Add new module to integration tests.

Add ImageActivity to show image attachment in full-screen

See merge request briar/briar!999

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

@@ -18,8 +18,8 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.IoUtils;
 
-import java.io.Closeable;
 import java.io.IOException;
 import java.security.SecureRandom;
 import java.util.ArrayList;
@@ -51,7 +51,6 @@ import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
@@ -161,11 +160,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 	@Override
 	void tryToClose(@Nullable BluetoothServerSocket ss) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
+		IoUtils.tryToClose(ss, LOG, WARNING);
 	}
 
 	@Override
@@ -195,7 +190,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			s.connect();
 			return wrapSocket(s);
 		} catch (IOException e) {
-			tryToClose(s);
+			IoUtils.tryToClose(s, LOG, WARNING);
 			throw e;
 		}
 	}
@@ -268,14 +263,6 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return addresses;
 	}
 
-	private void tryToClose(@Nullable Closeable c) {
-		try {
-			if (c != null) c.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private class BluetoothStateReceiver extends BroadcastReceiver {
 
 		@Override

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.system;
 
+import android.annotation.SuppressLint;
 import android.app.Application;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
@@ -26,7 +27,7 @@ import static android.provider.Settings.Secure.ANDROID_ID;
 
 @Immutable
 @NotNullByDefault
-class AndroidSecureRandomProvider extends LinuxSecureRandomProvider {
+class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 
 	private static final int SEED_LENGTH = 32;
 
@@ -37,6 +38,7 @@ class AndroidSecureRandomProvider extends LinuxSecureRandomProvider {
 		appContext = app.getApplicationContext();
 	}
 
+	@SuppressLint("HardwareIds")
 	@Override
 	protected void writeToEntropyPool(DataOutputStream out) throws IOException {
 		super.writeToEntropyPool(out);
@@ -49,12 +51,14 @@ class AndroidSecureRandomProvider extends LinuxSecureRandomProvider {
 		String id = Settings.Secure.getString(contentResolver, ANDROID_ID);
 		if (id != null) out.writeUTF(id);
 		Parcel parcel = Parcel.obtain();
-		WifiManager wm =
-				(WifiManager) appContext.getSystemService(WIFI_SERVICE);
-		List<WifiConfiguration> configs = wm.getConfiguredNetworks();
-		if (configs != null) {
-			for (WifiConfiguration config : configs)
-				parcel.writeParcelable(config, 0);
+		WifiManager wm = (WifiManager) appContext.getApplicationContext()
+				.getSystemService(WIFI_SERVICE);
+		if (wm != null) {
+			List<WifiConfiguration> configs = wm.getConfiguredNetworks();
+			if (configs != null) {
+				for (WifiConfiguration config : configs)
+					parcel.writeParcelable(config, 0);
+			}
 		}
 		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
 		if (bt != null) {
@@ -77,13 +81,13 @@ class AndroidSecureRandomProvider extends LinuxSecureRandomProvider {
 
 	// Based on https://android-developers.googleblog.com/2013/08/some-securerandom-thoughts.html
 	private void applyOpenSslFix() {
-		byte[] seed = new LinuxSecureRandomSpi().engineGenerateSeed(
+		byte[] seed = new UnixSecureRandomSpi().engineGenerateSeed(
 				SEED_LENGTH);
 		try {
 			// Seed the OpenSSL PRNG
 			Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
 					.getMethod("RAND_seed", byte[].class)
-					.invoke(null, seed);
+					.invoke(null, (Object) seed);
 			// Mix the output of the Linux PRNG into the OpenSSL PRNG
 			int bytesRead = (Integer) Class.forName(
 					"org.apache.harmony.xnet.provider.jsse.NativeCrypto")

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

@@ -208,6 +208,24 @@ public interface DatabaseComponent {
 	Collection<Message> generateRequestedBatch(Transaction txn, ContactId c,
 			int maxLength, int maxLatency) throws DbException;
 
+	/**
+	 * Returns the number of blocks in the given message.
+	 * <p>
+	 * Read-only.
+	 */
+	int getBlockCount(Transaction txn, MessageId m) throws DbException;
+
+	/**
+	 * Returns the given block of the given message.
+	 * <p>
+	 * Read-only.
+	 *
+	 * @throws NoSuchBlockException if 'blockNumber' is greater than or equal
+	 * to the number of blocks in the message
+	 */
+	byte[] getBlock(Transaction txn, MessageId m, int blockNumber)
+			throws DbException;
+
 	/**
 	 * Returns the contact with the given ID.
 	 * <p/>

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

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

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

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.api.io;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchBlockException;
+import org.briarproject.bramble.api.sync.MessageId;
+
+public interface BlockSource {
+
+	/**
+	 * Returns the number of blocks in the given message.
+	 */
+	int getBlockCount(MessageId m) throws DbException;
+
+	/**
+	 * Returns the given block of the given message.
+	 *
+	 * @throws NoSuchBlockException if 'blockNumber' is greater than or equal
+	 * to the number of blocks in the message
+	 */
+	byte[] getBlock(MessageId m, int blockNumber) throws DbException;
+}

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

@@ -0,0 +1,17 @@
+package org.briarproject.bramble.api.io;
+
+import org.briarproject.bramble.api.sync.MessageId;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public interface MessageInputStreamFactory {
+
+	/**
+	 * Returns an {@link InputStream} for reading the given message from the
+	 * database. This method returns immediately. If the message is not in the
+	 * database or cannot be read, reading from the stream will throw an
+	 * {@link IOException};
+	 */
+	InputStream getMessageInputStream(MessageId m);
+}

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

@@ -35,4 +35,9 @@ public interface SyncConstants {
 	 * The maximum number of message IDs in an ack, offer or request record.
 	 */
 	int MAX_MESSAGE_IDS = MAX_RECORD_PAYLOAD_BYTES / UniqueId.LENGTH;
+
+	/**
+	 * The maximum length of a message block in bytes.
+	 */
+	int MAX_BLOCK_LENGTH = 32 * 2014; // 32 KiB
 }

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

@@ -8,12 +8,15 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.net.ServerSocket;
 import java.net.Socket;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 public class IoUtils {
@@ -54,16 +57,35 @@ public class IoUtils {
 			out.flush();
 			out.close();
 		} catch (IOException e) {
-			tryToClose(in);
-			tryToClose(out);
+			tryToClose(in, LOG, WARNING);
+			tryToClose(out, LOG, WARNING);
 		}
 	}
 
-	private static void tryToClose(@Nullable Closeable c) {
+	public static void tryToClose(@Nullable Closeable c, Logger logger,
+			Level level) {
 		try {
 			if (c != null) c.close();
 		} catch (IOException e) {
-			// We did our best
+			logException(logger, level, e);
+		}
+	}
+
+	public static void tryToClose(@Nullable Socket s, Logger logger,
+			Level level) {
+		try {
+			if (s != null) s.close();
+		} catch (IOException e) {
+			logException(logger, level, e);
+		}
+	}
+
+	public static void tryToClose(@Nullable ServerSocket ss, Logger logger,
+			Level level) {
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			logException(logger, level, e);
 		}
 	}
 

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

@@ -10,8 +10,6 @@ public class OsUtils {
 	@Nullable
 	private static final String os = System.getProperty("os.name");
 	@Nullable
-	private static final String version = System.getProperty("os.version");
-	@Nullable
 	private static final String vendor = System.getProperty("java.vendor");
 
 	public static boolean isWindows() {

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

@@ -9,6 +9,7 @@ import org.briarproject.bramble.db.DatabaseExecutorModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.keyagreement.KeyAgreementModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.plugin.PluginModule;
@@ -36,6 +37,7 @@ import dagger.Module;
 		DatabaseExecutorModule.class,
 		EventModule.class,
 		IdentityModule.class,
+		IoModule.class,
 		KeyAgreementModule.class,
 		LifecycleModule.class,
 		PluginModule.class,

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

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.io.BlockSource;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import javax.inject.Inject;
+
+class BlockSourceImpl implements BlockSource {
+
+	private final DatabaseComponent db;
+
+	@Inject
+	BlockSourceImpl(DatabaseComponent db) {
+		this.db = db;
+	}
+
+	@Override
+	public int getBlockCount(MessageId m) throws DbException {
+		return db.transactionWithResult(true, txn -> db.getBlockCount(txn, m));
+	}
+
+	@Override
+	public byte[] getBlock(MessageId m, int blockNumber) throws DbException {
+		return db.transactionWithResult(true, txn ->
+				db.getBlock(txn, m, blockNumber));
+	}
+}

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

@@ -14,6 +14,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.DbRunnable;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
+import org.briarproject.bramble.api.db.NoSuchBlockException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.NoSuchGroupException;
 import org.briarproject.bramble.api.db.NoSuchLocalAuthorException;
@@ -420,6 +421,26 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return messages;
 	}
 
+	@Override
+	public int getBlockCount(Transaction transaction, MessageId m)
+			throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		return 1;
+	}
+
+	@Override
+	public byte[] getBlock(Transaction transaction, MessageId m,
+			int blockNumber) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		if (blockNumber != 0)
+			throw new NoSuchBlockException();
+		return db.getMessage(txn, m).getBody();
+	}
+
 	@Override
 	public Contact getContact(Transaction transaction, ContactId c)
 			throws DbException {

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.BlockSource;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
@@ -31,4 +32,9 @@ public class DatabaseModule {
 		return new DatabaseComponentImpl<>(db, Connection.class, eventBus,
 				shutdown);
 	}
+
+	@Provides
+	BlockSource provideBlockSource(BlockSourceImpl blockSource) {
+		return blockSource;
+	}
 }

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

@@ -15,16 +15,23 @@ import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.Properties;
+import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
 /**
  * Contains all the H2-specific code for the database.
  */
 @NotNullByDefault
 class H2Database extends JdbcDatabase {
 
+	private static final Logger LOG = getLogger(H2Database.class.getName());
+
 	private static final String HASH_TYPE = "BINARY(32)";
 	private static final String SECRET_TYPE = "BINARY(32)";
 	private static final String BINARY_TYPE = "BINARY";
@@ -121,8 +128,8 @@ class H2Database extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s);
-			tryToClose(c);
+			tryToClose(s, LOG, WARNING);
+			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}

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

@@ -14,16 +14,24 @@ import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.sql.Statement;
+import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
 /**
  * Contains all the HSQLDB-specific code for the database.
  */
 @NotNullByDefault
 class HyperSqlDatabase extends JdbcDatabase {
 
+	private static final Logger LOG =
+			getLogger(HyperSqlDatabase.class.getName());
+
 	private static final String HASH_TYPE = "BINARY(32)";
 	private static final String SECRET_TYPE = "BINARY(32)";
 	private static final String BINARY_TYPE = "BINARY";
@@ -72,8 +80,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s);
-			tryToClose(c);
+			tryToClose(s, LOG, WARNING);
+			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -122,8 +130,8 @@ class HyperSqlDatabase extends JdbcDatabase {
 			s.close();
 			c.close();
 		} catch (SQLException e) {
-			tryToClose(s);
-			tryToClose(c);
+			tryToClose(s, LOG, WARNING);
+			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}

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

@@ -72,6 +72,7 @@ import static org.briarproject.bramble.db.DatabaseConstants.LAST_COMPACTED_KEY;
 import static org.briarproject.bramble.db.DatabaseConstants.MAX_COMPACTION_INTERVAL_MS;
 import static org.briarproject.bramble.db.DatabaseConstants.SCHEMA_VERSION_KEY;
 import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -458,30 +459,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
 	}
 
-	private void tryToClose(@Nullable ResultSet rs) {
-		try {
-			if (rs != null) rs.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
-	protected void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
-	protected void tryToClose(@Nullable Connection c) {
-		try {
-			if (c != null) c.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private void createTables(Connection txn) throws DbException {
 		Statement s = null;
 		try {
@@ -502,7 +479,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_INCOMING_KEYS));
 			s.close();
 		} catch (SQLException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -519,7 +496,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP);
 			s.close();
 		} catch (SQLException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -566,11 +543,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		} catch (SQLException e) {
 			// Try to close the connection
 			logException(LOG, WARNING, e);
-			try {
-				txn.close();
-			} catch (SQLException e1) {
-				logException(LOG, WARNING, e1);
-			}
+			tryToClose(txn, LOG, WARNING);
 			// Whatever happens, allow the database to close
 			connectionsLock.lock();
 			try {
@@ -659,8 +632,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return c;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -681,7 +654,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -704,7 +677,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			// Create a status row for each message in the group
 			addStatus(txn, c, g, groupShared);
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -735,8 +708,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs.close();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -761,7 +734,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -810,7 +783,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -840,8 +813,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -873,7 +846,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -915,8 +888,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -935,7 +908,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1015,8 +988,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return keySetId;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1039,8 +1012,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1061,8 +1034,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1083,8 +1056,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1105,8 +1078,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1127,8 +1100,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1149,8 +1122,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1174,8 +1147,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return found;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1198,8 +1171,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return count;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1223,7 +1196,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1240,7 +1213,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1273,8 +1246,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			return new Contact(c, author, localAuthorId, alias, verified,
 					active);
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1310,8 +1283,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return contacts;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1333,8 +1306,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1371,8 +1344,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return contacts;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1395,8 +1368,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return new Group(g, clientId, majorVersion, descriptor);
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1423,8 +1396,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return groups;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1449,8 +1422,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return v;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1473,8 +1446,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return visible;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1505,8 +1478,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return localAuthor;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1537,8 +1510,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return authors;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1566,8 +1539,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			System.arraycopy(raw, MESSAGE_HEADER_LENGTH, body, 0, body.length);
 			return new Message(m, g, timestamp, body);
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1590,8 +1563,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1628,8 +1601,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (intersection == null) throw new AssertionError();
 			return intersection;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1661,8 +1634,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return all;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1696,8 +1669,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return metadata;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1720,8 +1693,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return metadata;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1746,8 +1719,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return metadata;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1776,8 +1749,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return statuses;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1807,8 +1780,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return status;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1837,8 +1810,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return dependencies;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1868,8 +1841,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return dependents;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1891,8 +1864,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return state;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1916,8 +1889,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1950,8 +1923,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -1975,8 +1948,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2014,8 +1987,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2048,8 +2021,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2076,8 +2049,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2106,8 +2079,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return nextSendTime;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2145,8 +2118,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return ids;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2168,8 +2141,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return s;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2234,8 +2207,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return keys;
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2254,7 +2227,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2281,7 +2254,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			}
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2308,7 +2281,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			}
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2338,7 +2311,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2383,8 +2356,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2450,7 +2423,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			}
 			return added;
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2497,7 +2470,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2516,7 +2489,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2535,7 +2508,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2554,7 +2527,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2571,7 +2544,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2587,7 +2560,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2615,7 +2588,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2632,7 +2605,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2648,7 +2621,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2667,7 +2640,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.close();
 			return affected == 1;
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2692,7 +2665,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2709,7 +2682,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2730,7 +2703,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2749,7 +2722,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2767,7 +2740,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2785,7 +2758,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2804,7 +2777,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2834,7 +2807,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2860,7 +2833,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2913,7 +2886,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2936,7 +2909,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2955,7 +2928,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -2991,8 +2964,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected != 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(rs);
-			tryToClose(ps);
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
@@ -3059,7 +3032,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (rows < 0 || rows > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
-			tryToClose(ps);
+			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}

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

@@ -0,0 +1,42 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+class JdbcUtils {
+
+	static void tryToClose(@Nullable ResultSet rs, Logger logger, Level level) {
+		try {
+			if (rs != null) rs.close();
+		} catch (SQLException e) {
+			logException(logger, level, e);
+		}
+	}
+
+	static void tryToClose(@Nullable Statement s, Logger logger, Level level) {
+		try {
+			if (s != null) s.close();
+		} catch (SQLException e) {
+			logException(logger, level, e);
+		}
+	}
+
+	static void tryToClose(@Nullable Connection c, Logger logger, Level level) {
+		try {
+			if (c != null) c.close();
+		} catch (SQLException e) {
+			logException(logger, level, e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration38_39.java

@@ -7,10 +7,8 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.logging.Logger;
 
-import javax.annotation.Nullable;
-
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
 
 class Migration38_39 implements Migration<Connection> {
 
@@ -40,16 +38,8 @@ class Migration38_39 implements Migration<Connection> {
 					+ " ALTER COLUMN contactId"
 					+ " SET NOT NULL");
 		} catch (SQLException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
-
-	private void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Migration39_40.java

@@ -7,10 +7,8 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.logging.Logger;
 
-import javax.annotation.Nullable;
-
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
 
 class Migration39_40 implements Migration<Connection> {
 
@@ -39,16 +37,8 @@ class Migration39_40 implements Migration<Connection> {
 					+ " ALTER COLUMN eta"
 					+ " SET NOT NULL");
 		} catch (SQLException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
-
-	private void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Migration40_41.java

@@ -7,11 +7,9 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.logging.Logger;
 
-import javax.annotation.Nullable;
-
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
 
 class Migration40_41 implements Migration<Connection> {
 
@@ -41,16 +39,8 @@ class Migration40_41 implements Migration<Connection> {
 			s.execute("ALTER TABLE contacts"
 					+ dbTypes.replaceTypes(" ADD alias _STRING"));
 		} catch (SQLException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}
-
-	private void tryToClose(@Nullable Statement s) {
-		try {
-			if (s != null) s.close();
-		} catch (SQLException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/io/BlockInputStream.java

@@ -0,0 +1,155 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InterruptedIOException;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.lang.System.arraycopy;
+import static java.lang.Thread.currentThread;
+
+/**
+ * An {@link InputStream} that asynchronously fetches blocks of data on demand.
+ */
+@ThreadSafe
+@NotNullByDefault
+abstract class BlockInputStream extends InputStream {
+
+	private final int minBufferBytes;
+	private final BlockingQueue<Buffer> queue = new ArrayBlockingQueue<>(1);
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	@Nullable
+	private Buffer buffer = null;
+
+	@GuardedBy("lock")
+	private int offset = 0;
+
+	@GuardedBy("lock")
+	private boolean fetchingBlock = false;
+
+	abstract void fetchBlockAsync(int blockNumber);
+
+	BlockInputStream(int minBufferBytes) {
+		this.minBufferBytes = minBufferBytes;
+	}
+
+	@Override
+	public int read() throws IOException {
+		synchronized (lock) {
+			if (!prepareRead()) return -1;
+			if (buffer == null) throw new AssertionError();
+			return buffer.data[offset++] & 0xFF;
+		}
+	}
+
+	@Override
+	public int read(byte[] b) throws IOException {
+		return read(b, 0, b.length);
+	}
+
+	@Override
+	public int read(byte[] b, int off, int len) throws IOException {
+		if (off < 0 || len < 0 || off + len > b.length)
+			throw new IllegalArgumentException();
+		synchronized (lock) {
+			if (!prepareRead()) return -1;
+			if (buffer == null) throw new AssertionError();
+			len = Math.min(len, buffer.length - offset);
+			if (len < 0) throw new AssertionError();
+			arraycopy(buffer.data, offset, b, off, len);
+			offset += len;
+			return len;
+		}
+	}
+
+	private boolean prepareRead() throws IOException {
+		throwExceptionIfNecessary();
+		if (isEndOfStream()) return false;
+		if (shouldFetchBlock()) fetchBlockAsync();
+		waitForBlock();
+		if (buffer == null) throw new AssertionError();
+		return offset < buffer.length;
+	}
+
+	@GuardedBy("lock")
+	private void throwExceptionIfNecessary() throws IOException {
+		if (buffer != null && buffer.exception != null)
+			throw new IOException(buffer.exception);
+	}
+
+	@GuardedBy("lock")
+	private boolean isEndOfStream() {
+		return buffer != null && offset == buffer.length && !fetchingBlock;
+	}
+
+	@GuardedBy("lock")
+	private boolean shouldFetchBlock() {
+		if (fetchingBlock) return false;
+		if (buffer == null) return true;
+		if (buffer.length == 0) return false;
+		return buffer.length - offset < minBufferBytes;
+	}
+
+	@GuardedBy("lock")
+	private void fetchBlockAsync() {
+		if (buffer == null) fetchBlockAsync(0);
+		else fetchBlockAsync(buffer.blockNumber + 1);
+		fetchingBlock = true;
+	}
+
+	@GuardedBy("lock")
+	private void waitForBlock() throws IOException {
+		if (buffer != null && offset < buffer.length) return;
+		try {
+			buffer = queue.take();
+		} catch (InterruptedException e) {
+			currentThread().interrupt();
+			throw new InterruptedIOException();
+		}
+		fetchingBlock = false;
+		offset = 0;
+		throwExceptionIfNecessary();
+	}
+
+	void fetchSucceeded(int blockNumber, byte[] data, int length) {
+		queue.add(new Buffer(blockNumber, data, length));
+	}
+
+	void fetchFailed(int blockNumber, Exception exception) {
+		queue.add(new Buffer(blockNumber, exception));
+	}
+
+	private static class Buffer {
+
+		private final int blockNumber;
+		private final byte[] data;
+		private final int length;
+		@Nullable
+		private final Exception exception;
+
+		private Buffer(int blockNumber, byte[] data, int length) {
+			if (length < 0 || length > data.length)
+				throw new IllegalArgumentException();
+			this.blockNumber = blockNumber;
+			this.data = data;
+			this.length = length;
+			exception = null;
+		}
+
+		private Buffer(int blockNumber, Exception exception) {
+			this.blockNumber = blockNumber;
+			this.exception = exception;
+			data = new byte[0];
+			length = 0;
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/io/BlockSourceInputStream.java

@@ -0,0 +1,53 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.io.BlockSource;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+/**
+ * A {@link BlockInputStream} that fetches data from a {@link BlockSource}.
+ */
+@ThreadSafe
+@NotNullByDefault
+class BlockSourceInputStream extends BlockInputStream {
+
+	private final Executor executor;
+	private final BlockSource blockSource;
+	private final MessageId messageId;
+
+	private volatile int blockCount = -1;
+
+	BlockSourceInputStream(int minBufferBytes, Executor executor,
+			BlockSource blockSource, MessageId messageId) {
+		super(minBufferBytes);
+		this.executor = executor;
+		this.blockSource = blockSource;
+		this.messageId = messageId;
+	}
+
+	@Override
+	void fetchBlockAsync(int blockNumber) {
+		executor.execute(() -> {
+			try {
+				if (blockCount == -1) {
+					blockCount = blockSource.getBlockCount(messageId);
+				}
+				if (blockNumber > blockCount) {
+					fetchFailed(blockNumber, new IllegalArgumentException());
+				} else if (blockNumber == blockCount) {
+					fetchSucceeded(blockNumber, new byte[0], 0); // EOF
+				} else {
+					byte[] block = blockSource.getBlock(messageId, blockNumber);
+					fetchSucceeded(blockNumber, block, block.length);
+				}
+			} catch (DbException e) {
+				fetchFailed(blockNumber, e);
+			}
+		});
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/io/IoModule.java

@@ -0,0 +1,16 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.io.MessageInputStreamFactory;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class IoModule {
+
+	@Provides
+	MessageInputStreamFactory provideMessageInputStreamFactory(
+			MessageInputStreamFactoryImpl messageInputStreamFactory) {
+		return messageInputStreamFactory;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/io/MessageInputStreamFactoryImpl.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.io.BlockSource;
+import org.briarproject.bramble.api.io.MessageInputStreamFactory;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import java.io.InputStream;
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_BLOCK_LENGTH;
+
+class MessageInputStreamFactoryImpl implements MessageInputStreamFactory {
+
+	private final Executor dbExecutor;
+	private final BlockSource blockSource;
+
+	@Inject
+	MessageInputStreamFactoryImpl(@DatabaseExecutor Executor dbExecutor,
+			BlockSource blockSource) {
+		this.dbExecutor = dbExecutor;
+		this.blockSource = blockSource;
+	}
+
+	@Override
+	public InputStream getMessageInputStream(MessageId m) {
+		return new BlockSourceInputStream(MAX_BLOCK_LENGTH, dbExecutor,
+				blockSource, m);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FileTransportReader.java

@@ -4,12 +4,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 
 import java.io.File;
-import java.io.IOException;
 import java.io.InputStream;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
 
 @NotNullByDefault
 class FileTransportReader implements TransportConnectionReader {
@@ -34,11 +33,7 @@ class FileTransportReader implements TransportConnectionReader {
 
 	@Override
 	public void dispose(boolean exception, boolean recognised) {
-		try {
-			in.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
+		tryToClose(in, LOG, WARNING);
 		plugin.readerFinished(file, exception, recognised);
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FileTransportWriter.java

@@ -4,12 +4,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 
 import java.io.File;
-import java.io.IOException;
 import java.io.OutputStream;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
 
 @NotNullByDefault
 class FileTransportWriter implements TransportConnectionWriter {
@@ -44,11 +43,7 @@ class FileTransportWriter implements TransportConnectionWriter {
 
 	@Override
 	public void dispose(boolean exception) {
-		try {
-			out.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
+		tryToClose(out, LOG, WARNING);
 		plugin.writerFinished(file, exception);
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
@@ -35,7 +36,6 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PREF_LAN_IP_PORTS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PROP_IP_PORTS;
 import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 
 @NotNullByDefault
@@ -293,11 +293,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 		@Override
 		public void close() {
-			try {
-				ss.close();
-			} catch (IOException e) {
-				logException(LOG, WARNING, e);
-			}
+			IoUtils.tryToClose(ss, LOG, WARNING);
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
@@ -153,13 +154,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 
 	protected void tryToClose(@Nullable ServerSocket ss) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		} finally {
-			callback.transportDisabled();
-		}
+		IoUtils.tryToClose(ss, LOG, WARNING);
+		callback.transportDisabled();
 	}
 
 	String getIpPortString(InetSocketAddress a) {

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -31,7 +31,6 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 import org.briarproject.bramble.util.IoUtils;
 
-import java.io.Closeable;
 import java.io.EOFException;
 import java.io.File;
 import java.io.FileInputStream;
@@ -303,8 +302,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			IoUtils.copyAndClose(in, out);
 			doneFile.createNewFile();
 		} catch (IOException e) {
-			tryToClose(in);
-			tryToClose(out);
+			IoUtils.tryToClose(in, LOG, WARNING);
+			IoUtils.tryToClose(out, LOG, WARNING);
 			throw new PluginException(e);
 		}
 	}
@@ -341,22 +340,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		return getClass().getClassLoader().getResourceAsStream("torrc");
 	}
 
-	private void tryToClose(@Nullable Closeable c) {
-		try {
-			if (c != null) c.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
-	private void tryToClose(@Nullable Socket s) {
-		try {
-			if (s != null) s.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private void listFiles(File f) {
 		if (f.isDirectory()) {
 			File[] children = f.listFiles();
@@ -378,7 +361,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			}
 			return b;
 		} finally {
-			tryToClose(in);
+			IoUtils.tryToClose(in, LOG, WARNING);
 		}
 	}
 
@@ -418,13 +401,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void tryToClose(@Nullable ServerSocket ss) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		} finally {
-			callback.transportDisabled();
-		}
+		IoUtils.tryToClose(ss, LOG, WARNING);
+		callback.transportDisabled();
 	}
 
 	private void publishHiddenService(String port) {
@@ -593,7 +571,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				LOG.info("Could not connect to " + scrubOnion(bestOnion)
 						+ ": " + e.toString());
 			}
-			tryToClose(s);
+			IoUtils.tryToClose(s, LOG, WARNING);
 			return null;
 		}
 	}

bramble-core/src/main/java/org/briarproject/bramble/reporting/DevReporterImpl.java

@@ -12,7 +12,6 @@ import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.IoUtils;
 import org.briarproject.bramble.util.StringUtils;
 
-import java.io.Closeable;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -26,13 +25,12 @@ import java.net.Socket;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
 
 @Immutable
 @NotNullByDefault
@@ -66,7 +64,7 @@ class DevReporterImpl implements DevReporter, EventListener {
 			s.setSoTimeout(SOCKET_TIMEOUT);
 			return s;
 		} catch (IOException e) {
-			tryToClose(s);
+			tryToClose(s, LOG, WARNING);
 			throw e;
 		}
 	}
@@ -88,8 +86,7 @@ class DevReporterImpl implements DevReporter, EventListener {
 			writer.append(armoured);
 			writer.flush();
 		} finally {
-			if (writer != null)
-				writer.close();
+			tryToClose(writer, LOG, WARNING);
 		}
 	}
 
@@ -121,27 +118,11 @@ class DevReporterImpl implements DevReporter, EventListener {
 				f.delete();
 			} catch (IOException e) {
 				LOG.log(WARNING, "Failed to send reports", e);
-				tryToClose(out);
-				tryToClose(in);
+				tryToClose(out, LOG, WARNING);
+				tryToClose(in, LOG, WARNING);
 				return;
 			}
 		}
 		LOG.info("Reports sent");
 	}
-
-	private void tryToClose(@Nullable Closeable c) {
-		try {
-			if (c != null) c.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
-	private void tryToClose(@Nullable Socket s) {
-		try {
-			if (s != null) s.close();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/system/UnixSecureRandomProvider.java

@@ -13,32 +13,33 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.Immutable;
 
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @Immutable
 @NotNullByDefault
-class LinuxSecureRandomProvider extends AbstractSecureRandomProvider {
+class UnixSecureRandomProvider extends AbstractSecureRandomProvider {
 
 	private static final Logger LOG =
-			Logger.getLogger(LinuxSecureRandomProvider.class.getName());
+			getLogger(UnixSecureRandomProvider.class.getName());
 
 	private static final File RANDOM_DEVICE = new File("/dev/urandom");
 
 	private final AtomicBoolean seeded = new AtomicBoolean(false);
 	private final File outputDevice;
 
-	LinuxSecureRandomProvider() {
+	UnixSecureRandomProvider() {
 		this(RANDOM_DEVICE);
 	}
 
-	LinuxSecureRandomProvider(File outputDevice) {
+	UnixSecureRandomProvider(File outputDevice) {
 		this.outputDevice = outputDevice;
 	}
 
 	@Override
 	public Provider getProvider() {
 		if (!seeded.getAndSet(true)) writeSeed();
-		return new LinuxProvider();
+		return new UnixProvider();
 	}
 
 	protected void writeSeed() {
@@ -55,15 +56,15 @@ class LinuxSecureRandomProvider extends AbstractSecureRandomProvider {
 	}
 
 	// Based on https://android-developers.googleblog.com/2013/08/some-securerandom-thoughts.html
-	private static class LinuxProvider extends Provider {
+	private static class UnixProvider extends Provider {
 
-		private LinuxProvider() {
-			super("LinuxPRNG", 1.1, "A Linux-specific PRNG using /dev/urandom");
+		private UnixProvider() {
+			super("UnixPRNG", 1.0, "A Unix-specific PRNG using /dev/urandom");
 			// Although /dev/urandom is not a SHA-1 PRNG, some callers
 			// explicitly request a SHA1PRNG SecureRandom and we need to
 			// prevent them from getting the default implementation whose
 			// output may have low entropy.
-			put("SecureRandom.SHA1PRNG", LinuxSecureRandomSpi.class.getName());
+			put("SecureRandom.SHA1PRNG", UnixSecureRandomSpi.class.getName());
 			put("SecureRandom.SHA1PRNG ImplementedIn", "Software");
 		}
 	}

bramble-core/src/main/java/org/briarproject/bramble/system/UnixSecureRandomSpi.java

@@ -10,22 +10,24 @@ import java.security.SecureRandomSpi;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
-public class LinuxSecureRandomSpi extends SecureRandomSpi {
+public class UnixSecureRandomSpi extends SecureRandomSpi {
 
 	private static final Logger LOG =
-			Logger.getLogger(LinuxSecureRandomSpi.class.getName());
+			getLogger(UnixSecureRandomSpi.class.getName());
 
 	private static final File RANDOM_DEVICE = new File("/dev/urandom");
 
 	private final File inputDevice, outputDevice;
 
-	public LinuxSecureRandomSpi() {
+	@SuppressWarnings("WeakerAccess")
+	public UnixSecureRandomSpi() {
 		this(RANDOM_DEVICE, RANDOM_DEVICE);
 	}
 
-	LinuxSecureRandomSpi(File inputDevice, File outputDevice) {
+	UnixSecureRandomSpi(File inputDevice, File outputDevice) {
 		this.inputDevice = inputDevice;
 		this.outputDevice = outputDevice;
 	}

bramble-core/src/test/java/org/briarproject/bramble/io/BlockSourceInputStreamTest.java

@@ -0,0 +1,151 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.io.BlockSource;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.jmock.Expectations;
+import org.jmock.lib.concurrent.Synchroniser;
+import org.junit.Test;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Random;
+import java.util.concurrent.Executor;
+
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_BLOCK_LENGTH;
+import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.spongycastle.util.Arrays.copyOfRange;
+
+public class BlockSourceInputStreamTest extends BrambleMockTestCase {
+
+	private static final int MAX_DATA_BYTES = 1_000_000;
+	private static final int READ_BUFFER_BYTES = 4 * 1024;
+
+	private final BlockSource blockSource;
+
+	private final Random random = new Random();
+	private final Executor executor = newSingleThreadExecutor();
+	private final MessageId messageId = new MessageId(getRandomId());
+
+	public BlockSourceInputStreamTest() {
+		context.setThreadingPolicy(new Synchroniser());
+		blockSource = context.mock(BlockSource.class);
+	}
+
+	@Test
+	public void testReadSingleBytes() throws IOException {
+		byte[] data = createRandomData();
+		BlockSource source = new ByteArrayBlockSource(data, MAX_BLOCK_LENGTH);
+		InputStream in = new BlockSourceInputStream(MAX_BLOCK_LENGTH, executor,
+				source, messageId);
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		//noinspection ForLoopReplaceableByForEach
+		for (int i = 0; i < data.length; i++) {
+			int read = in.read();
+			assertNotEquals(-1, read);
+			out.write(read);
+		}
+		assertEquals(-1, in.read());
+		in.close();
+		out.flush();
+		out.close();
+		assertArrayEquals(data, out.toByteArray());
+	}
+
+	@Test
+	public void testReadByteArrays() throws IOException {
+		byte[] data = createRandomData();
+		BlockSource source = new ByteArrayBlockSource(data, MAX_BLOCK_LENGTH);
+		InputStream in = new BlockSourceInputStream(MAX_BLOCK_LENGTH, executor,
+				source, messageId);
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		byte[] buf = new byte[READ_BUFFER_BYTES];
+		int dataOffset = 0;
+		while (dataOffset < data.length) {
+			int length = Math.min(random.nextInt(buf.length) + 1,
+					data.length - dataOffset);
+			int bufOffset = 0;
+			if (length < buf.length)
+				bufOffset = random.nextInt(buf.length - length);
+			int read = in.read(buf, bufOffset, length);
+			assertNotEquals(-1, read);
+			out.write(buf, bufOffset, read);
+			dataOffset += read;
+		}
+		assertEquals(-1, in.read(buf, 0, 0));
+		in.close();
+		out.flush();
+		out.close();
+		assertArrayEquals(data, out.toByteArray());
+	}
+
+	@Test(expected = IOException.class)
+	public void testDbExceptionFromGetBlockCountIsRethrown() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(blockSource).getBlockCount(messageId);
+			will(throwException(new DbException()));
+		}});
+
+		InputStream in = new BlockSourceInputStream(MAX_BLOCK_LENGTH, executor,
+				blockSource, messageId);
+		//noinspection ResultOfMethodCallIgnored
+		in.read();
+	}
+
+	@Test(expected = IOException.class)
+	public void testDbExceptionFromGetBlockIsRethrown() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(blockSource).getBlockCount(messageId);
+			will(returnValue(1));
+			oneOf(blockSource).getBlock(messageId, 0);
+			will(throwException(new DbException()));
+		}});
+
+		InputStream in = new BlockSourceInputStream(MAX_BLOCK_LENGTH, executor,
+				blockSource, messageId);
+		//noinspection ResultOfMethodCallIgnored
+		in.read();
+	}
+
+	@Test
+	public void testReadFullBlockAtEndOfMessage() throws Exception {
+		testReadBlockAtEndOfMessage(MAX_BLOCK_LENGTH);
+	}
+
+	@Test
+	public void testReadPartialBlockAtEndOfMessage() throws Exception {
+		testReadBlockAtEndOfMessage(MAX_BLOCK_LENGTH - 1);
+	}
+
+	private void testReadBlockAtEndOfMessage(int blockLength) throws Exception {
+		byte[] block = new byte[blockLength];
+		random.nextBytes(block);
+
+		context.checking(new Expectations() {{
+			oneOf(blockSource).getBlockCount(messageId);
+			will(returnValue(1));
+			oneOf(blockSource).getBlock(messageId, 0);
+			will(returnValue(block));
+		}});
+
+		InputStream in = new BlockSourceInputStream(MAX_BLOCK_LENGTH, executor,
+				blockSource, messageId);
+		byte[] buf = new byte[MAX_BLOCK_LENGTH * 2];
+		assertEquals(block.length, in.read(buf, 0, buf.length));
+		assertArrayEquals(block, copyOfRange(buf, 0, block.length));
+		assertEquals(-1, in.read(buf, 0, buf.length));
+	}
+
+	private byte[] createRandomData() {
+		int length = random.nextInt(MAX_DATA_BYTES) + 1;
+		byte[] data = new byte[length];
+		random.nextBytes(data);
+		return data;
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/io/ByteArrayBlockSource.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.io.BlockSource;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import static java.lang.System.arraycopy;
+
+class ByteArrayBlockSource implements BlockSource {
+
+	private final byte[] data;
+	private final int blockBytes;
+
+	ByteArrayBlockSource(byte[] data, int blockBytes) {
+		this.data = data;
+		this.blockBytes = blockBytes;
+	}
+
+	@Override
+	public int getBlockCount(MessageId m) {
+		return (data.length + blockBytes - 1) / blockBytes;
+	}
+
+	@Override
+	public byte[] getBlock(MessageId m, int blockNumber) {
+		int offset = blockNumber * blockBytes;
+		if (offset >= data.length) throw new IllegalArgumentException();
+		int length = Math.min(blockBytes, data.length - offset);
+		byte[] block = new byte[length];
+		arraycopy(data, offset, block, 0, length);
+		return block;
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/system/UnixSecureRandomProviderTest.java

@@ -1,8 +1,6 @@
 package org.briarproject.bramble.system;
 
 import org.briarproject.bramble.test.BrambleTestCase;
-import org.briarproject.bramble.test.TestUtils;
-import org.briarproject.bramble.util.OsUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -10,48 +8,50 @@ import org.junit.Test;
 import java.io.File;
 import java.security.Provider;
 
+import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
+import static org.briarproject.bramble.test.TestUtils.getTestDirectory;
+import static org.briarproject.bramble.util.OsUtils.isLinux;
+import static org.briarproject.bramble.util.OsUtils.isMac;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 
-public class LinuxSecureRandomProviderTest extends BrambleTestCase {
+public class UnixSecureRandomProviderTest extends BrambleTestCase {
 
-	private final File testDir = TestUtils.getTestDirectory();
+	private final File testDir = getTestDirectory();
 
 	@Before
 	public void setUp() {
-		testDir.mkdirs();
+		assumeTrue(isLinux() || isMac());
+		assertTrue(testDir.mkdirs());
 	}
 
 	@Test
 	public void testGetProviderWritesToRandomDeviceOnFirstCall()
 			throws Exception {
-		if (!(OsUtils.isLinux())) {
-			System.err.println("WARNING: Skipping test, can't run on this OS");
-			return;
-		}
 		// Redirect the provider's output to a file
 		File urandom = new File(testDir, "urandom");
-		urandom.delete();
+		if (urandom.exists()) assertTrue(urandom.delete());
 		assertTrue(urandom.createNewFile());
 		assertEquals(0, urandom.length());
-		LinuxSecureRandomProvider p = new LinuxSecureRandomProvider(urandom);
+		UnixSecureRandomProvider p = new UnixSecureRandomProvider(urandom);
 		// Getting a provider should write entropy to the file
 		Provider provider = p.getProvider();
 		assertNotNull(provider);
-		assertEquals("LinuxPRNG", provider.getName());
+		assertEquals("UnixPRNG", provider.getName());
 		// There should be at least 16 bytes from the clock, 8 from the runtime
 		long length = urandom.length();
 		assertTrue(length >= 24);
 		// Getting another provider should not write to the file again
 		provider = p.getProvider();
 		assertNotNull(provider);
-		assertEquals("LinuxPRNG", provider.getName());
+		assertEquals("UnixPRNG", provider.getName());
 		assertEquals(length, urandom.length());
 	}
 
 	@After
 	public void tearDown() {
-		TestUtils.deleteTestDirectory(testDir);
+		deleteTestDirectory(testDir);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/system/UnixSecureRandomSpiTest.java

@@ -4,7 +4,6 @@ import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestUtils;
 import org.briarproject.bramble.util.IoUtils;
-import org.briarproject.bramble.util.OsUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -15,31 +14,33 @@ import java.io.FileOutputStream;
 import java.util.HashSet;
 import java.util.Set;
 
+import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
+import static org.briarproject.bramble.test.TestUtils.getTestDirectory;
+import static org.briarproject.bramble.util.OsUtils.isLinux;
+import static org.briarproject.bramble.util.OsUtils.isMac;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 
 
-public class LinuxSecureRandomSpiTest extends BrambleTestCase {
+public class UnixSecureRandomSpiTest extends BrambleTestCase {
 
 	private static final File RANDOM_DEVICE = new File("/dev/urandom");
 	private static final int SEED_BYTES = 32;
 
-	private final File testDir = TestUtils.getTestDirectory();
+	private final File testDir = getTestDirectory();
 
 	@Before
 	public void setUp() {
-		testDir.mkdirs();
+		assumeTrue(isLinux() || isMac());
+		assertTrue(testDir.mkdirs());
 	}
 
 	@Test
 	public void testSeedsAreDistinct() {
-		if (!(OsUtils.isLinux())) {
-			System.err.println("WARNING: Skipping test, can't run on this OS");
-			return;
-		}
 		Set<Bytes> seeds = new HashSet<>();
-		LinuxSecureRandomSpi engine = new LinuxSecureRandomSpi();
+		UnixSecureRandomSpi engine = new UnixSecureRandomSpi();
 		for (int i = 0; i < 1000; i++) {
 			byte[] seed = engine.engineGenerateSeed(SEED_BYTES);
 			assertEquals(SEED_BYTES, seed.length);
@@ -49,19 +50,15 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 
 	@Test
 	public void testEngineSetSeedWritesToRandomDevice() throws Exception {
-		if (!(OsUtils.isLinux())) {
-			System.err.println("WARNING: Skipping test, can't run on this OS");
-			return;
-		}
 		// Redirect the engine's output to a file
 		File urandom = new File(testDir, "urandom");
-		urandom.delete();
+		if (urandom.exists()) assertTrue(urandom.delete());
 		assertTrue(urandom.createNewFile());
 		assertEquals(0, urandom.length());
 		// Generate a seed
 		byte[] seed = TestUtils.getRandomBytes(SEED_BYTES);
 		// Check that the engine writes the seed to the file
-		LinuxSecureRandomSpi engine = new LinuxSecureRandomSpi(RANDOM_DEVICE,
+		UnixSecureRandomSpi engine = new UnixSecureRandomSpi(RANDOM_DEVICE,
 				urandom);
 		engine.engineSetSeed(seed);
 		assertEquals(SEED_BYTES, urandom.length());
@@ -74,15 +71,11 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 
 	@Test
 	public void testEngineNextBytesReadsFromRandomDevice() throws Exception {
-		if (!(OsUtils.isLinux())) {
-			System.err.println("WARNING: Skipping test, can't run on this OS");
-			return;
-		}
 		// Generate some entropy
 		byte[] entropy = TestUtils.getRandomBytes(SEED_BYTES);
 		// Write the entropy to a file
 		File urandom = new File(testDir, "urandom");
-		urandom.delete();
+		if (urandom.exists()) assertTrue(urandom.delete());
 		FileOutputStream out = new FileOutputStream(urandom);
 		out.write(entropy);
 		out.flush();
@@ -90,7 +83,7 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 		assertTrue(urandom.exists());
 		assertEquals(SEED_BYTES, urandom.length());
 		// Check that the engine reads from the file
-		LinuxSecureRandomSpi engine = new LinuxSecureRandomSpi(urandom,
+		UnixSecureRandomSpi engine = new UnixSecureRandomSpi(urandom,
 				RANDOM_DEVICE);
 		byte[] b = new byte[SEED_BYTES];
 		engine.engineNextBytes(b);
@@ -99,15 +92,11 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 
 	@Test
 	public void testEngineGenerateSeedReadsFromRandomDevice() throws Exception {
-		if (!(OsUtils.isLinux())) {
-			System.err.println("WARNING: Skipping test, can't run on this OS");
-			return;
-		}
 		// Generate some entropy
 		byte[] entropy = TestUtils.getRandomBytes(SEED_BYTES);
 		// Write the entropy to a file
 		File urandom = new File(testDir, "urandom");
-		urandom.delete();
+		if (urandom.exists()) assertTrue(urandom.delete());
 		FileOutputStream out = new FileOutputStream(urandom);
 		out.write(entropy);
 		out.flush();
@@ -115,7 +104,7 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 		assertTrue(urandom.exists());
 		assertEquals(SEED_BYTES, urandom.length());
 		// Check that the engine reads from the file
-		LinuxSecureRandomSpi engine = new LinuxSecureRandomSpi(urandom,
+		UnixSecureRandomSpi engine = new UnixSecureRandomSpi(urandom,
 				RANDOM_DEVICE);
 		byte[] b = engine.engineGenerateSeed(SEED_BYTES);
 		assertArrayEquals(entropy, b);
@@ -123,6 +112,6 @@ public class LinuxSecureRandomSpiTest extends BrambleTestCase {
 
 	@After
 	public void tearDown() {
-		TestUtils.deleteTestDirectory(testDir);
+		deleteTestDirectory(testDir);
 	}
 }

bramble-java/src/main/java/org/briarproject/bramble/lifecycle/DesktopLifecycleModule.java

@@ -1,20 +1,21 @@
 package org.briarproject.bramble.lifecycle;
 
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
-import org.briarproject.bramble.util.OsUtils;
 
 import javax.inject.Singleton;
 
 import dagger.Module;
 import dagger.Provides;
 
+import static org.briarproject.bramble.util.OsUtils.isWindows;
+
 @Module
 public class DesktopLifecycleModule extends LifecycleModule {
 
 	@Provides
 	@Singleton
 	ShutdownManager provideDesktopShutdownManager() {
-		if (OsUtils.isWindows()) return new WindowsShutdownManagerImpl();
+		if (isWindows()) return new WindowsShutdownManagerImpl();
 		else return new ShutdownManagerImpl();
 	}
 }

bramble-java/src/main/java/org/briarproject/bramble/lifecycle/WindowsShutdownManagerImpl.java

@@ -15,7 +15,6 @@ import com.sun.jna.win32.W32APIFunctionMapper;
 import com.sun.jna.win32.W32APITypeMapper;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.util.OsUtils;
 
 import java.util.Collections;
 import java.util.HashMap;
@@ -29,6 +28,7 @@ import static com.sun.jna.Library.OPTION_FUNCTION_MAPPER;
 import static com.sun.jna.Library.OPTION_TYPE_MAPPER;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.OsUtils.isWindows;
 
 @ThreadSafe
 @NotNullByDefault
@@ -71,7 +71,7 @@ class WindowsShutdownManagerImpl extends ShutdownManagerImpl {
 
 	// Locking: lock
 	private void initialise() {
-		if (OsUtils.isWindows()) {
+		if (isWindows()) {
 			new EventLoop().start();
 		} else {
 			LOG.warning("Windows shutdown manager used on non-Windows OS");
@@ -111,7 +111,7 @@ class WindowsShutdownManagerImpl extends ShutdownManagerImpl {
 		public void run() {
 			try {
 				// Load user32.dll
-				User32 user32 = (User32) Native.loadLibrary("user32",
+				User32 user32 = Native.loadLibrary("user32",
 						User32.class, options);
 				// Create a callback to handle the WM_QUERYENDSESSION message
 				WindowProc proc = (hwnd, msg, wp, lp) -> {

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/JavaTorPlugin.java

@@ -10,7 +10,6 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 
 import java.io.File;
-import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.security.CodeSource;
@@ -19,9 +18,9 @@ import java.util.concurrent.Executor;
 import javax.net.SocketFactory;
 
 @NotNullByDefault
-class LinuxTorPlugin extends TorPlugin {
+abstract class JavaTorPlugin extends TorPlugin {
 
-	LinuxTorPlugin(Executor ioExecutor, NetworkManager networkManager,
+	JavaTorPlugin(Executor ioExecutor, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
@@ -34,17 +33,6 @@ class LinuxTorPlugin extends TorPlugin {
 				torDirectory);
 	}
 
-	@Override
-	protected int getProcessId() {
-		try {
-			// Java 9: ProcessHandle.current().pid()
-			return Integer.parseInt(
-					new File("/proc/self").getCanonicalFile().getName());
-		} catch (IOException e) {
-			throw new AssertionError(e);
-		}
-	}
-
 	@Override
 	protected long getLastUpdateTime() {
 		CodeSource codeSource =
@@ -58,5 +46,4 @@ class LinuxTorPlugin extends TorPlugin {
 			throw new AssertionError(e);
 		}
 	}
-
 }

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/UnixTorPlugin.java

@@ -0,0 +1,47 @@
+package org.briarproject.bramble.plugin.tor;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+
+import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.network.NetworkManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.api.system.ResourceProvider;
+
+import java.io.File;
+import java.util.concurrent.Executor;
+
+import javax.net.SocketFactory;
+
+@NotNullByDefault
+class UnixTorPlugin extends JavaTorPlugin {
+
+	UnixTorPlugin(Executor ioExecutor, NetworkManager networkManager,
+			LocationUtils locationUtils, SocketFactory torSocketFactory,
+			Clock clock, ResourceProvider resourceProvider,
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Backoff backoff,
+			DuplexPluginCallback callback, String architecture, int maxLatency,
+			int maxIdleTime, File torDirectory) {
+		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
+				clock, resourceProvider, circumventionProvider, batteryManager,
+				backoff, callback, architecture, maxLatency, maxIdleTime,
+				torDirectory);
+	}
+
+	@Override
+	protected int getProcessId() {
+		return CLibrary.INSTANCE.getpid();
+	}
+
+	private interface CLibrary extends Library {
+
+		CLibrary INSTANCE = (CLibrary) Native.loadLibrary("c", CLibrary.class);
+
+		int getpid();
+	}
+}

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/UnixTorPluginFactory.java

@@ -22,14 +22,15 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.Immutable;
 import javax.net.SocketFactory;
 
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.OsUtils.isLinux;
 
 @Immutable
 @NotNullByDefault
-public class LinuxTorPluginFactory implements DuplexPluginFactory {
+public class UnixTorPluginFactory implements DuplexPluginFactory {
 
 	private static final Logger LOG =
-			Logger.getLogger(LinuxTorPluginFactory.class.getName());
+			getLogger(UnixTorPluginFactory.class.getName());
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
 	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
@@ -49,7 +50,7 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 	private final Clock clock;
 	private final File torDirectory;
 
-	public LinuxTorPluginFactory(Executor ioExecutor,
+	public UnixTorPluginFactory(Executor ioExecutor,
 			NetworkManager networkManager, LocationUtils locationUtils,
 			EventBus eventBus, SocketFactory torSocketFactory,
 			BackoffFactory backoffFactory, ResourceProvider resourceProvider,
@@ -95,7 +96,7 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		LinuxTorPlugin plugin = new LinuxTorPlugin(ioExecutor, networkManager,
+		UnixTorPlugin plugin = new UnixTorPlugin(ioExecutor, networkManager,
 				locationUtils, torSocketFactory, clock, resourceProvider,
 				circumventionProvider, batteryManager, backoff, callback,
 				architecture, MAX_LATENCY, MAX_IDLE_TIME, torDirectory);

bramble-java/src/main/java/org/briarproject/bramble/system/DesktopSecureRandomModule.java

@@ -1,19 +1,24 @@
 package org.briarproject.bramble.system;
 
 import org.briarproject.bramble.api.system.SecureRandomProvider;
-import org.briarproject.bramble.util.OsUtils;
 
 import javax.inject.Singleton;
 
 import dagger.Module;
 import dagger.Provides;
 
+import static org.briarproject.bramble.util.OsUtils.isLinux;
+import static org.briarproject.bramble.util.OsUtils.isMac;
+
 @Module
 public class DesktopSecureRandomModule {
 
 	@Provides
 	@Singleton
 	SecureRandomProvider provideSecureRandomProvider() {
-		return OsUtils.isLinux() ? new LinuxSecureRandomProvider() : null;
+		if (isLinux() || isMac())
+			return new UnixSecureRandomProvider();
+		// TODO: Create a secure random provider for Windows
+		throw new UnsupportedOperationException();
 	}
 }

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

@@ -70,7 +70,7 @@ public class BridgeTest extends BrambleTestCase {
 	private final File torDir = getTestDirectory();
 	private final String bridge;
 
-	private LinuxTorPluginFactory factory;
+	private UnixTorPluginFactory factory;
 
 	public BridgeTest(String bridge) {
 		this.bridge = bridge;
@@ -108,7 +108,7 @@ public class BridgeTest extends BrambleTestCase {
 				return singletonList(bridge);
 			}
 		};
-		factory = new LinuxTorPluginFactory(ioExecutor, networkManager,
+		factory = new UnixTorPluginFactory(ioExecutor, networkManager,
 				locationUtils, eventBus, torSocketFactory, backoffFactory,
 				resourceProvider, bridgeProvider, batteryManager, clock,
 				torDir);
@@ -124,7 +124,7 @@ public class BridgeTest extends BrambleTestCase {
 		DuplexPlugin duplexPlugin =
 				factory.createPlugin(new TorPluginCallBack());
 		assertNotNull(duplexPlugin);
-		LinuxTorPlugin plugin = (LinuxTorPlugin) duplexPlugin;
+		UnixTorPlugin plugin = (UnixTorPlugin) duplexPlugin;
 
 		LOG.warning("Testing " + bridge);
 		try {

briar-android/build.gradle

@@ -104,6 +104,7 @@ dependencies {
 	}
 	implementation "com.android.support:cardview-v7:$supportVersion"
 	implementation "com.android.support:support-annotations:$supportVersion"
+	implementation "com.android.support:exifinterface:$supportVersion"
 	implementation 'com.android.support.constraint:constraint-layout:1.1.3'
 	implementation "android.arch.lifecycle:extensions:1.1.1"
 
@@ -117,8 +118,15 @@ dependencies {
 	implementation 'com.google.zxing:core:3.3.3'
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:2.12.4'
 	implementation 'com.vanniktech:emoji-google:0.5.1'
+	def glideVersion = '4.8.0'
+	implementation("com.github.bumptech.glide:glide:$glideVersion") {
+		exclude group: 'com.android.support'
+		exclude module: 'disklrucache' // when there's no disk cache, we can't accidentally use it
+	}
+	implementation 'com.github.chrisbanes:PhotoView:2.1.4' // later versions already use androidx
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
+	annotationProcessor "com.github.bumptech.glide:compiler:$glideVersion"
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 

briar-android/proguard-rules.txt

@@ -30,3 +30,6 @@
 
 # Emoji
 -keep class com.vanniktech.emoji.**
+
+# Glide
+-dontwarn com.bumptech.glide.load.engine.cache.DiskLruCacheWrapper

briar-android/src/main/AndroidManifest.xml

@@ -113,6 +113,15 @@
 				/>
 		</activity>
 
+		<activity
+			android:name=".android.conversation.ImageActivity"
+			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity"
+			android:theme="@style/BriarTheme.Transparent.NoActionBar">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.conversation.ConversationActivity"/>
+		</activity>
+
 		<activity
 			android:name="org.briarproject.briar.android.privategroup.creation.CreateGroupActivity"
 			android:label="@string/groups_create_group_title"

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

@@ -29,6 +29,7 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.plugin.tor.CircumventionProvider;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreModule;
+import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.reporting.BriarReportSender;
 import org.briarproject.briar.android.view.TextInputView;
@@ -170,6 +171,8 @@ public interface AndroidComponent
 
 	void inject(TextInputView textInputView);
 
+	void inject(BriarModelLoader briarModelLoader);
+
 	// Eager singleton load
 	void inject(AppModule.EagerSingletons init);
 }

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

@@ -15,10 +15,11 @@ import org.briarproject.briar.android.blog.ReblogFragment;
 import org.briarproject.briar.android.blog.RssFeedImportActivity;
 import org.briarproject.briar.android.blog.RssFeedManageActivity;
 import org.briarproject.briar.android.blog.WriteBlogPostActivity;
-import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.contact.ContactListFragment;
 import org.briarproject.briar.android.contact.ContactModule;
+import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
+import org.briarproject.briar.android.conversation.ImageActivity;
 import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
@@ -110,6 +111,8 @@ public interface ActivityComponent {
 
 	void inject(ConversationActivity activity);
 
+	void inject(ImageActivity activity);
+
 	void inject(ForumInvitationActivity activity);
 
 	void inject(BlogInvitationActivity activity);

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

@@ -2,12 +2,11 @@ package org.briarproject.briar.android.activity;
 
 import android.annotation.SuppressLint;
 import android.content.Intent;
+import android.support.annotation.RequiresApi;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.Toolbar;
-import android.transition.Slide;
 import android.transition.Transition;
-import android.view.Gravity;
 import android.view.Window;
 import android.widget.CheckBox;
 
@@ -33,6 +32,7 @@ import static android.os.Build.VERSION.SDK_INT;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_UNLOCK;
+import static org.briarproject.briar.android.util.UiUtils.excludeSystemUi;
 import static org.briarproject.briar.android.util.UiUtils.getDozeWhitelistingIntent;
 import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
@@ -111,21 +111,28 @@ public abstract class BriarActivity extends BaseActivity {
 		lockManager.onActivityStop();
 	}
 
-	public void setSceneTransitionAnimation() {
-		if (SDK_INT < 21) return;
+	/**
+	 * Sets the transition animations.
+	 * @param enterTransition used to move views into initial positions
+	 * @param exitTransition used to move views out when starting a <b>new</b> activity.
+	 * @param returnTransition used when window is closing, because the activity is finishing.
+	 */
+	@RequiresApi(api = 21)
+	public void setSceneTransitionAnimation(
+			@Nullable Transition enterTransition,
+			@Nullable Transition exitTransition,
+			@Nullable Transition returnTransition) {
 		// workaround for #1007
 		if (isSamsung7()) {
 			return;
 		}
-		Transition slide = new Slide(Gravity.RIGHT);
-		slide.excludeTarget(android.R.id.statusBarBackground, true);
-		slide.excludeTarget(android.R.id.navigationBarBackground, true);
+		if (enterTransition != null) excludeSystemUi(enterTransition);
+		if (exitTransition != null) excludeSystemUi(exitTransition);
+		if (returnTransition != null) excludeSystemUi(returnTransition);
 		Window window = getWindow();
-		window.requestFeature(Window.FEATURE_CONTENT_TRANSITIONS);
-		window.setExitTransition(slide);
-		window.setEnterTransition(slide);
-		window.setTransitionBackgroundFadeDuration(getResources()
-				.getInteger(android.R.integer.config_longAnimTime));
+		window.setEnterTransition(enterTransition);
+		window.setExitTransition(exitTransition);
+		window.setReturnTransition(returnTransition);
 	}
 
 	/**

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

@@ -18,7 +18,6 @@ public class ReblogActivity extends BriarActivity implements
 
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
-		setSceneTransitionAnimation();
 		super.onCreate(savedInstanceState);
 
 		Intent intent = getIntent();

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

@@ -0,0 +1,209 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.res.Resources;
+import android.graphics.BitmapFactory;
+import android.support.annotation.Nullable;
+import android.support.media.ExifInterface;
+
+import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Logger;
+
+import static android.support.media.ExifInterface.ORIENTATION_ROTATE_270;
+import static android.support.media.ExifInterface.ORIENTATION_ROTATE_90;
+import static android.support.media.ExifInterface.ORIENTATION_TRANSPOSE;
+import static android.support.media.ExifInterface.ORIENTATION_TRANSVERSE;
+import static android.support.media.ExifInterface.TAG_IMAGE_LENGTH;
+import static android.support.media.ExifInterface.TAG_IMAGE_WIDTH;
+import static android.support.media.ExifInterface.TAG_ORIENTATION;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+
+@NotNullByDefault
+class AttachmentController {
+
+	private static final Logger LOG =
+			getLogger(AttachmentController.class.getName());
+
+	private final MessagingManager messagingManager;
+	private final int defaultSize;
+	private final int minWidth, maxWidth;
+	private final int minHeight, maxHeight;
+
+	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
+			new ConcurrentHashMap<>();
+
+	AttachmentController(MessagingManager messagingManager, Resources res) {
+		this.messagingManager = messagingManager;
+		defaultSize =
+				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
+		minWidth = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_min_width);
+		maxWidth = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_max_width);
+		minHeight = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_min_height);
+		maxHeight = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_max_height);
+	}
+
+	void put(MessageId messageId, List<AttachmentItem> attachments) {
+		attachmentCache.put(messageId, attachments);
+	}
+
+	@Nullable
+	List<AttachmentItem> get(MessageId messageId) {
+		return attachmentCache.get(messageId);
+	}
+
+	@DatabaseExecutor
+	List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
+			List<AttachmentHeader> headers) throws DbException {
+		long start = now();
+		List<Pair<AttachmentHeader, Attachment>> attachments =
+				new ArrayList<>(headers.size());
+		for (AttachmentHeader h : headers) {
+			Attachment a =
+					messagingManager.getAttachment(h.getMessageId());
+			attachments.add(new Pair<>(h, a));
+		}
+		logDuration(LOG, "Loading attachment", start);
+		return attachments;
+	}
+
+	List<AttachmentItem> getAttachmentItems(
+			List<Pair<AttachmentHeader, Attachment>> attachments) {
+		List<AttachmentItem> items = new ArrayList<>(attachments.size());
+		for (Pair<AttachmentHeader, Attachment> a : attachments) {
+			AttachmentItem item =
+					getAttachmentItem(a.getFirst(), a.getSecond());
+			items.add(item);
+		}
+		return items;
+	}
+
+	private AttachmentItem getAttachmentItem(AttachmentHeader h, Attachment a) {
+		MessageId messageId = h.getMessageId();
+		Size size = new Size();
+
+		InputStream is = a.getStream();
+		is.mark(Integer.MAX_VALUE);
+		try {
+			// use exif to get size
+			if (h.getContentType().equals("image/jpeg")) {
+				size = getSizeFromExif(is);
+			}
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+		try {
+			// use BitmapFactory to get size
+			if (size.error) {
+				is.reset();
+				size = getSizeFromBitmap(is);
+			}
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		} finally {
+			tryToClose(is, LOG, WARNING);
+		}
+
+		// calculate thumbnail size
+		Size thumbnailSize = new Size(defaultSize, defaultSize);
+		if (!size.error) {
+			thumbnailSize = getThumbnailSize(size.width, size.height);
+		}
+		return new AttachmentItem(messageId, size.width, size.height,
+				thumbnailSize.width, thumbnailSize.height, size.error);
+	}
+
+	/**
+	 * Gets the size of a JPEG {@link InputStream} if EXIF info is available.
+	 */
+	private static Size getSizeFromExif(InputStream is)
+			throws IOException {
+		ExifInterface exif = new ExifInterface(is);
+		// these can return 0 independent of default value
+		int width = exif.getAttributeInt(TAG_IMAGE_WIDTH, 0);
+		int height = exif.getAttributeInt(TAG_IMAGE_LENGTH, 0);
+		if (width == 0 || height == 0) return new Size();
+		int orientation = exif.getAttributeInt(TAG_ORIENTATION, 0);
+		if (orientation == ORIENTATION_ROTATE_90 ||
+				orientation == ORIENTATION_ROTATE_270 ||
+				orientation == ORIENTATION_TRANSVERSE ||
+				orientation == ORIENTATION_TRANSPOSE) {
+			//noinspection SuspiciousNameCombination
+			return new Size(height, width);
+		}
+		return new Size(width, height);
+	}
+
+	/**
+	 * Gets the size of any image {@link InputStream}.
+	 */
+	private static Size getSizeFromBitmap(InputStream is) {
+		BitmapFactory.Options options = new BitmapFactory.Options();
+		options.inJustDecodeBounds = true;
+		BitmapFactory.decodeStream(is, null, options);
+		if (options.outWidth < 1 || options.outHeight < 1)
+			return new Size();
+		return new Size(options.outWidth, options.outHeight);
+	}
+
+	private Size getThumbnailSize(int width, int height) {
+		float widthPercentage = maxWidth / (float) width;
+		float heightPercentage = maxHeight / (float) height;
+		float scaleFactor = Math.min(widthPercentage, heightPercentage);
+		if (scaleFactor > 1) scaleFactor = 1f;
+		int thumbnailWidth = (int) (width * scaleFactor);
+		int thumbnailHeight = (int) (height * scaleFactor);
+		if (thumbnailWidth < minWidth || thumbnailHeight < minHeight) {
+			widthPercentage = minWidth / (float) width;
+			heightPercentage = minHeight / (float) height;
+			scaleFactor = Math.max(widthPercentage, heightPercentage);
+			thumbnailWidth = (int) (width * scaleFactor);
+			thumbnailHeight = (int) (height * scaleFactor);
+			if (thumbnailWidth > maxWidth) thumbnailWidth = maxWidth;
+			if (thumbnailHeight > maxHeight) thumbnailHeight = maxHeight;
+		}
+		return new Size(thumbnailWidth, thumbnailHeight);
+	}
+
+	private static class Size {
+
+		private final int width;
+		private final int height;
+		private final boolean error;
+
+		private Size(int width, int height) {
+			this.width = width;
+			this.height = height;
+			this.error = false;
+		}
+
+		private Size() {
+			this.width = 0;
+			this.height = 0;
+			this.error = true;
+		}
+	}
+
+}

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

@@ -0,0 +1,98 @@
+package org.briarproject.briar.android.conversation;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentItem implements Parcelable {
+
+	private final MessageId messageId;
+	private final int width, height;
+	private final int thumbnailWidth, thumbnailHeight;
+	private final boolean hasError;
+
+	public static final Creator<AttachmentItem> CREATOR =
+			new Creator<AttachmentItem>() {
+				@Override
+				public AttachmentItem createFromParcel(Parcel in) {
+					return new AttachmentItem(in);
+				}
+
+				@Override
+				public AttachmentItem[] newArray(int size) {
+					return new AttachmentItem[size];
+				}
+			};
+
+	AttachmentItem(MessageId messageId, int width, int height,
+			int thumbnailWidth, int thumbnailHeight, boolean hasError) {
+		this.messageId = messageId;
+		this.width = width;
+		this.height = height;
+		this.thumbnailWidth = thumbnailWidth;
+		this.thumbnailHeight = thumbnailHeight;
+		this.hasError = hasError;
+	}
+
+	protected AttachmentItem(Parcel in) {
+		byte[] messageIdByte = new byte[MessageId.LENGTH];
+		in.readByteArray(messageIdByte);
+		messageId = new MessageId(messageIdByte);
+		width = in.readInt();
+		height = in.readInt();
+		thumbnailWidth = in.readInt();
+		thumbnailHeight = in.readInt();
+		hasError = in.readByte() != 0;
+	}
+
+	public MessageId getMessageId() {
+		return messageId;
+	}
+
+	int getWidth() {
+		return width;
+	}
+
+	int getHeight() {
+		return height;
+	}
+
+	int getThumbnailWidth() {
+		return thumbnailWidth;
+	}
+
+	int getThumbnailHeight() {
+		return thumbnailHeight;
+	}
+
+	boolean hasError() {
+		return hasError;
+	}
+
+	// TODO use counter instead, because in theory one attachment can appear in more than one messages
+	String getTransitionName() {
+		return String.valueOf(messageId.hashCode());
+	}
+
+	@Override
+	public int describeContents() {
+		return 0;
+	}
+
+	@Override
+	public void writeToParcel(Parcel dest, int flags) {
+		dest.writeByteArray(messageId.getBytes());
+		dest.writeInt(width);
+		dest.writeInt(height);
+		dest.writeInt(thumbnailWidth);
+		dest.writeInt(thumbnailHeight);
+		dest.writeByte((byte) (hasError ? 1 : 0));
+	}
+
+}

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

@@ -9,11 +9,15 @@ import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.support.design.widget.Snackbar;
+import android.support.v4.app.ActivityCompat;
+import android.support.v4.app.ActivityOptionsCompat;
 import android.support.v4.content.ContextCompat;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.ActionMenuView;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.Toolbar;
+import android.transition.Slide;
+import android.transition.Transition;
 import android.util.SparseArray;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -24,6 +28,7 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
@@ -51,6 +56,7 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.blog.BlogActivity;
+import org.briarproject.briar.android.conversation.ConversationVisitor.AttachmentCache;
 import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
@@ -69,6 +75,8 @@ import org.briarproject.briar.api.conversation.ConversationResponse;
 import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.introduction.IntroductionManager;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
@@ -92,8 +100,11 @@ import im.delight.android.identicons.IdenticonDrawable;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.PromptStateChangeListener;
 
+import static android.os.Build.VERSION.SDK_INT;
+import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static android.support.v4.view.ViewCompat.setTransitionName;
 import static android.support.v7.util.SortedList.INVALID_POSITION;
+import static android.view.Gravity.END;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.sort;
@@ -104,6 +115,9 @@ import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRODUCTION;
+import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT;
+import static org.briarproject.briar.android.conversation.ImageActivity.DATE;
+import static org.briarproject.briar.android.conversation.ImageActivity.NAME;
 import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 import static org.briarproject.briar.android.util.UiUtils.getAvatarTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
@@ -116,7 +130,7 @@ import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.S
 @ParametersNotNullByDefault
 public class ConversationActivity extends BriarActivity
 		implements EventListener, ConversationListener, TextInputListener,
-		TextCache {
+		TextCache, AttachmentCache {
 
 	public static final String CONTACT_ID = "briar.CONTACT_ID";
 
@@ -134,6 +148,7 @@ public class ConversationActivity extends BriarActivity
 	Executor cryptoExecutor;
 
 	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private AttachmentController attachmentController;
 
 	private ConversationViewModel viewModel;
 	private ConversationVisitor visitor;
@@ -143,6 +158,7 @@ public class ConversationActivity extends BriarActivity
 	private ImageView toolbarStatus;
 	private TextView toolbarTitle;
 	private BriarRecyclerView list;
+	private LinearLayoutManager layoutManager;
 	private TextInputView textInputView;
 
 	// Fields that are accessed from background threads must be volatile
@@ -180,7 +196,10 @@ public class ConversationActivity extends BriarActivity
 
 	@Override
 	public void onCreate(@Nullable Bundle state) {
-		setSceneTransitionAnimation();
+		if (SDK_INT >= 21) {
+			Transition slide = new Slide(END);
+			setSceneTransitionAnimation(slide, null, slide);
+		}
 		super.onCreate(state);
 
 		Intent i = getIntent();
@@ -191,6 +210,7 @@ public class ConversationActivity extends BriarActivity
 		viewModel = ViewModelProviders.of(this, viewModelFactory)
 				.get(ConversationViewModel.class);
 		viewModel.setContactId(contactId);
+		attachmentController = viewModel.getAttachmentController();
 
 		setContentView(R.layout.activity_conversation);
 
@@ -217,11 +237,12 @@ public class ConversationActivity extends BriarActivity
 		setTransitionName(toolbarAvatar, getAvatarTransitionName(contactId));
 		setTransitionName(toolbarStatus, getBulbTransitionName(contactId));
 
-		visitor = new ConversationVisitor(this, this,
+		visitor = new ConversationVisitor(this, this, this,
 				viewModel.getContactDisplayName());
 		adapter = new ConversationAdapter(this, this);
 		list = findViewById(R.id.conversationView);
-		list.setLayoutManager(new LinearLayoutManager(this));
+		layoutManager = new LinearLayoutManager(this);
+		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.setEmptyText(getString(R.string.no_private_messages));
 
@@ -340,14 +361,30 @@ public class ConversationActivity extends BriarActivity
 					// If the latest header is a private message, eagerly load
 					// its text so we can set the scroll position correctly
 					ConversationMessageHeader latest = sorted.get(0);
-					if (latest instanceof PrivateMessageHeader &&
-							((PrivateMessageHeader) latest).hasText()) {
+					if (latest instanceof PrivateMessageHeader) {
 						MessageId id = latest.getId();
-						String text = textCache.get(id);
-						if (text == null) {
-							LOG.info("Eagerly loading text of latest message");
-							text = messagingManager.getMessageText(id);
-							textCache.put(id, text);
+						PrivateMessageHeader h = (PrivateMessageHeader) latest;
+						if (h.hasText()) {
+							String text = textCache.get(id);
+							if (text == null) {
+								LOG.info(
+										"Eagerly loading text of latest message");
+								text = messagingManager.getMessageText(id);
+								textCache.put(id, text);
+							}
+						}
+						if (!h.getAttachmentHeaders().isEmpty()) {
+							List<AttachmentItem> items =
+									attachmentController.get(id);
+							if (items == null) {
+								LOG.info(
+										"Eagerly loading image size for latest message");
+								items = attachmentController.getAttachmentItems(
+										attachmentController
+												.getMessageAttachments(
+														h.getAttachmentHeaders()));
+								attachmentController.put(id, items);
+							}
 						}
 					}
 				}
@@ -408,16 +445,44 @@ public class ConversationActivity extends BriarActivity
 	private void displayMessageText(MessageId m, String text) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			textCache.put(m, text);
-			SparseArray<ConversationMessageItem> messages =
-					adapter.getMessageItems();
-			for (int i = 0; i < messages.size(); i++) {
-				ConversationItem item = messages.valueAt(i);
-				if (item.getId().equals(m)) {
-					item.setText(text);
-					adapter.notifyItemChanged(messages.keyAt(i));
-					list.scrollToPosition(adapter.getItemCount() - 1);
-					return;
-				}
+			Pair<Integer, ConversationMessageItem> pair =
+					adapter.getMessageItem(m);
+			if (pair != null) {
+				pair.getSecond().setText(text);
+				boolean bottom = adapter.isScrolledToBottom(layoutManager);
+				adapter.notifyItemChanged(pair.getFirst());
+				if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
+			}
+		});
+	}
+
+	private void loadMessageAttachments(MessageId messageId,
+			List<AttachmentHeader> headers) {
+		runOnDbThread(() -> {
+			try {
+				List<Pair<AttachmentHeader, Attachment>> attachments =
+						attachmentController.getMessageAttachments(headers);
+				// TODO move getting the items off to the IoExecutor
+				List<AttachmentItem> items =
+						attachmentController.getAttachmentItems(attachments);
+				displayMessageAttachments(messageId, items);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void displayMessageAttachments(MessageId m,
+			List<AttachmentItem> items) {
+		runOnUiThreadUnlessDestroyed(() -> {
+			attachmentController.put(m, items);
+			Pair<Integer, ConversationMessageItem> pair =
+					adapter.getMessageItem(m);
+			if (pair != null) {
+				pair.getSecond().setAttachments(items);
+				boolean bottom = adapter.isScrolledToBottom(layoutManager);
+				adapter.notifyItemChanged(pair.getFirst());
+				if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
 			}
 		});
 	}
@@ -466,10 +531,10 @@ public class ConversationActivity extends BriarActivity
 
 	private void addConversationItem(ConversationItem item) {
 		runOnUiThreadUnlessDestroyed(() -> {
+			boolean bottom = adapter.isScrolledToBottom(layoutManager);
 			adapter.incrementRevision();
 			adapter.add(item);
-			// Scroll to the bottom
-			list.scrollToPosition(adapter.getItemCount() - 1);
+			if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
 		});
 	}
 
@@ -750,6 +815,31 @@ public class ConversationActivity extends BriarActivity
 		startActivity(i);
 	}
 
+	@Override
+	public void onAttachmentClicked(View view,
+			ConversationMessageItem messageItem, AttachmentItem item) {
+		String name;
+		if (messageItem.isIncoming()) {
+			// must be available when items are being displayed
+			name = viewModel.getContactDisplayName().getValue();
+		} else {
+			name = getString(R.string.you);
+		}
+		Intent i = new Intent(this, ImageActivity.class);
+		i.putExtra(ATTACHMENT, item);
+		i.putExtra(NAME, name);
+		i.putExtra(DATE, messageItem.getTime());
+		if (SDK_INT >= 23) {
+			String transitionName = item.getTransitionName();
+			ActivityOptionsCompat options =
+					makeSceneTransitionAnimation(this, view, transitionName);
+			ActivityCompat.startActivity(this, i, options.toBundle());
+		} else {
+			// work-around for android bug #224270
+			startActivity(i);
+		}
+	}
+
 	@DatabaseExecutor
 	private void respondToIntroductionRequest(SessionId sessionId,
 			boolean accept, long time) throws DbException {
@@ -782,4 +872,16 @@ public class ConversationActivity extends BriarActivity
 		if (text == null) loadMessageText(m);
 		return text;
 	}
+
+	@Override
+	public List<AttachmentItem> getAttachmentItems(MessageId m,
+			List<AttachmentHeader> headers) {
+		List<AttachmentItem> attachments = attachmentController.get(m);
+		if (attachments == null) {
+			loadMessageAttachments(m, headers);
+			return emptyList();
+		}
+		return attachments;
+	}
+
 }

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

@@ -2,12 +2,15 @@ package org.briarproject.briar.android.conversation;
 
 import android.content.Context;
 import android.support.annotation.LayoutRes;
+import android.support.v7.widget.LinearLayoutManager;
 import android.util.SparseArray;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.BriarAdapter;
 
@@ -98,16 +101,20 @@ class ConversationAdapter
 		return messages;
 	}
 
-	SparseArray<ConversationMessageItem> getMessageItems() {
-		SparseArray<ConversationMessageItem> messages = new SparseArray<>();
-
+	@Nullable
+	Pair<Integer, ConversationMessageItem> getMessageItem(MessageId messageId) {
 		for (int i = 0; i < items.size(); i++) {
 			ConversationItem item = items.get(i);
-			if (item instanceof ConversationMessageItem) {
-				messages.put(i, (ConversationMessageItem) item);
+			if (item instanceof ConversationMessageItem &&
+					item.getId().equals(messageId)) {
+				return new Pair<>(i, (ConversationMessageItem) item);
 			}
 		}
-		return messages;
+		return null;
+	}
+
+	boolean isScrolledToBottom(LinearLayoutManager layoutManager) {
+		return layoutManager.findLastVisibleItemPosition() == items.size() - 1;
 	}
 
 }

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

@@ -3,9 +3,9 @@ package org.briarproject.briar.android.conversation;
 import android.support.annotation.CallSuper;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
+import android.support.constraint.ConstraintLayout;
 import android.support.v7.widget.RecyclerView.ViewHolder;
 import android.view.View;
-import android.view.ViewGroup;
 import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -18,11 +18,11 @@ import static org.briarproject.briar.android.util.UiUtils.formatDate;
 @NotNullByDefault
 abstract class ConversationItemViewHolder extends ViewHolder {
 
-	protected final ViewGroup layout;
+	protected final ConstraintLayout layout;
 	@Nullable
 	private final OutItemViewHolder outViewHolder;
 	private final TextView text;
-	private final TextView time;
+	protected final TextView time;
 
 	ConversationItemViewHolder(View v, boolean isIncoming) {
 		super(v);

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

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.conversation;
 
 import android.support.annotation.UiThread;
+import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
@@ -14,4 +15,7 @@ interface ConversationListener {
 
 	void openRequestedShareable(ConversationRequestItem item);
 
+	void onAttachmentClicked(View view, ConversationMessageItem messageItem,
+			AttachmentItem attachmentItem);
+
 }

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

@@ -3,7 +3,6 @@ package org.briarproject.briar.android.conversation;
 import android.support.annotation.LayoutRes;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
 import java.util.List;
@@ -14,15 +13,20 @@ import javax.annotation.concurrent.NotThreadSafe;
 @NotNullByDefault
 class ConversationMessageItem extends ConversationItem {
 
-	private final List<AttachmentHeader> attachments;
+	private List<AttachmentItem> attachments;
 
-	ConversationMessageItem(@LayoutRes int layoutRes, PrivateMessageHeader h) {
+	ConversationMessageItem(@LayoutRes int layoutRes, PrivateMessageHeader h,
+			List<AttachmentItem> attachments) {
 		super(layoutRes, h);
-		this.attachments = h.getAttachmentHeaders();
+		this.attachments = attachments;
 	}
 
-	List<AttachmentHeader> getAttachments() {
+	List<AttachmentItem> getAttachments() {
 		return attachments;
 	}
 
+	void setAttachments(List<AttachmentItem> attachments) {
+		this.attachments = attachments;
+	}
+
 }

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

@@ -1,18 +1,161 @@
 package org.briarproject.briar.android.conversation;
 
+import android.content.res.Configuration;
+import android.graphics.Bitmap;
+import android.support.annotation.DrawableRes;
 import android.support.annotation.UiThread;
+import android.support.constraint.ConstraintSet;
+import android.support.v4.content.ContextCompat;
 import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+
+import com.bumptech.glide.load.Transformation;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.conversation.glide.BriarImageTransformation;
+import org.briarproject.briar.android.conversation.glide.GlideApp;
+
+import static android.os.Build.VERSION.SDK_INT;
+import static android.support.v4.view.ViewCompat.LAYOUT_DIRECTION_RTL;
+import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
+import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
 
 @UiThread
 @NotNullByDefault
 class ConversationMessageViewHolder extends ConversationItemViewHolder {
 
-	// image support will be added here (#1242)
+	@DrawableRes
+	private static final int ERROR_RES = R.drawable.ic_image_broken;
+
+	private final ImageView imageView;
+	private final ViewGroup statusLayout;
+	private final int timeColor, timeColorBubble;
+	private final int radiusBig, radiusSmall;
+	private final boolean isRtl;
+	private final ConstraintSet textConstraints = new ConstraintSet();
+	private final ConstraintSet imageConstraints = new ConstraintSet();
+	private final ConstraintSet imageTextConstraints = new ConstraintSet();
 
 	ConversationMessageViewHolder(View v, boolean isIncoming) {
 		super(v, isIncoming);
+		imageView = v.findViewById(R.id.imageView);
+		statusLayout = v.findViewById(R.id.statusLayout);
+		radiusBig = v.getContext().getResources()
+				.getDimensionPixelSize(R.dimen.message_bubble_radius_big);
+		radiusSmall = v.getContext().getResources()
+				.getDimensionPixelSize(R.dimen.message_bubble_radius_small);
+
+		// remember original status text color
+		timeColor = time.getCurrentTextColor();
+		timeColorBubble =
+				ContextCompat.getColor(v.getContext(), R.color.briar_white);
+
+		// find out if we are showing a RTL language, Use the configuration,
+		// because getting the layout direction of views is not reliable
+		Configuration config =
+				imageView.getContext().getResources().getConfiguration();
+		isRtl = SDK_INT >= 17 &&
+				config.getLayoutDirection() == LAYOUT_DIRECTION_RTL;
+
+		// clone constraint sets from layout files
+		textConstraints
+				.clone(v.getContext(), R.layout.list_item_conversation_msg_in);
+		imageConstraints.clone(v.getContext(),
+				R.layout.list_item_conversation_msg_image);
+		imageTextConstraints.clone(v.getContext(),
+				R.layout.list_item_conversation_msg_image_text);
+
+		// in/out are different layouts, so we need to do this only once
+		textConstraints
+				.setHorizontalBias(R.id.statusLayout, isIncoming() ? 1 : 0);
+		imageConstraints
+				.setHorizontalBias(R.id.statusLayout, isIncoming() ? 1 : 0);
+		imageTextConstraints
+				.setHorizontalBias(R.id.statusLayout, isIncoming() ? 1 : 0);
+	}
+
+	@Override
+	void bind(ConversationItem conversationItem,
+			ConversationListener listener) {
+		super.bind(conversationItem, listener);
+		ConversationMessageItem item =
+				(ConversationMessageItem) conversationItem;
+		if (item.getAttachments().isEmpty()) {
+			bindTextItem();
+		} else {
+			bindImageItem(item, listener);
+		}
+	}
+
+	private void bindTextItem() {
+		clearImage();
+		statusLayout.setBackgroundResource(0);
+		// also reset padding (the background drawable defines some)
+		statusLayout.setPadding(0, 0, 0, 0);
+		time.setTextColor(timeColor);
+		textConstraints.applyTo(layout);
+	}
+
+	private void bindImageItem(ConversationMessageItem item,
+			ConversationListener listener) {
+		// TODO show more than just the first image
+		AttachmentItem attachment = item.getAttachments().get(0);
+
+		ConstraintSet constraintSet;
+		if (item.getText() == null) {
+			statusLayout
+					.setBackgroundResource(R.drawable.msg_status_bubble);
+			time.setTextColor(timeColorBubble);
+			constraintSet = imageConstraints;
+		} else {
+			statusLayout.setBackgroundResource(0);
+			// also reset padding (the background drawable defines some)
+			statusLayout.setPadding(0, 0, 0, 0);
+			time.setTextColor(timeColor);
+			constraintSet = imageTextConstraints;
+		}
+
+		// apply image size constraints, so glides picks them up for scaling
+		int width = attachment.getThumbnailWidth();
+		int height = attachment.getThumbnailHeight();
+		constraintSet.constrainWidth(R.id.imageView, width);
+		constraintSet.constrainHeight(R.id.imageView, height);
+		constraintSet.applyTo(layout);
+
+		if (attachment.hasError()) {
+			clearImage();
+			imageView.setImageResource(ERROR_RES);
+		} else {
+			loadImage(item, attachment, listener);
+		}
+	}
+
+	private void clearImage() {
+		GlideApp.with(imageView)
+				.clear(imageView);
+		imageView.setOnClickListener(null);
+	}
+
+	private void loadImage(ConversationMessageItem item,
+			AttachmentItem attachment, ConversationListener listener) {
+		boolean leftCornerSmall =
+				(isIncoming() && !isRtl) || (!isIncoming() && isRtl);
+		boolean bottomRound = item.getText() == null;
+		Transformation<Bitmap> transformation = new BriarImageTransformation(
+				radiusSmall, radiusBig, leftCornerSmall, bottomRound);
+
+		GlideApp.with(imageView)
+				.load(attachment)
+				.diskCacheStrategy(NONE)
+				.error(ERROR_RES)
+				.transform(transformation)
+				.transition(withCrossFade())
+				.into(imageView)
+				.waitForLayout();
+		imageView.setOnClickListener(
+				view -> listener.onAttachmentClicked(view, item, attachment));
 	}
 
 }

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

@@ -0,0 +1,19 @@
+package org.briarproject.briar.android.conversation;
+
+import org.briarproject.briar.android.activity.ActivityScope;
+import org.briarproject.briar.android.conversation.glide.BriarDataFetcherFactory;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class ConversationModule {
+
+	@ActivityScope
+	@Provides
+	BriarDataFetcherFactory provideBriarDataFetcherFactory(
+			BriarDataFetcherFactory dataFetcherFactory) {
+		return dataFetcherFactory;
+	}
+
+}

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

@@ -16,6 +16,7 @@ import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.util.UiUtils;
+import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -38,6 +39,7 @@ public class ConversationViewModel extends AndroidViewModel {
 	@DatabaseExecutor
 	private final Executor dbExecutor;
 	private final ContactManager contactManager;
+	private final AttachmentController attachmentController;
 
 	@Nullable
 	private ContactId contactId = null;
@@ -52,10 +54,12 @@ public class ConversationViewModel extends AndroidViewModel {
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
-			ContactManager contactManager) {
+			ContactManager contactManager, MessagingManager messagingManager) {
 		super(application);
 		this.dbExecutor = dbExecutor;
 		this.contactManager = contactManager;
+		this.attachmentController = new AttachmentController(messagingManager,
+				application.getResources());
 		contactDeleted.setValue(false);
 	}
 
@@ -96,6 +100,10 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
+	AttachmentController getAttachmentController() {
+		return attachmentController;
+	}
+
 	LiveData<Contact> getContact() {
 		return contact;
 	}

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

@@ -14,12 +14,16 @@ import org.briarproject.briar.api.forum.ForumInvitationRequest;
 import org.briarproject.briar.api.forum.ForumInvitationResponse;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
 
+import java.util.List;
+
 import javax.annotation.Nullable;
 
+import static java.util.Collections.emptyList;
 import static org.briarproject.briar.android.conversation.ConversationRequestItem.RequestType.BLOG;
 import static org.briarproject.briar.android.conversation.ConversationRequestItem.RequestType.FORUM;
 import static org.briarproject.briar.android.conversation.ConversationRequestItem.RequestType.GROUP;
@@ -33,24 +37,33 @@ class ConversationVisitor implements
 
 	private final Context ctx;
 	private final TextCache textCache;
+	private final AttachmentCache attachmentCache;
 	private final LiveData<String> contactName;
 
 	ConversationVisitor(Context ctx, TextCache textCache,
-			LiveData<String> contactName) {
+			AttachmentCache attachmentCache, LiveData<String> contactName) {
 		this.ctx = ctx;
 		this.textCache = textCache;
+		this.attachmentCache = attachmentCache;
 		this.contactName = contactName;
 	}
 
 	@Override
 	public ConversationItem visitPrivateMessageHeader(PrivateMessageHeader h) {
 		ConversationItem item;
+		List<AttachmentItem> attachments;
+		if (h.getAttachmentHeaders().isEmpty()) {
+			attachments = emptyList();
+		} else {
+			attachments = attachmentCache
+					.getAttachmentItems(h.getId(), h.getAttachmentHeaders());
+		}
 		if (h.isLocal()) {
 			item = new ConversationMessageItem(
-					R.layout.list_item_conversation_msg_out, h);
+					R.layout.list_item_conversation_msg_out, h, attachments);
 		} else {
 			item = new ConversationMessageItem(
-					R.layout.list_item_conversation_msg_in, h);
+					R.layout.list_item_conversation_msg_in, h, attachments);
 		}
 		if (h.hasText()) {
 			String text = textCache.getText(h.getId());
@@ -279,4 +292,9 @@ class ConversationVisitor implements
 		@Nullable
 		String getText(MessageId m);
 	}
+
+	interface AttachmentCache {
+		List<AttachmentItem> getAttachmentItems(MessageId m,
+				List<AttachmentHeader> headers);
+	}
 }

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

@@ -0,0 +1,233 @@
+package org.briarproject.briar.android.conversation;
+
+import android.graphics.drawable.Animatable;
+import android.graphics.drawable.Drawable;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.annotation.RequiresApi;
+import android.support.design.widget.AppBarLayout;
+import android.support.v7.widget.Toolbar;
+import android.transition.Fade;
+import android.transition.Transition;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.Window;
+import android.widget.TextView;
+
+import com.bumptech.glide.load.DataSource;
+import com.bumptech.glide.load.engine.GlideException;
+import com.bumptech.glide.request.RequestListener;
+import com.bumptech.glide.request.target.Target;
+import com.github.chrisbanes.photoview.PhotoView;
+
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.conversation.glide.GlideApp;
+import org.briarproject.briar.android.view.PullDownLayout;
+
+import static android.graphics.Color.TRANSPARENT;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.view.View.GONE;
+import static android.view.View.SYSTEM_UI_FLAG_FULLSCREEN;
+import static android.view.View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
+import static android.view.View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
+import static android.view.View.VISIBLE;
+import static android.view.WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
+import static android.widget.ImageView.ScaleType.FIT_START;
+import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
+import static java.util.Objects.requireNonNull;
+import static org.briarproject.briar.android.util.UiUtils.formatDateAbsolute;
+
+public class ImageActivity extends BriarActivity
+		implements PullDownLayout.Callback {
+
+	final static String ATTACHMENT = "attachment";
+	final static String NAME = "name";
+	final static String DATE = "date";
+
+	private PullDownLayout layout;
+	private AppBarLayout appBarLayout;
+	private PhotoView photoView;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+
+		// Transitions
+		supportPostponeEnterTransition();
+		Window window = getWindow();
+		if (SDK_INT >= 21) {
+			Transition transition = new Fade();
+			setSceneTransitionAnimation(transition, null, transition);
+		}
+
+		// inflate layout
+		setContentView(R.layout.activity_image);
+		layout = findViewById(R.id.layout);
+		layout.getBackground().setAlpha(255);
+		layout.setCallback(this);
+
+		// Status Bar
+		if (SDK_INT >= 21) {
+			window.setStatusBarColor(TRANSPARENT);
+		} else if (SDK_INT >= 19) {
+			// we can't make the status bar transparent, but translucent
+			window.addFlags(FLAG_TRANSLUCENT_STATUS);
+		}
+
+		// Toolbar
+		appBarLayout = findViewById(R.id.appBarLayout);
+		Toolbar toolbar = requireNonNull(setUpCustomToolbar(true));
+		TextView contactName = toolbar.findViewById(R.id.contactName);
+		TextView dateView = toolbar.findViewById(R.id.dateView);
+
+		// Intent Extras
+		AttachmentItem attachment = getIntent().getParcelableExtra(ATTACHMENT);
+		String name = getIntent().getStringExtra(NAME);
+		long time = getIntent().getLongExtra(DATE, 0);
+		String date = formatDateAbsolute(this, time);
+		contactName.setText(name);
+		dateView.setText(date);
+
+		// Image View
+		photoView = findViewById(R.id.photoView);
+		if (SDK_INT >= 16) {
+			photoView.setOnClickListener(view -> toggleSystemUi());
+			window.getDecorView().setSystemUiVisibility(
+					SYSTEM_UI_FLAG_LAYOUT_STABLE |
+							SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
+		}
+
+		// Request Listener
+		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
+			@Override
+			public boolean onLoadFailed(@Nullable GlideException e,
+					Object model, Target<Drawable> target,
+					boolean isFirstResource) {
+				supportStartPostponedEnterTransition();
+				return false;
+			}
+
+			@Override
+			public boolean onResourceReady(Drawable resource, Object model,
+					Target<Drawable> target, DataSource dataSource,
+					boolean isFirstResource) {
+				if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
+					// set transition name only when not animatable,
+					// because the animation won't start otherwise
+					photoView.setTransitionName(
+							attachment.getTransitionName());
+				}
+				// Move image to the top if overlapping toolbar
+				if (isOverlappingToolbar(resource)) {
+					photoView.setScaleType(FIT_START);
+				}
+				supportStartPostponedEnterTransition();
+				return false;
+			}
+		};
+
+		// Load Image
+		GlideApp.with(this)
+				.load(attachment)
+				.diskCacheStrategy(NONE)
+				.error(R.drawable.ic_image_broken)
+				.dontTransform()
+				.addListener(listener)
+				.into(photoView);
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		switch (item.getItemId()) {
+			case android.R.id.home:
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
+		}
+	}
+
+	@Override
+	public void onPullStart() {
+		appBarLayout.animate()
+				.alpha(0f)
+				.start();
+	}
+
+	@Override
+	public void onPull(float progress) {
+		layout.getBackground().setAlpha(Math.round((1 - progress) * 255));
+	}
+
+	@Override
+	public void onPullCancel() {
+		appBarLayout.animate()
+				.alpha(1f)
+				.start();
+	}
+
+	@Override
+	public void onPullComplete() {
+		supportFinishAfterTransition();
+	}
+
+	@RequiresApi(api = 16)
+	private void toggleSystemUi() {
+		View decorView = getWindow().getDecorView();
+		if (appBarLayout.getVisibility() == VISIBLE) {
+			hideSystemUi(decorView);
+		} else {
+			showSystemUi(decorView);
+		}
+	}
+
+	@RequiresApi(api = 16)
+	private void hideSystemUi(View decorView) {
+		decorView.setSystemUiVisibility(SYSTEM_UI_FLAG_LAYOUT_STABLE
+				| SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+				| SYSTEM_UI_FLAG_FULLSCREEN
+		);
+		appBarLayout.animate()
+				.translationYBy(-1 * appBarLayout.getHeight())
+				.alpha(0f)
+				.withEndAction(() -> appBarLayout.setVisibility(GONE))
+				.start();
+	}
+
+	@RequiresApi(api = 16)
+	private void showSystemUi(View decorView) {
+		decorView.setSystemUiVisibility(
+				SYSTEM_UI_FLAG_LAYOUT_STABLE
+						| SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+		);
+		appBarLayout.animate()
+				.translationYBy(appBarLayout.getHeight())
+				.alpha(1f)
+				.withStartAction(() -> appBarLayout.setVisibility(VISIBLE))
+				.start();
+	}
+
+	private boolean isOverlappingToolbar(Drawable drawable) {
+		int width = drawable.getIntrinsicWidth();
+		int height = drawable.getIntrinsicHeight();
+		float widthPercentage = photoView.getWidth() / (float) width;
+		float heightPercentage = photoView.getHeight() / (float) height;
+		float scaleFactor = Math.min(widthPercentage, heightPercentage);
+		int realWidth = (int) (width * scaleFactor);
+		int realHeight = (int) (height * scaleFactor);
+		// return if photo doesn't use the full width,
+		// because it will be moved to the right otherwise
+		if (realWidth < photoView.getWidth()) return false;
+		int drawableTop = (photoView.getHeight() - realHeight) / 2;
+		return drawableTop < appBarLayout.getBottom() &&
+				drawableTop != appBarLayout.getTop();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarDataFetcher.java

@@ -0,0 +1,85 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import android.support.annotation.Nullable;
+
+import com.bumptech.glide.Priority;
+import com.bumptech.glide.load.DataSource;
+import com.bumptech.glide.load.data.DataFetcher;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.io.InputStream;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static com.bumptech.glide.load.DataSource.LOCAL;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
+
+@NotNullByDefault
+class BriarDataFetcher implements DataFetcher<InputStream> {
+
+	private final static Logger LOG =
+			getLogger(BriarDataFetcher.class.getName());
+
+	private final MessagingManager messagingManager;
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+	private final AttachmentItem attachment;
+
+	@Nullable
+	private volatile InputStream inputStream;
+	private volatile boolean cancel = false;
+
+	@Inject
+	public BriarDataFetcher(MessagingManager messagingManager,
+			@DatabaseExecutor Executor dbExecutor, AttachmentItem attachment) {
+		this.messagingManager = messagingManager;
+		this.dbExecutor = dbExecutor;
+		this.attachment = attachment;
+	}
+
+	@Override
+	public void loadData(Priority priority,
+			DataCallback<? super InputStream> callback) {
+		MessageId id = attachment.getMessageId();
+		dbExecutor.execute(() -> {
+			if (cancel) return;
+			try {
+				inputStream = messagingManager.getAttachment(id).getStream();
+				callback.onDataReady(inputStream);
+			} catch (DbException e) {
+				callback.onLoadFailed(e);
+			}
+		});
+	}
+
+	@Override
+	public void cleanup() {
+		tryToClose(inputStream, LOG, WARNING);
+	}
+
+	@Override
+	public void cancel() {
+		cancel = true;
+	}
+
+	@Override
+	public Class<InputStream> getDataClass() {
+		return InputStream.class;
+	}
+
+	@Override
+	public DataSource getDataSource() {
+		return LOCAL;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarDataFetcherFactory.java

@@ -0,0 +1,30 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+@NotNullByDefault
+public class BriarDataFetcherFactory {
+
+	private final MessagingManager messagingManager;
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+
+	@Inject
+	public BriarDataFetcherFactory(MessagingManager messagingManager,
+			@DatabaseExecutor Executor dbExecutor) {
+		this.messagingManager = messagingManager;
+		this.dbExecutor = dbExecutor;
+	}
+
+	BriarDataFetcher createBriarDataFetcher(AttachmentItem model) {
+		return new BriarDataFetcher(messagingManager, dbExecutor, model);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarGlideModule.java

@@ -0,0 +1,44 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.GlideBuilder;
+import com.bumptech.glide.Registry;
+import com.bumptech.glide.annotation.GlideModule;
+import com.bumptech.glide.module.AppGlideModule;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.BriarApplication;
+import org.briarproject.briar.android.conversation.AttachmentItem;
+
+import java.io.InputStream;
+
+import static android.util.Log.DEBUG;
+import static android.util.Log.WARN;
+import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
+
+@GlideModule
+@NotNullByDefault
+public final class BriarGlideModule extends AppGlideModule {
+
+	@Override
+	public void registerComponents(Context context, Glide glide,
+			Registry registry) {
+		BriarApplication app =
+				(BriarApplication) context.getApplicationContext();
+		BriarModelLoaderFactory factory = new BriarModelLoaderFactory(app);
+		registry.prepend(AttachmentItem.class, InputStream.class, factory);
+	}
+
+	@Override
+	public void applyOptions(Context context, GlideBuilder builder) {
+		builder.setLogLevel(IS_DEBUG_BUILD ? DEBUG : WARN);
+	}
+
+	@Override
+	public boolean isManifestParsingEnabled() {
+		return false;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarImageTransformation.java

@@ -0,0 +1,16 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import android.graphics.Bitmap;
+
+import com.bumptech.glide.load.MultiTransformation;
+import com.bumptech.glide.load.resource.bitmap.CenterCrop;
+
+public class BriarImageTransformation extends MultiTransformation<Bitmap> {
+
+	public BriarImageTransformation(int smallRadius, int radius,
+			boolean leftCornerSmall, boolean bottomRound) {
+		super(new CenterCrop(), new ImageCornerTransformation(
+				smallRadius, radius, leftCornerSmall, bottomRound));
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoader.java

@@ -0,0 +1,42 @@
+package org.briarproject.briar.android.conversation.glide;
+
+
+import com.bumptech.glide.load.Options;
+import com.bumptech.glide.load.model.ModelLoader;
+import com.bumptech.glide.signature.ObjectKey;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.android.BriarApplication;
+import org.briarproject.briar.android.conversation.AttachmentItem;
+
+import java.io.InputStream;
+
+import javax.inject.Inject;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public final class BriarModelLoader
+		implements ModelLoader<AttachmentItem, InputStream> {
+
+	@Inject
+	BriarDataFetcherFactory dataFetcherFactory;
+
+	public BriarModelLoader(BriarApplication app) {
+		app.getApplicationComponent().inject(this);
+	}
+
+	@Override
+	public LoadData<InputStream> buildLoadData(AttachmentItem model, int width,
+			int height, Options options) {
+		ObjectKey key = new ObjectKey(model.getMessageId());
+		BriarDataFetcher dataFetcher =
+				dataFetcherFactory.createBriarDataFetcher(model);
+		return new LoadData<>(key, dataFetcher);
+	}
+
+	@Override
+	public boolean handles(AttachmentItem model) {
+		return true;
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoaderFactory.java

@@ -0,0 +1,34 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import com.bumptech.glide.load.model.ModelLoader;
+import com.bumptech.glide.load.model.ModelLoaderFactory;
+import com.bumptech.glide.load.model.MultiModelLoaderFactory;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.BriarApplication;
+import org.briarproject.briar.android.conversation.AttachmentItem;
+
+import java.io.InputStream;
+
+@NotNullByDefault
+class BriarModelLoaderFactory
+		implements ModelLoaderFactory<AttachmentItem, InputStream> {
+
+	private final BriarApplication app;
+
+	public BriarModelLoaderFactory(BriarApplication app) {
+		this.app = app;
+	}
+
+	@Override
+	public ModelLoader<AttachmentItem, InputStream> build(
+			MultiModelLoaderFactory multiFactory) {
+		return new BriarModelLoader(app);
+	}
+
+	@Override
+	public void teardown() {
+		// noop
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/ImageCornerTransformation.java

@@ -0,0 +1,111 @@
+package org.briarproject.briar.android.conversation.glide;
+
+import android.graphics.Bitmap;
+import android.graphics.BitmapShader;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.RectF;
+import android.support.annotation.NonNull;
+
+import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
+import com.bumptech.glide.load.resource.bitmap.BitmapTransformation;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.security.MessageDigest;
+
+import javax.annotation.concurrent.Immutable;
+
+import static android.graphics.Bitmap.Config.ARGB_8888;
+import static android.graphics.Shader.TileMode.CLAMP;
+
+@Immutable
+@NotNullByDefault
+class ImageCornerTransformation extends BitmapTransformation {
+
+	private static final String ID = ImageCornerTransformation.class.getName();
+
+	private final int smallRadius, radius;
+	private final boolean leftCornerSmall, bottomRound;
+
+	ImageCornerTransformation(int smallRadius, int radius,
+			boolean leftCornerSmall, boolean bottomRound) {
+		this.smallRadius = smallRadius;
+		this.radius = radius;
+		this.leftCornerSmall = leftCornerSmall;
+		this.bottomRound = bottomRound;
+	}
+
+	@Override
+	protected Bitmap transform(BitmapPool pool, Bitmap toTransform,
+			int outWidth, int outHeight) {
+		int width = toTransform.getWidth();
+		int height = toTransform.getHeight();
+
+		Bitmap bitmap = pool.get(width, height, ARGB_8888);
+		bitmap.setHasAlpha(true);
+
+		Canvas canvas = new Canvas(bitmap);
+		Paint paint = new Paint();
+		paint.setAntiAlias(true);
+		paint.setShader(new BitmapShader(toTransform, CLAMP, CLAMP));
+		drawRect(canvas, paint, width, height);
+		return bitmap;
+	}
+
+	private void drawRect(Canvas canvas, Paint paint, float width,
+			float height) {
+		drawSmallCorner(canvas, paint, width);
+		drawBigCorners(canvas, paint, width, height);
+	}
+
+	private void drawSmallCorner(Canvas canvas, Paint paint, float width) {
+		float left = leftCornerSmall ? 0 : width - radius;
+		float right = leftCornerSmall ? radius : width;
+		canvas.drawRoundRect(new RectF(left, 0, right, radius),
+				smallRadius, smallRadius, paint);
+	}
+
+	private void drawBigCorners(Canvas canvas, Paint paint, float width,
+			float height) {
+		float top = bottomRound ? 0 : radius;
+		RectF rect = new RectF(0, top, width, height);
+		if (bottomRound) {
+			canvas.drawRoundRect(rect, radius, radius, paint);
+		} else {
+			canvas.drawRect(rect, paint);
+			canvas.drawRoundRect(new RectF(0, 0, width, radius * 2),
+					radius, radius, paint);
+		}
+	}
+
+	@Override
+	public String toString() {
+		return "ImageCornerTransformation(smallRadius=" + smallRadius +
+				", radius=" + radius + ", leftCornerSmall=" + leftCornerSmall +
+				", bottomRound=" + bottomRound + ")";
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof ImageCornerTransformation &&
+				((ImageCornerTransformation) o).smallRadius == smallRadius &&
+				((ImageCornerTransformation) o).radius == radius &&
+				((ImageCornerTransformation) o).leftCornerSmall ==
+						leftCornerSmall &&
+				((ImageCornerTransformation) o).bottomRound == bottomRound;
+	}
+
+	@Override
+	public int hashCode() {
+		return ID.hashCode() + (smallRadius << 16) ^ (radius << 2) ^
+				(leftCornerSmall ? 2 : 0) ^ (bottomRound ? 1 : 0);
+	}
+
+	@Override
+	public void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {
+		messageDigest.update((ID + '|' + smallRadius + '|' + radius + '|' +
+				leftCornerSmall + '|' + bottomRound).getBytes(CHARSET));
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -16,6 +16,7 @@ import android.support.annotation.ColorInt;
 import android.support.annotation.ColorRes;
 import android.support.annotation.MainThread;
 import android.support.annotation.Nullable;
+import android.support.annotation.RequiresApi;
 import android.support.design.widget.TextInputLayout;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.content.ContextCompat;
@@ -31,6 +32,7 @@ import android.text.method.LinkMovementMethod;
 import android.text.style.ClickableSpan;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.URLSpan;
+import android.transition.Transition;
 import android.util.TypedValue;
 import android.view.KeyEvent;
 import android.view.View;
@@ -60,12 +62,16 @@ import static android.support.v7.app.AppCompatDelegate.MODE_NIGHT_NO;
 import static android.support.v7.app.AppCompatDelegate.MODE_NIGHT_YES;
 import static android.support.v7.app.AppCompatDelegate.setDefaultNightMode;
 import static android.text.format.DateUtils.DAY_IN_MILLIS;
+import static android.text.format.DateUtils.FORMAT_ABBREV_ALL;
 import static android.text.format.DateUtils.FORMAT_ABBREV_MONTH;
 import static android.text.format.DateUtils.FORMAT_ABBREV_RELATIVE;
 import static android.text.format.DateUtils.FORMAT_ABBREV_TIME;
 import static android.text.format.DateUtils.FORMAT_SHOW_DATE;
+import static android.text.format.DateUtils.FORMAT_SHOW_TIME;
+import static android.text.format.DateUtils.FORMAT_SHOW_YEAR;
 import static android.text.format.DateUtils.MINUTE_IN_MILLIS;
 import static android.text.format.DateUtils.WEEK_IN_MILLIS;
+import static android.text.format.DateUtils.YEAR_IN_MILLIS;
 import static android.view.KeyEvent.ACTION_DOWN;
 import static android.view.KeyEvent.KEYCODE_ENTER;
 import static android.view.inputmethod.EditorInfo.IME_NULL;
@@ -117,6 +123,13 @@ public class UiUtils {
 				MIN_DATE_RESOLUTION, flags).toString();
 	}
 
+	public static String formatDateAbsolute(Context ctx, long time) {
+		int flags = FORMAT_SHOW_TIME | FORMAT_SHOW_DATE | FORMAT_ABBREV_ALL;
+		long diff = System.currentTimeMillis() - time;
+		if (diff >= YEAR_IN_MILLIS) flags |= FORMAT_SHOW_YEAR;
+		return DateUtils.formatDateTime(ctx, time, flags);
+	}
+
 	public static int getDaysUntilExpiry() {
 		long now = System.currentTimeMillis();
 		long daysBeforeExpiry = (EXPIRY_DATE - now) / 1000 / 60 / 60 / 24;
@@ -318,6 +331,12 @@ public class UiUtils {
 				keyEvent.getKeyCode() == KEYCODE_ENTER;
 	}
 
+	@RequiresApi(api = 21)
+	public static void excludeSystemUi(Transition transition) {
+		transition.excludeTarget(android.R.id.statusBarBackground, true);
+		transition.excludeTarget(android.R.id.navigationBarBackground, true);
+	}
+
 	/**
 	 * Observes the given {@link LiveData} until the first change.
 	 * If the LiveData's value is available, the {@link Observer} will be

briar-android/src/main/java/org/briarproject/briar/android/view/PullDownLayout.java

@@ -0,0 +1,161 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 XiNGRZ <xxx@oxo.ooo>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.briarproject.briar.android.view;
+
+import android.content.Context;
+import android.support.annotation.Nullable;
+import android.support.v4.view.ViewCompat;
+import android.support.v4.widget.ViewDragHelper;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewConfiguration;
+import android.widget.FrameLayout;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class PullDownLayout extends FrameLayout {
+
+	private final ViewDragHelper dragger;
+
+	private final int minimumFlingVelocity;
+
+	@Nullable
+	private Callback callback;
+
+	public PullDownLayout(Context context) {
+		this(context, null);
+	}
+
+	public PullDownLayout(Context context, @Nullable AttributeSet attrs) {
+		this(context, attrs, 0);
+	}
+
+	public PullDownLayout(Context context, @Nullable AttributeSet attrs,
+			int defStyleAttr) {
+		super(context, attrs, defStyleAttr);
+		dragger = ViewDragHelper.create(this, 1f / 8f, new ViewDragCallback());
+		minimumFlingVelocity =
+				ViewConfiguration.get(context).getScaledMinimumFlingVelocity();
+	}
+
+	public void setCallback(@Nullable Callback callback) {
+		this.callback = callback;
+	}
+
+	@Override
+	public boolean onInterceptTouchEvent(MotionEvent ev) {
+		return dragger.shouldInterceptTouchEvent(ev);
+	}
+
+	@Override
+	public boolean onTouchEvent(MotionEvent event) {
+		dragger.processTouchEvent(event);
+		return true;
+	}
+
+	@Override
+	public void computeScroll() {
+		if (dragger.continueSettling(true)) {
+			ViewCompat.postInvalidateOnAnimation(this);
+		}
+	}
+
+	public interface Callback {
+
+		void onPullStart();
+
+		void onPull(float progress);
+
+		void onPullCancel();
+
+		void onPullComplete();
+
+	}
+
+	private class ViewDragCallback extends ViewDragHelper.Callback {
+
+		@Override
+		public boolean tryCaptureView(View child, int pointerId) {
+			return true;
+		}
+
+		@Override
+		public int clampViewPositionHorizontal(View child, int left, int dx) {
+			return 0;
+		}
+
+		@Override
+		public int clampViewPositionVertical(View child, int top, int dy) {
+			return Math.max(0, top);
+		}
+
+		@Override
+		public int getViewHorizontalDragRange(View child) {
+			return 0;
+		}
+
+		@Override
+		public int getViewVerticalDragRange(View child) {
+			return getHeight();
+		}
+
+		@Override
+		public void onViewCaptured(View capturedChild, int activePointerId) {
+			if (callback != null) {
+				callback.onPullStart();
+			}
+		}
+
+		@Override
+		public void onViewPositionChanged(View changedView, int left, int top,
+				int dx, int dy) {
+			if (callback != null) {
+				callback.onPull((float) top / (float) getHeight());
+			}
+		}
+
+		@Override
+		public void onViewReleased(View releasedChild, float xvel, float yvel) {
+			int slop = yvel > minimumFlingVelocity ? getHeight() / 6 :
+					getHeight() / 3;
+			if (releasedChild.getTop() > slop) {
+				if (callback != null) {
+					callback.onPullComplete();
+				}
+			} else {
+				if (callback != null) {
+					callback.onPullCancel();
+				}
+
+				dragger.settleCapturedViewAt(0, 0);
+				invalidate();
+			}
+		}
+
+	}
+
+}

briar-android/src/main/res/drawable/ic_image_broken.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="200dp"
+        android:height="200dp"
+        android:viewportHeight="24.0"
+        android:viewportWidth="24.0">
+	<path
+		android:fillColor="#808080"
+		android:pathData="M21,5v6.59l-3,-3.01 -4,4.01 -4,-4 -4,4 -3,-3.01L3,5c0,-1.1 0.9,-2 2,-2h14c1.1,0 2,0.9 2,2zM18,11.42l3,3.01L21,19c0,1.1 -0.9,2 -2,2L5,21c-1.1,0 -2,-0.9 -2,-2v-6.58l3,2.99 4,-4 4,4 4,-3.99z"/>
+</vector>

briar-android/src/main/res/drawable/msg_in.xml

@@ -8,10 +8,10 @@
 		android:topLeftRadius="@dimen/message_bubble_radius_top_inner"
 		android:topRightRadius="@dimen/message_bubble_radius_top_outer"/>
 	<padding
-		android:bottom="@dimen/message_bubble_padding_bottom"
-		android:left="@dimen/message_bubble_padding_sides"
-		android:right="@dimen/message_bubble_padding_sides"
-		android:top="@dimen/message_bubble_padding_top"/>
+		android:bottom="@dimen/message_bubble_border"
+		android:left="@dimen/message_bubble_border"
+		android:right="@dimen/message_bubble_border"
+		android:top="@dimen/message_bubble_border"/>
 	<solid
 		android:color="@color/msg_in"/>
 	<stroke

briar-android/src/main/res/drawable/msg_out.xml

@@ -8,10 +8,10 @@
 		android:topLeftRadius="@dimen/message_bubble_radius_top_outer"
 		android:topRightRadius="@dimen/message_bubble_radius_top_inner"/>
 	<padding
-		android:bottom="@dimen/message_bubble_padding_bottom"
-		android:left="@dimen/message_bubble_padding_sides"
-		android:right="@dimen/message_bubble_padding_sides"
-		android:top="@dimen/message_bubble_padding_top"/>
+		android:bottom="@dimen/message_bubble_border"
+		android:left="@dimen/message_bubble_border"
+		android:right="@dimen/message_bubble_border"
+		android:top="@dimen/message_bubble_border"/>
 	<solid
 		android:color="@color/msg_out"/>
 	<stroke

briar-android/src/main/res/drawable/msg_status_bubble.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:shape="rectangle">
+	<corners
+		android:radius="@dimen/message_bubble_radius_big"/>
+	<padding
+		android:bottom="3dp"
+		android:left="7dp"
+		android:right="7dp"
+		android:top="2dp"/>
+	<solid
+		android:color="@color/msg_status_bubble_background"/>
+</shape>

briar-android/src/main/res/layout/activity_image.xml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="utf-8"?>
+<org.briarproject.briar.android.view.PullDownLayout
+	android:id="@+id/layout"
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	android:background="@color/briar_black"
+	tools:context=".android.conversation.ImageActivity">
+
+	<com.github.chrisbanes.photoview.PhotoView
+		android:id="@+id/photoView"
+		android:layout_width="match_parent"
+		android:layout_height="match_parent"
+		tools:ignore="ContentDescription"
+		tools:srcCompat="@tools:sample/backgrounds/scenic"/>
+
+	<android.support.design.widget.AppBarLayout
+		android:id="@+id/appBarLayout"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:background="@color/msg_status_bubble_background">
+
+		<android.support.v7.widget.Toolbar
+			android:id="@+id/toolbar"
+			style="@style/BriarToolbar"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:background="@color/msg_status_bubble_background"
+			android:fitsSystemWindows="true">
+
+			<LinearLayout
+				android:layout_width="wrap_content"
+				android:layout_height="match_parent"
+				android:orientation="vertical">
+
+				<com.vanniktech.emoji.EmojiTextView
+					android:id="@+id/contactName"
+					style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title.Inverse"
+					android:layout_width="wrap_content"
+					android:layout_height="match_parent"
+					android:ellipsize="end"
+					android:maxLines="1"
+					android:textColor="@color/action_bar_text"
+					tools:text="Contact Name of someone who chose a long name"/>
+
+				<TextView
+					android:id="@+id/dateView"
+					android:layout_width="wrap_content"
+					android:layout_height="wrap_content"
+					android:textColor="@color/action_bar_text"
+					tools:text="date"/>
+
+			</LinearLayout>
+
+		</android.support.v7.widget.Toolbar>
+
+	</android.support.design.widget.AppBarLayout>
+
+</org.briarproject.briar.android.view.PullDownLayout>

briar-android/src/main/res/layout/list_item_conversation_msg_image.xml

@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	android:id="@+id/layout"
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="wrap_content"
+	android:layout_height="wrap_content"
+	android:layout_marginBottom="@dimen/message_bubble_margin"
+	android:layout_marginEnd="@dimen/message_bubble_margin_non_tail"
+	android:layout_marginLeft="@dimen/message_bubble_margin_tail"
+	android:layout_marginRight="@dimen/message_bubble_margin_non_tail"
+	android:layout_marginStart="@dimen/message_bubble_margin_tail"
+	android:layout_marginTop="@dimen/message_bubble_margin"
+	android:background="@drawable/msg_in"
+	android:elevation="@dimen/message_bubble_elevation">
+
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="@dimen/message_bubble_image_default"
+		android:layout_height="@dimen/message_bubble_image_default"
+		app:layout_constraintBottom_toTopOf="@+id/text"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		tools:ignore="ContentDescription"
+		tools:src="@drawable/alerts_and_states_error"/>
+
+	<com.vanniktech.emoji.EmojiTextView
+		android:id="@+id/text"
+		style="@style/TextMessage"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginTop="@dimen/message_bubble_padding_top_inner"
+		android:textColor="?android:attr/textColorPrimary"
+		android:visibility="gone"
+		app:layout_constrainedWidth="true"
+		app:layout_constraintBottom_toTopOf="@+id/statusLayout"
+		app:layout_constraintEnd_toEndOf="@+id/imageView"
+		app:layout_constraintHorizontal_bias="0.0"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/imageView"
+		tools:text="The text of a message which can sometimes be a bit longer as well"/>
+
+	<LinearLayout
+		android:id="@+id/statusLayout"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_top"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:background="@drawable/msg_status_bubble"
+		android:orientation="horizontal"
+		app:layout_constraintBottom_toBottomOf="@+id/imageView"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_bias="1.0"
+		app:layout_constraintStart_toStartOf="parent">
+
+		<TextView
+			android:id="@+id/time"
+			style="@style/TextMessage.Timestamp"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			tools:text="Dec 24, 13:37"/>
+
+	</LinearLayout>
+
+</android.support.constraint.ConstraintLayout>

briar-android/src/main/res/layout/list_item_conversation_msg_image_text.xml

@@ -0,0 +1,69 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	android:id="@+id/layout"
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="wrap_content"
+	android:layout_height="wrap_content"
+	android:layout_marginBottom="@dimen/message_bubble_margin"
+	android:layout_marginEnd="@dimen/message_bubble_margin_non_tail"
+	android:layout_marginLeft="@dimen/message_bubble_margin_tail"
+	android:layout_marginRight="@dimen/message_bubble_margin_non_tail"
+	android:layout_marginStart="@dimen/message_bubble_margin_tail"
+	android:layout_marginTop="@dimen/message_bubble_margin"
+	android:background="@drawable/msg_in"
+	android:elevation="@dimen/message_bubble_elevation">
+
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="@dimen/message_bubble_image_default"
+		android:layout_height="@dimen/message_bubble_image_default"
+		app:layout_constraintBottom_toTopOf="@+id/text"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		tools:ignore="ContentDescription"
+		tools:src="@drawable/alerts_and_states_error"/>
+
+	<com.vanniktech.emoji.EmojiTextView
+		android:id="@+id/text"
+		style="@style/TextMessage"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginTop="@dimen/message_bubble_padding_top_inner"
+		android:textColor="?android:attr/textColorPrimary"
+		app:layout_constrainedWidth="true"
+		app:layout_constraintBottom_toTopOf="@+id/statusLayout"
+		app:layout_constraintEnd_toEndOf="@+id/imageView"
+		app:layout_constraintHorizontal_bias="0.0"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/imageView"
+		tools:text="The text of a message which can sometimes be a bit longer as well"/>
+
+	<LinearLayout
+		android:id="@+id/statusLayout"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:orientation="horizontal"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_bias="1.0"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/text">
+
+		<TextView
+			android:id="@+id/time"
+			style="@style/TextMessage.Timestamp"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			tools:text="Dec 24, 13:37"/>
+
+	</LinearLayout>
+
+</android.support.constraint.ConstraintLayout>

briar-android/src/main/res/layout/list_item_conversation_msg_in.xml

@@ -15,29 +15,55 @@
 	android:background="@drawable/msg_in"
 	android:elevation="@dimen/message_bubble_elevation">
 
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="@dimen/message_bubble_image_default"
+		android:layout_height="@dimen/message_bubble_image_default"
+		android:visibility="gone"
+		app:layout_constraintBottom_toTopOf="@+id/text"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		tools:ignore="ContentDescription"/>
+
 	<com.vanniktech.emoji.EmojiTextView
 		android:id="@+id/text"
 		style="@style/TextMessage"
 		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginTop="@dimen/message_bubble_padding_top_inner"
 		android:textColor="?android:attr/textColorPrimary"
-		app:layout_constraintBottom_toTopOf="@+id/time"
-		app:layout_constraintEnd_toEndOf="@+id/time"
+		app:layout_constrainedWidth="true"
+		app:layout_constraintBottom_toTopOf="@+id/statusLayout"
+		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintHorizontal_bias="0.0"
 		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toTopOf="parent"
-		tools:text="Short message"/>
+		app:layout_constraintTop_toBottomOf="@+id/imageView"
+		tools:text="The text of a message which can sometimes be a bit longer as well"/>
 
-	<TextView
-		android:id="@+id/time"
-		style="@style/TextMessage.Timestamp"
+	<LinearLayout
+		android:id="@+id/statusLayout"
 		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
+		android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+		android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+		android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+		android:orientation="horizontal"
 		app:layout_constraintBottom_toBottomOf="parent"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintHorizontal_bias="1.0"
 		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toBottomOf="@+id/text"
-		tools:text="Dec 24, 13:37"/>
+		app:layout_constraintTop_toBottomOf="@+id/text">
+
+		<TextView
+			android:id="@+id/time"
+			style="@style/TextMessage.Timestamp"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			tools:text="Dec 24, 13:37"/>
+
+	</LinearLayout>
 
 </android.support.constraint.ConstraintLayout>

briar-android/src/main/res/layout/list_item_conversation_msg_out.xml

@@ -21,39 +21,68 @@
 		android:background="@drawable/msg_out"
 		android:elevation="@dimen/message_bubble_elevation">
 
+		<ImageView
+			android:id="@+id/imageView"
+			android:layout_width="@dimen/message_bubble_image_default"
+			android:layout_height="@dimen/message_bubble_image_default"
+			android:visibility="gone"
+			app:layout_constraintBottom_toTopOf="@+id/text"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toTopOf="parent"
+			tools:ignore="ContentDescription"
+			tools:src="@drawable/alerts_and_states_error"/>
+
 		<com.vanniktech.emoji.EmojiTextView
 			android:id="@+id/text"
 			style="@style/TextMessage"
 			android:layout_width="wrap_content"
 			android:layout_height="wrap_content"
+			android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+			android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+			android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+			android:layout_marginTop="@dimen/message_bubble_padding_top_inner"
 			android:textColor="@color/briar_text_primary_inverse"
-			app:layout_constraintBottom_toTopOf="@+id/time"
+			app:layout_constrainedWidth="true"
+			app:layout_constraintBottom_toTopOf="@+id/statusLayout"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintHorizontal_bias="0.0"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/imageView"
 			tools:text="This is a long long long message that spans over several lines.\n\nIt ends here."/>
 
-		<TextView
-			android:id="@+id/time"
-			style="@style/TextMessage.Timestamp"
+		<LinearLayout
+			android:id="@+id/statusLayout"
 			android:layout_width="wrap_content"
 			android:layout_height="wrap_content"
-			android:layout_marginTop="@dimen/message_bubble_timestamp_margin"
-			android:textColor="@color/private_message_date_inverse"
+			android:layout_marginBottom="@dimen/message_bubble_padding_bottom_inner"
+			android:layout_marginLeft="@dimen/message_bubble_padding_sides_inner"
+			android:layout_marginRight="@dimen/message_bubble_padding_sides_inner"
+			android:orientation="horizontal"
+			app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintHorizontal_bias="0.0"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toBottomOf="@+id/text"
-			tools:text="Dec 24, 13:37"/>
+			tools:ignore="UseCompoundDrawables">
 
-		<ImageView
-			android:id="@+id/status"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:layout_marginLeft="@dimen/margin_medium"
-			android:layout_marginStart="@dimen/margin_medium"
-			app:layout_constraintBottom_toBottomOf="@+id/time"
-			app:layout_constraintStart_toEndOf="@+id/time"
-			app:layout_constraintTop_toTopOf="@+id/time"
-			tools:ignore="ContentDescription"
-			tools:src="@drawable/message_delivered"/>
+			<TextView
+				android:id="@+id/time"
+				style="@style/TextMessage.Timestamp"
+				android:layout_width="wrap_content"
+				android:layout_height="wrap_content"
+				android:layout_marginEnd="6dp"
+				android:layout_marginRight="6dp"
+				android:textColor="@color/private_message_date_inverse"
+				tools:text="Dec 24, 13:37"/>
+
+			<ImageView
+				android:id="@+id/status"
+				android:layout_width="wrap_content"
+				android:layout_height="wrap_content"
+				tools:ignore="ContentDescription"
+				tools:src="@drawable/message_delivered"/>
+
+		</LinearLayout>
 
 	</android.support.constraint.ConstraintLayout>
 

briar-android/src/main/res/values/color.xml

@@ -40,6 +40,7 @@
 	<color name="msg_stroke_light">#cbcbcb</color>
 	<color name="msg_stroke_dark">#333333</color>
 	<color name="msg_stroke">@color/msg_stroke_light</color>
+	<color name="msg_status_bubble_background">#66000000</color>
 
 	<!-- text colors -->
 	<color name="briar_text_link">@color/briar_blue_light</color>

briar-android/src/main/res/values/dimens.xml

@@ -43,9 +43,18 @@
 	<dimen name="message_bubble_radius_top_inner">@dimen/message_bubble_radius_small</dimen>
 	<dimen name="message_bubble_radius_top_outer">@dimen/message_bubble_radius_big</dimen>
 	<dimen name="message_bubble_margin">6dp</dimen>
+	<dimen name="message_bubble_image_default">210dp</dimen>
+	<dimen name="message_bubble_image_min_width">150dp</dimen>
+	<dimen name="message_bubble_image_max_width">240dp</dimen>
+	<dimen name="message_bubble_image_min_height">100dp</dimen>
+	<dimen name="message_bubble_image_max_height">320dp</dimen>
+	<dimen name="message_bubble_border">2dp</dimen>
 	<dimen name="message_bubble_padding_sides">12dp</dimen>
+	<dimen name="message_bubble_padding_sides_inner">10dp</dimen>
 	<dimen name="message_bubble_padding_top">6dp</dimen>
+	<dimen name="message_bubble_padding_top_inner">4dp</dimen>
 	<dimen name="message_bubble_padding_bottom">4dp</dimen>
+	<dimen name="message_bubble_padding_bottom_inner">2dp</dimen>
 	<dimen name="message_bubble_timestamp_margin">4dp</dimen>
 	<dimen name="message_bubble_elevation">2dp</dimen>
 	<dimen name="message_bubble_margin_tail">8dp</dimen>

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

@@ -134,6 +134,8 @@
 	<string name="dialog_title_delete_contact">Confirm Contact Deletion</string>
 	<string name="dialog_message_delete_contact">Are you sure that you want to remove this contact and all messages exchanged with this contact?</string>
 	<string name="contact_deleted_toast">Contact deleted</string>
+	<!-- This is shown in the action bar when opening an image in fullscreen that the user sent -->
+	<string name="you">You</string>
 
 	<!-- Adding Contacts -->
 	<string name="add_contact_title">Add a Contact</string>

briar-android/src/main/res/values/themes.xml

@@ -18,6 +18,12 @@
 		<item name="toolbarStyle">@style/BriarToolbar</item>
 	</style>
 
+	<style name="BriarTheme.Transparent.NoActionBar" parent="BriarTheme.NoActionBar">
+		<item name="android:windowBackground">@android:color/transparent</item>
+		<item name="android:windowIsTranslucent">true</item>
+		<item name="android:windowActionBarOverlay">true</item>
+	</style>
+
 	<style name="ActivityAnimation" parent="@android:style/Animation.Activity">
 		<item name="android:activityOpenEnterAnimation">@anim/screen_new_in</item>
 		<item name="android:activityOpenExitAnimation">@anim/screen_old_out</item>

briar-android/witness.gradle

@@ -36,6 +36,7 @@ dependencyVerification {
         'com.android.support:design:28.0.0:design-28.0.0.aar:7874ad1904eedc74aa41cffffb7f759d8990056f3bbbc9264911651c67c42f5f',
         'com.android.support:documentfile:28.0.0:documentfile-28.0.0.aar:47cdcd3e9302b7b064923f05487a5c03babbd9bbda4726b71e97791fab5d4779',
         'com.android.support:drawerlayout:28.0.0:drawerlayout-28.0.0.aar:8f6809afae4793550c37461c9810e954ae6a23dbb4d23e5333bf18148df1150a',
+        'com.android.support:exifinterface:28.0.0:exifinterface-28.0.0.aar:bbf44e519edd6333a24a3285aa21fd00181b920b81ca8aa89a8899f03ab4d6b0',
         'com.android.support:interpolator:28.0.0:interpolator-28.0.0.aar:7bc7ee86a0db39a4b51956f3e89842d2bd962118d57d779eb6ed6b34ba0677ea',
         'com.android.support:loader:28.0.0:loader-28.0.0.aar:920b85efd72dc33e915b0f88a883fe73b88483c6df8751a741e17611f2460341',
         'com.android.support:localbroadcastmanager:28.0.0:localbroadcastmanager-28.0.0.aar:d287c823af5fdde72c099fcfc5f630efe9687af7a914343ae6fd92de32c8a806',
@@ -84,6 +85,11 @@ dependencyVerification {
         'com.android.tools:repository:26.2.1:repository-26.2.1.jar:fa74dae09103faef703df38550ad8fa244c5b6d1bf90d6198be932292b3d9cc1',
         'com.android.tools:sdk-common:26.2.1:sdk-common-26.2.1.jar:759d4b292ca69a35cf961fca377b54158fc6c88108978006999442e80a011cf4',
         'com.android.tools:sdklib:26.2.1:sdklib-26.2.1.jar:248df7ad5eac4aeb6f96c394c76760de4b7b89ac056e54d0c21a739368b91b45',
+        'com.github.bumptech.glide:annotations:4.8.0:annotations-4.8.0.jar:4ea82e59874673105165820336c6ac268fc46149892486aad8e7a131a4449446',
+        'com.github.bumptech.glide:compiler:4.8.0:compiler-4.8.0.jar:1fa93dd0cf7ef0b8b98a59a67a1ee84915416c2d677d83a771ea3e32ad15e6bf',
+        'com.github.bumptech.glide:gifdecoder:4.8.0:gifdecoder-4.8.0.aar:b00c5454a023a9488ea49603930d9c25e09192e5ceaadf64977aa52946b3c1b4',
+        'com.github.bumptech.glide:glide:4.8.0:glide-4.8.0.aar:5ddf08b12cc43332e812988f16c2c39e7fce49d1c4d94b7948dcde7f00bf49d6',
+        'com.github.chrisbanes:PhotoView:2.1.4:PhotoView-2.1.4.aar:04cb397fcb3df0757c8aed6927ebdd247930b5c78ee9acc59cd07dccdaaf3460',
         'com.google.android.apps.common.testing.accessibility.framework:accessibility-test-framework:2.0:accessibility-test-framework-2.0.jar:cdf16ef8f5b8023d003ce3cc1b0d51bda737762e2dab2fedf43d1c4292353f7f',
         'com.google.android.apps.common.testing.accessibility.framework:accessibility-test-framework:2.1:accessibility-test-framework-2.1.jar:7b0aa6ed7553597ce0610684a9f7eca8021eee218f2e2f427c04a7fbf5f920bd',
         'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',

briar-api/src/main/java/org/briarproject/briar/api/client/ThreadedMessage.java

@@ -9,6 +9,8 @@ import org.briarproject.briar.api.messaging.PrivateMessage;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
+import static java.util.Collections.emptyList;
+
 @Immutable
 @NotNullByDefault
 public abstract class ThreadedMessage extends PrivateMessage {
@@ -19,7 +21,7 @@ public abstract class ThreadedMessage extends PrivateMessage {
 
 	public ThreadedMessage(Message message, @Nullable MessageId parent,
 			Author author) {
-		super(message);
+		super(message, emptyList());
 		this.parent = parent;
 		this.author = author;
 	}

briar-api/src/main/java/org/briarproject/briar/api/messaging/PrivateMessage.java

@@ -3,6 +3,8 @@ package org.briarproject.briar.api.messaging;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Message;
 
+import java.util.List;
+
 import javax.annotation.concurrent.Immutable;
 
 @Immutable
@@ -10,13 +12,18 @@ import javax.annotation.concurrent.Immutable;
 public class PrivateMessage {
 
 	private final Message message;
+	private final List<AttachmentHeader> attachments;
 
-	public PrivateMessage(Message message) {
+	public PrivateMessage(Message message, List<AttachmentHeader> attachments) {
 		this.message = message;
+		this.attachments = attachments;
 	}
 
 	public Message getMessage() {
 		return message;
 	}
 
+	public List<AttachmentHeader> getAttachmentHeaders() {
+		return attachments;
+	}
 }

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -11,13 +11,16 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.MetadataParser;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.io.MessageInputStreamFactory;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Client;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.Group.Visibility;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
@@ -32,16 +35,17 @@ import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent;
 import org.briarproject.briar.client.ConversationClientImpl;
 
+import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
-import java.util.Random;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static java.util.Collections.emptyList;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_LENGTH;
 import static org.briarproject.briar.client.MessageTrackerConstants.MSG_KEY_READ;
 
 @Immutable
@@ -51,15 +55,21 @@ class MessagingManagerImpl extends ConversationClientImpl
 
 	private final ClientVersioningManager clientVersioningManager;
 	private final ContactGroupFactory contactGroupFactory;
+	private final MessageFactory messageFactory;
+	private final MessageInputStreamFactory messageInputStreamFactory;
 
 	@Inject
 	MessagingManagerImpl(DatabaseComponent db, ClientHelper clientHelper,
 			ClientVersioningManager clientVersioningManager,
 			MetadataParser metadataParser, MessageTracker messageTracker,
-			ContactGroupFactory contactGroupFactory) {
+			ContactGroupFactory contactGroupFactory,
+			MessageFactory messageFactory,
+			MessageInputStreamFactory messageInputStreamFactory) {
 		super(db, clientHelper, metadataParser, messageTracker);
 		this.clientVersioningManager = clientVersioningManager;
 		this.contactGroupFactory = contactGroupFactory;
+		this.messageFactory = messageFactory;
+		this.messageInputStreamFactory = messageInputStreamFactory;
 	}
 
 	@Override
@@ -142,9 +152,11 @@ class MessagingManagerImpl extends ConversationClientImpl
 			meta.put("read", true);
 			clientHelper.addLocalMessage(txn, m.getMessage(), meta, true);
 			messageTracker.trackOutgoingMessage(txn, m.getMessage());
+			for (AttachmentHeader h : m.getAttachmentHeaders())
+				db.setMessageShared(txn, h.getMessageId());
 			db.commitTransaction(txn);
 		} catch (FormatException e) {
-			throw new RuntimeException(e);
+			throw new AssertionError(e);
 		} finally {
 			db.endTransaction(txn);
 		}
@@ -152,11 +164,16 @@ class MessagingManagerImpl extends ConversationClientImpl
 
 	@Override
 	public AttachmentHeader addLocalAttachment(GroupId groupId, long timestamp,
-			String contentType, ByteBuffer data) {
-		// TODO add real implementation
-		byte[] b = new byte[MessageId.LENGTH];
-		new Random().nextBytes(b);
-		return new AttachmentHeader(new MessageId(b), "image/png");
+			String contentType, ByteBuffer data) throws DbException {
+		// TODO: Remove this restriction when large messages are supported
+		byte[] body = data.array();
+		if (body.length > MAX_MESSAGE_LENGTH) throw new DbException();
+		// TODO: Store message type and content type
+		Message m = messageFactory.createMessage(groupId, timestamp, body);
+		Metadata meta = new Metadata();
+		// Attachment will be shared when private message is added
+		db.transaction(false, txn -> db.addLocalMessage(txn, m, meta, false));
+		return new AttachmentHeader(m.getId(), contentType);
 	}
 
 	private ContactId getContactId(Transaction txn, GroupId g)
@@ -236,8 +253,9 @@ class MessagingManagerImpl extends ConversationClientImpl
 
 	@Override
 	public Attachment getAttachment(MessageId m) {
-		// TODO add real implementation
-		throw new IllegalStateException("Not yet implemented");
+		InputStream in = messageInputStreamFactory.getMessageInputStream(m);
+		// TODO: Read message type and content type
+		return new Attachment(in);
 	}
 
 }

briar-core/src/main/java/org/briarproject/briar/messaging/PrivateMessageFactoryImpl.java

@@ -39,6 +39,6 @@ class PrivateMessageFactoryImpl implements PrivateMessageFactory {
 		// Serialise the message
 		BdfList message = BdfList.of(text);
 		Message m = clientHelper.createMessage(groupId, timestamp, message);
-		return new PrivateMessage(m);
+		return new PrivateMessage(m, attachments);
 	}
 }

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTestComponent.java

@@ -8,6 +8,7 @@ import org.briarproject.bramble.data.DataModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.record.RecordModule;
@@ -50,6 +51,7 @@ import dagger.Component;
 		GroupInvitationModule.class,
 		IdentityModule.class,
 		IntroductionModule.class,
+		IoModule.class,
 		LifecycleModule.class,
 		MessagingModule.class,
 		PrivateGroupModule.class,

briar-core/src/test/java/org/briarproject/briar/messaging/MessageSizeIntegrationTestComponent.java

@@ -8,6 +8,7 @@ import org.briarproject.bramble.data.DataModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.system.SystemModule;
@@ -40,6 +41,7 @@ import dagger.Component;
 		EventModule.class,
 		ForumModule.class,
 		IdentityModule.class,
+		IoModule.class,
 		MessagingModule.class,
 		SyncModule.class,
 		SystemModule.class,

briar-core/src/test/java/org/briarproject/briar/messaging/SimplexMessagingIntegrationTestComponent.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.data.DataModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.record.RecordModule;
 import org.briarproject.bramble.sync.SyncModule;
@@ -48,6 +49,7 @@ import dagger.Component;
 		DatabaseModule.class,
 		EventModule.class,
 		IdentityModule.class,
+		IoModule.class,
 		LifecycleModule.class,
 		MessagingModule.class,
 		RecordModule.class,

briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTestComponent.java

@@ -17,6 +17,7 @@ import org.briarproject.bramble.data.DataModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.record.RecordModule;
@@ -68,6 +69,7 @@ import dagger.Component;
 		GroupInvitationModule.class,
 		IdentityModule.class,
 		IntroductionModule.class,
+		IoModule.class,
 		LifecycleModule.class,
 		MessagingModule.class,
 		PrivateGroupModule.class,

briar-headless/src/main/java/org/briarproject/briar/headless/HeadlessModule.kt

@@ -24,8 +24,10 @@ import org.briarproject.bramble.battery.DefaultBatteryManagerModule
 import org.briarproject.bramble.network.JavaNetworkModule
 import org.briarproject.bramble.plugin.tor.CircumventionModule
 import org.briarproject.bramble.plugin.tor.CircumventionProvider
-import org.briarproject.bramble.plugin.tor.LinuxTorPluginFactory
+import org.briarproject.bramble.plugin.tor.UnixTorPluginFactory
 import org.briarproject.bramble.system.JavaSystemModule
+import org.briarproject.bramble.util.OsUtils.isLinux
+import org.briarproject.bramble.util.OsUtils.isMac
 import org.briarproject.bramble.util.StringUtils.fromHexString
 import org.briarproject.briar.headless.blogs.HeadlessBlogModule
 import org.briarproject.briar.headless.contact.HeadlessContactModule
@@ -70,11 +72,17 @@ internal class HeadlessModule(private val appDir: File) {
         circumventionProvider: CircumventionProvider, batteryManager: BatteryManager, clock: Clock
     ): PluginConfig {
         val torDirectory = File(appDir, "tor")
-        val tor = LinuxTorPluginFactory(
-            ioExecutor, networkManager, locationUtils, eventBus, torSocketFactory, backoffFactory,
-            resourceProvider, circumventionProvider, batteryManager, clock, torDirectory
-        )
-        val duplex = listOf<DuplexPluginFactory>(tor)
+        val duplex: List<DuplexPluginFactory>
+        if (isLinux() || isMac()) {
+            val tor = UnixTorPluginFactory(
+                ioExecutor, networkManager, locationUtils, eventBus, torSocketFactory,
+                backoffFactory, resourceProvider, circumventionProvider, batteryManager, clock,
+                torDirectory
+            )
+            duplex = listOf(tor)
+        } else {
+            duplex = emptyList()
+        }
         return object : PluginConfig {
             override fun getDuplexFactories(): Collection<DuplexPluginFactory> {
                 return duplex

briar-headless/src/test/java/org/briarproject/briar/headless/messaging/MessagingControllerImplTest.kt

@@ -62,7 +62,7 @@ internal class MessagingControllerImplTest : ControllerTest() {
             emptyList()
         )
     private val sessionId = SessionId(getRandomId())
-    private val privateMessage = PrivateMessage(message)
+    private val privateMessage = PrivateMessage(message, emptyList())
 
     @Test
     fun list() {

build.gradle

@@ -5,6 +5,7 @@ allprojects {
 		jcenter()
 		mavenLocal()
 		google()
+		maven { url "https://jitpack.io" }
 	}
 	afterEvaluate {
 		tasks.withType(Test) {