupMetadata == null) throw new DbException();
+				ExistingBackupFragment fragment =
+						ExistingBackupFragment.newInstance(backupMetadata);
+				showInitialFragment(fragment);
+			});
+		} catch (DbException e) {
+			CustodianSelectorFragment fragment =
+					CustodianSelectorFragment.newInstance();
+			showInitialFragment(fragment);
+		}
+	}
+
+	@Override
+	public void contactsSelected(Collection<ContactId> contacts) {
+		Toast.makeText(this,
+				String.format("selected %d contacts", contacts.size()),
+				Toast.LENGTH_SHORT).show();
+		custodians = contacts;
+		ThresholdSelectorFragment fragment =
+				ThresholdSelectorFragment.newInstance(contacts.size());
+		showNextFragment(fragment);
+	}
+
+	@Override
+	public void thresholdDefined(int threshold) {
+		try {
+			db.transaction(false, txn -> {
+				socialBackupManager
+						.createBackup(txn, (List<ContactId>) custodians,
+								threshold);
+				ShardsSentFragment fragment = new ShardsSentFragment();
+				showNextFragment(fragment);
+			});
+		} catch (DbException e) {
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public void shardsSentDismissed() {
+		finish();
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/ExistingBackupFragment.java

@@ -0,0 +1,85 @@
+package org.briarproject.briar.android.socialbackup;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.api.socialbackup.BackupMetadata;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+public class ExistingBackupFragment extends BaseFragment {
+
+	private static final String THRESHOLD = "threshold";
+	private static final String CUSTODIANS = "custodians";
+	public static final String TAG = ExistingBackupFragment.class.getName();
+
+	public static ExistingBackupFragment newInstance(
+			BackupMetadata backupMetadata) {
+		Bundle bundle = new Bundle();
+		List<Author> custodians = backupMetadata.getCustodians();
+		ArrayList custodianNames = new ArrayList();
+	    for (Author custodian : custodians) {
+	    	custodianNames.add(custodian.getName());
+	    }
+	    bundle.putStringArrayList(CUSTODIANS, custodianNames);
+		bundle.putInt(THRESHOLD, backupMetadata.getThreshold());
+		ExistingBackupFragment fragment = new ExistingBackupFragment();
+		fragment.setArguments(bundle);
+		return fragment;
+	}
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		requireActivity().setTitle(R.string.title_distributed_backup);
+
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(@NonNull LayoutInflater inflater, @Nullable
+			ViewGroup container, @Nullable Bundle savedInstanceState) {
+		View view = inflater.inflate(R.layout.fragment_existing_backup,
+				container, false);
+		Bundle args = requireArguments();
+        ArrayList<String> custodianNames = args.getStringArrayList(CUSTODIANS);
+        String custodianNamesString = "";
+        for (String custodianName : custodianNames) {
+          	custodianNamesString += custodianName + ", ";
+        }
+        TextView textViewThreshold = view.findViewById(R.id.textViewThreshold);
+        textViewThreshold.setText(String.format("%d of %d contacts needed to restore account", args.getInt(THRESHOLD), custodianNames.size()));
+        TextView textViewCustodians = view.findViewById(R.id.textViewCustodians);
+        textViewCustodians.setText(custodianNamesString);
+		return view;
+	}
+
+	@Override
+	public void onAttach(Context context) {
+		super.onAttach(context);
+//		listener = (ShardsSentDismissedListener) context;
+	}
+
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+}