Merge branch 'merge-handshake-and-transport-keys' into 'master'

Add support for handshake keys to KeyManager

See merge request briar/briar!1088

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

@@ -4,7 +4,6 @@ import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -42,7 +41,7 @@ class TransportCryptoImpl implements TransportCrypto {
 	}
 
 	@Override
-	public TransportKeys deriveTransportKeys(TransportId t,
+	public TransportKeys deriveRotationKeys(TransportId t,
 			SecretKey rootKey, long timePeriod, boolean weAreAlice,
 			boolean active) {
 		// Keys for the previous period are derived from the root key
@@ -70,31 +69,6 @@ class TransportCryptoImpl implements TransportCrypto {
 		return new TransportKeys(t, inPrev, inCurr, inNext, outCurr);
 	}
 
-	@Override
-	public TransportKeys rotateTransportKeys(TransportKeys k, long timePeriod) {
-		if (k.getTimePeriod() >= timePeriod) return k;
-		IncomingKeys inPrev = k.getPreviousIncomingKeys();
-		IncomingKeys inCurr = k.getCurrentIncomingKeys();
-		IncomingKeys inNext = k.getNextIncomingKeys();
-		OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
-		long startPeriod = outCurr.getTimePeriod();
-		boolean active = outCurr.isActive();
-		// Rotate the keys
-		for (long p = startPeriod + 1; p <= timePeriod; p++) {
-			inPrev = inCurr;
-			inCurr = inNext;
-			SecretKey inNextTag = rotateKey(inNext.getTagKey(), p + 1);
-			SecretKey inNextHeader = rotateKey(inNext.getHeaderKey(), p + 1);
-			inNext = new IncomingKeys(inNextTag, inNextHeader, p + 1);
-			SecretKey outCurrTag = rotateKey(outCurr.getTagKey(), p);
-			SecretKey outCurrHeader = rotateKey(outCurr.getHeaderKey(), p);
-			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p, active);
-		}
-		// Collect and return the keys
-		return new TransportKeys(k.getTransportId(), inPrev, inCurr, inNext,
-				outCurr);
-	}
-
 	private SecretKey rotateKey(SecretKey k, long timePeriod) {
 		byte[] period = new byte[INT_64_BYTES];
 		writeUint64(timePeriod, period, 0);
@@ -117,7 +91,7 @@ class TransportCryptoImpl implements TransportCrypto {
 	}
 
 	@Override
-	public HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
+	public TransportKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
 			long timePeriod, boolean weAreAlice) {
 		if (timePeriod < 1) throw new IllegalArgumentException();
 		IncomingKeys inPrev = deriveIncomingHandshakeKeys(t, rootKey,
@@ -128,7 +102,7 @@ class TransportCryptoImpl implements TransportCrypto {
 				weAreAlice, timePeriod + 1);
 		OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
 				weAreAlice, timePeriod);
-		return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, rootKey,
+		return new TransportKeys(t, inPrev, inCurr, inNext, outCurr, rootKey,
 				weAreAlice);
 	}
 
@@ -171,7 +145,13 @@ class TransportCryptoImpl implements TransportCrypto {
 	}
 
 	@Override
-	public HandshakeKeys updateHandshakeKeys(HandshakeKeys k, long timePeriod) {
+	public TransportKeys updateTransportKeys(TransportKeys k, long timePeriod) {
+		if (k.isHandshakeMode()) return updateHandshakeKeys(k, timePeriod);
+		else return updateRotationKeys(k, timePeriod);
+	}
+
+	private TransportKeys updateHandshakeKeys(TransportKeys k,
+			long timePeriod) {
 		long elapsed = timePeriod - k.getTimePeriod();
 		TransportId t = k.getTransportId();
 		SecretKey rootKey = k.getRootKey();
@@ -188,7 +168,7 @@ class TransportCryptoImpl implements TransportCrypto {
 					weAreAlice, timePeriod + 1);
 			OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
 					weAreAlice, timePeriod);
-			return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
+			return new TransportKeys(t, inPrev, inCurr, inNext, outCurr,
 					rootKey, weAreAlice);
 		} else if (elapsed == 2) {
 			// The keys are two periods old - shift by two periods, keeping
@@ -200,7 +180,7 @@ class TransportCryptoImpl implements TransportCrypto {
 					weAreAlice, timePeriod + 1);
 			OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
 					weAreAlice, timePeriod);
-			return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
+			return new TransportKeys(t, inPrev, inCurr, inNext, outCurr,
 					rootKey, weAreAlice);
 		} else {
 			// The keys are more than two periods old - derive fresh keys
@@ -208,6 +188,30 @@ class TransportCryptoImpl implements TransportCrypto {
 		}
 	}
 
+	private TransportKeys updateRotationKeys(TransportKeys k, long timePeriod) {
+		if (k.getTimePeriod() >= timePeriod) return k;
+		IncomingKeys inPrev = k.getPreviousIncomingKeys();
+		IncomingKeys inCurr = k.getCurrentIncomingKeys();
+		IncomingKeys inNext = k.getNextIncomingKeys();
+		OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
+		long startPeriod = outCurr.getTimePeriod();
+		boolean active = outCurr.isActive();
+		// Rotate the keys
+		for (long p = startPeriod + 1; p <= timePeriod; p++) {
+			inPrev = inCurr;
+			inCurr = inNext;
+			SecretKey inNextTag = rotateKey(inNext.getTagKey(), p + 1);
+			SecretKey inNextHeader = rotateKey(inNext.getHeaderKey(), p + 1);
+			inNext = new IncomingKeys(inNextTag, inNextHeader, p + 1);
+			SecretKey outCurrTag = rotateKey(outCurr.getTagKey(), p);
+			SecretKey outCurrHeader = rotateKey(outCurr.getHeaderKey(), p);
+			outCurr = new OutgoingKeys(outCurrTag, outCurrHeader, p, active);
+		}
+		// Collect and return the keys
+		return new TransportKeys(k.getTransportId(), inPrev, inCurr, inNext,
+				outCurr);
+	}
+
 	@Override
 	public void encodeTag(byte[] tag, SecretKey tagKey, int protocolVersion,
 			long streamNumber) {

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

@@ -29,11 +29,8 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.validation.MessageState;
-import org.briarproject.bramble.api.transport.HandshakeKeySet;
-import org.briarproject.bramble.api.transport.HandshakeKeySetId;
-import org.briarproject.bramble.api.transport.HandshakeKeys;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeySet;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
@@ -107,20 +104,6 @@ interface Database<T> {
 	void addGroupVisibility(T txn, ContactId c, GroupId g, boolean shared)
 			throws DbException;
 
-	/**
-	 * Stores the given handshake keys for the given contact and returns a
-	 * key set ID.
-	 */
-	HandshakeKeySetId addHandshakeKeys(T txn, ContactId c, HandshakeKeys k)
-			throws DbException;
-
-	/**
-	 * Stores the given handshake keys for the given pending contact and
-	 * returns a key set ID.
-	 */
-	HandshakeKeySetId addHandshakeKeys(T txn, PendingContactId p,
-			HandshakeKeys k) throws DbException;
-
 	/**
 	 * Stores an identity.
 	 */
@@ -162,7 +145,14 @@ interface Database<T> {
 	 * Stores the given transport keys for the given contact and returns a
 	 * key set ID.
 	 */
-	TransportKeySetId addTransportKeys(T txn, ContactId c, TransportKeys k)
+	KeySetId addTransportKeys(T txn, ContactId c, TransportKeys k)
+			throws DbException;
+
+	/**
+	 * Stores the given transport keys for the given pending contact and
+	 * returns a key set ID.
+	 */
+	KeySetId addTransportKeys(T txn, PendingContactId p, TransportKeys k)
 			throws DbException;
 
 	/**
@@ -275,7 +265,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<ContactId> getContacts(T txn, AuthorId a) throws DbException;
+	Collection<ContactId> getContacts(T txn, AuthorId local) throws DbException;
 
 	/**
 	 * Returns the group with the given ID.
@@ -317,14 +307,6 @@ interface Database<T> {
 	Map<ContactId, Boolean> getGroupVisibility(T txn, GroupId g)
 			throws DbException;
 
-	/**
-	 * Returns all handshake keys for the given transport.
-	 * <p/>
-	 * Read-only.
-	 */
-	Collection<HandshakeKeySet> getHandshakeKeys(T txn, TransportId t)
-			throws DbException;
-
 	/**
 	 * Returns the identity for local pseudonym with the given ID.
 	 * <p/>
@@ -547,16 +529,10 @@ interface Database<T> {
 	Collection<TransportKeySet> getTransportKeys(T txn, TransportId t)
 			throws DbException;
 
-	/**
-	 * Increments the outgoing stream counter for the given handshake keys.
-	 */
-	void incrementStreamCounter(T txn, TransportId t, HandshakeKeySetId k)
-			throws DbException;
-
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
-	void incrementStreamCounter(T txn, TransportId t, TransportKeySetId k)
+	void incrementStreamCounter(T txn, TransportId t, KeySetId k)
 			throws DbException;
 
 	/**
@@ -625,12 +601,6 @@ interface Database<T> {
 	void removeGroupVisibility(T txn, ContactId c, GroupId g)
 			throws DbException;
 
-	/**
-	 * Removes the given handshake keys from the database.
-	 */
-	void removeHandshakeKeys(T txn, TransportId t, HandshakeKeySetId k)
-			throws DbException;
-
 	/**
 	 * Removes an identity (and all associated state) from the database.
 	 */
@@ -661,8 +631,7 @@ interface Database<T> {
 	/**
 	 * Removes the given transport keys from the database.
 	 */
-	void removeTransportKeys(T txn, TransportId t, TransportKeySetId k)
-			throws DbException;
+	void removeTransportKeys(T txn, TransportId t, KeySetId k) throws DbException;
 
 	/**
 	 * Resets the transmission count and expiry time of the given message with
@@ -712,23 +681,16 @@ interface Database<T> {
 			PendingContactState state) throws DbException;
 
 	/**
-	 * Sets the reordering window for the given transport key set in the given
+	 * Sets the reordering window for the given transport keys in the given
 	 * time period.
 	 */
-	void setReorderingWindow(T txn, TransportKeySetId k, TransportId t,
-			long timePeriod, long base, byte[] bitmap) throws DbException;
-
-	/**
-	 * Sets the reordering window for the given handshake key set in the given
-	 * time period.
-	 */
-	void setReorderingWindow(T txn, HandshakeKeySetId k, TransportId t,
+	void setReorderingWindow(T txn, KeySetId k, TransportId t,
 			long timePeriod, long base, byte[] bitmap) throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
-	void setTransportKeysActive(T txn, TransportId t, TransportKeySetId k)
+	void setTransportKeysActive(T txn, TransportId t, KeySetId k)
 			throws DbException;
 
 	/**
@@ -740,12 +702,7 @@ interface Database<T> {
 			throws DbException;
 
 	/**
-	 * Updates the given handshake keys.
-	 */
-	void updateHandshakeKeys(T txn, HandshakeKeySet ks) throws DbException;
-
-	/**
-	 * Updates the given transport keys following key rotation.
+	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
 	void updateTransportKeys(T txn, TransportKeySet ks) throws DbException;
 }

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

@@ -64,11 +64,8 @@ import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
 import org.briarproject.bramble.api.sync.validation.MessageState;
-import org.briarproject.bramble.api.transport.HandshakeKeySet;
-import org.briarproject.bramble.api.transport.HandshakeKeySetId;
-import org.briarproject.bramble.api.transport.HandshakeKeys;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeySet;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.ArrayList;
@@ -260,30 +257,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		}
 	}
 
-	@Override
-	public HandshakeKeySetId addHandshakeKeys(Transaction transaction,
-			ContactId c, HandshakeKeys k) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsContact(txn, c))
-			throw new NoSuchContactException();
-		if (!db.containsTransport(txn, k.getTransportId()))
-			throw new NoSuchTransportException();
-		return db.addHandshakeKeys(txn, c, k);
-	}
-
-	@Override
-	public HandshakeKeySetId addHandshakeKeys(Transaction transaction,
-			PendingContactId p, HandshakeKeys k) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsPendingContact(txn, p))
-			throw new NoSuchPendingContactException();
-		if (!db.containsTransport(txn, k.getTransportId()))
-			throw new NoSuchTransportException();
-		return db.addHandshakeKeys(txn, p, k);
-	}
-
 	@Override
 	public void addIdentity(Transaction transaction, Identity i)
 			throws DbException {
@@ -332,8 +305,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public TransportKeySetId addTransportKeys(Transaction transaction,
-			ContactId c, TransportKeys k) throws DbException {
+	public KeySetId addTransportKeys(Transaction transaction, ContactId c,
+			TransportKeys k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
@@ -343,6 +316,18 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.addTransportKeys(txn, c, k);
 	}
 
+	@Override
+	public KeySetId addTransportKeys(Transaction transaction,
+			PendingContactId p, TransportKeys k) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsPendingContact(txn, p))
+			throw new NoSuchPendingContactException();
+		if (!db.containsTransport(txn, k.getTransportId()))
+			throw new NoSuchTransportException();
+		return db.addTransportKeys(txn, p, k);
+	}
+
 	@Override
 	public boolean containsContact(Transaction transaction, AuthorId remote,
 			AuthorId local) throws DbException {
@@ -505,11 +490,11 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public Collection<ContactId> getContacts(Transaction transaction,
-			AuthorId a) throws DbException {
+			AuthorId local) throws DbException {
 		T txn = unbox(transaction);
-		if (!db.containsIdentity(txn, a))
+		if (!db.containsIdentity(txn, local))
 			throw new NoSuchIdentityException();
-		return db.getContacts(txn, a);
+		return db.getContacts(txn, local);
 	}
 
 	@Override
@@ -546,15 +531,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getGroupVisibility(txn, c, g);
 	}
 
-	@Override
-	public Collection<HandshakeKeySet> getHandshakeKeys(Transaction transaction,
-			TransportId t) throws DbException {
-		T txn = unbox(transaction);
-		if (!db.containsTransport(txn, t))
-			throw new NoSuchTransportException();
-		return db.getHandshakeKeys(txn, t);
-	}
-
 	@Override
 	public Identity getIdentity(Transaction transaction, AuthorId a)
 			throws DbException {
@@ -737,17 +713,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void incrementStreamCounter(Transaction transaction, TransportId t,
-			HandshakeKeySetId k) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsTransport(txn, t))
-			throw new NoSuchTransportException();
-		db.incrementStreamCounter(txn, t, k);
-	}
-
-	@Override
-	public void incrementStreamCounter(Transaction transaction, TransportId t,
-			TransportKeySetId k) throws DbException {
+			KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
@@ -896,16 +862,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
 	}
 
-	@Override
-	public void removeHandshakeKeys(Transaction transaction,
-			TransportId t, HandshakeKeySetId k) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsTransport(txn, t))
-			throw new NoSuchTransportException();
-		db.removeHandshakeKeys(txn, t, k);
-	}
-
 	@Override
 	public void removeIdentity(Transaction transaction, AuthorId a)
 			throws DbException {
@@ -949,8 +905,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public void removeTransportKeys(Transaction transaction,
-			TransportId t, TransportKeySetId k) throws DbException {
+	public void removeTransportKeys(Transaction transaction, TransportId t,
+			KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
@@ -1048,20 +1004,9 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public void setReorderingWindow(Transaction transaction,
-			TransportKeySetId k, TransportId t, long timePeriod, long base,
-			byte[] bitmap) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsTransport(txn, t))
-			throw new NoSuchTransportException();
-		db.setReorderingWindow(txn, k, t, timePeriod, base, bitmap);
-	}
-
-	@Override
-	public void setReorderingWindow(Transaction transaction,
-			HandshakeKeySetId k, TransportId t, long timePeriod, long base,
-			byte[] bitmap) throws DbException {
+	public void setReorderingWindow(Transaction transaction, KeySetId k,
+			TransportId t, long timePeriod, long base, byte[] bitmap)
+			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
@@ -1071,7 +1016,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void setTransportKeysActive(Transaction transaction, TransportId t,
-			TransportKeySetId k) throws DbException {
+			KeySetId k) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
@@ -1079,18 +1024,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setTransportKeysActive(txn, t, k);
 	}
 
-	@Override
-	public void updateHandshakeKeys(Transaction transaction,
-			Collection<HandshakeKeySet> keys) throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		for (HandshakeKeySet ks : keys) {
-			TransportId t = ks.getKeys().getTransportId();
-			if (db.containsTransport(txn, t))
-				db.updateHandshakeKeys(txn, ks);
-		}
-	}
-
 	@Override
 	public void updateTransportKeys(Transaction transaction,
 			Collection<TransportKeySet> keys) throws DbException {

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

@@ -36,13 +36,10 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.api.transport.HandshakeKeySet;
-import org.briarproject.bramble.api.transport.HandshakeKeySetId;
-import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.IncomingKeys;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeySet;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.sql.Connection;
@@ -68,11 +65,13 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 
 import static java.sql.Types.BINARY;
+import static java.sql.Types.BOOLEAN;
 import static java.sql.Types.INTEGER;
 import static java.sql.Types.VARCHAR;
 import static java.util.Arrays.asList;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -99,7 +98,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 43;
+	static final int CODE_SCHEMA_VERSION = 44;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -260,16 +259,28 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " maxLatency INT NOT NULL,"
 					+ " PRIMARY KEY (transportId))";
 
+	private static final String CREATE_PENDING_CONTACTS =
+			"CREATE TABLE pendingContacts"
+					+ " (pendingContactId _HASH NOT NULL,"
+					+ " publicKey _BINARY NOT NULL,"
+					+ " alias _STRING NOT NULL,"
+					+ " state INT NOT NULL,"
+					+ " timestamp BIGINT NOT NULL,"
+					+ " PRIMARY KEY (pendingContactId))";
+
 	private static final String CREATE_OUTGOING_KEYS =
 			"CREATE TABLE outgoingKeys"
 					+ " (transportId _STRING NOT NULL,"
 					+ " keySetId _COUNTER,"
 					+ " timePeriod BIGINT NOT NULL,"
-					+ " contactId INT NOT NULL,"
+					+ " contactId INT," // Null if contact is pending
+					+ " pendingContactId _HASH," // Null if not pending
 					+ " tagKey _SECRET NOT NULL,"
 					+ " headerKey _SECRET NOT NULL,"
 					+ " stream BIGINT NOT NULL,"
 					+ " active BOOLEAN NOT NULL,"
+					+ " rootKey _SECRET," // Null for rotation keys
+					+ " alice BOOLEAN," // Null for rotation keys
 					+ " PRIMARY KEY (transportId, keySetId),"
 					+ " FOREIGN KEY (transportId)"
 					+ " REFERENCES transports (transportId)"
@@ -277,6 +288,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " UNIQUE (keySetId),"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
+					+ " ON DELETE CASCADE,"
+					+ " FOREIGN KEY (pendingContactId)"
+					+ " REFERENCES pendingContacts (pendingContactId)"
 					+ " ON DELETE CASCADE)";
 
 	private static final String CREATE_INCOMING_KEYS =
@@ -297,57 +311,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " REFERENCES outgoingKeys (keySetId)"
 					+ " ON DELETE CASCADE)";
 
-	private static final String CREATE_PENDING_CONTACTS =
-			"CREATE TABLE pendingContacts"
-					+ " (pendingContactId _HASH NOT NULL,"
-					+ " publicKey _BINARY NOT NULL,"
-					+ " alias _STRING NOT NULL,"
-					+ " state INT NOT NULL,"
-					+ " timestamp BIGINT NOT NULL,"
-					+ " PRIMARY KEY (pendingContactId))";
-
-	private static final String CREATE_OUTGOING_HANDSHAKE_KEYS =
-			"CREATE TABLE outgoingHandshakeKeys"
-					+ " (transportId _STRING NOT NULL,"
-					+ " keySetId _COUNTER,"
-					+ " timePeriod BIGINT NOT NULL,"
-					+ " contactId INT," // Null if contact is pending
-					+ " pendingContactId _HASH," // Null if not pending
-					+ " rootKey _SECRET NOT NULL,"
-					+ " alice BOOLEAN NOT NULL,"
-					+ " tagKey _SECRET NOT NULL,"
-					+ " headerKey _SECRET NOT NULL,"
-					+ " stream BIGINT NOT NULL,"
-					+ " PRIMARY KEY (transportId, keySetId),"
-					+ " FOREIGN KEY (transportId)"
-					+ " REFERENCES transports (transportId)"
-					+ " ON DELETE CASCADE,"
-					+ " UNIQUE (keySetId),"
-					+ " FOREIGN KEY (contactId)"
-					+ " REFERENCES contacts (contactId)"
-					+ " ON DELETE CASCADE,"
-					+ " FOREIGN KEY (pendingContactId)"
-					+ " REFERENCES pendingContacts (pendingContactId)"
-					+ " ON DELETE CASCADE)";
-
-	private static final String CREATE_INCOMING_HANDSHAKE_KEYS =
-			"CREATE TABLE incomingHandshakeKeys"
-					+ " (transportId _STRING NOT NULL,"
-					+ " keySetId INT NOT NULL,"
-					+ " timePeriod BIGINT NOT NULL,"
-					+ " tagKey _SECRET NOT NULL,"
-					+ " headerKey _SECRET NOT NULL,"
-					+ " base BIGINT NOT NULL,"
-					+ " bitmap _BINARY NOT NULL,"
-					+ " periodOffset INT NOT NULL,"
-					+ " PRIMARY KEY (transportId, keySetId, periodOffset),"
-					+ " FOREIGN KEY (transportId)"
-					+ " REFERENCES transports (transportId)"
-					+ " ON DELETE CASCADE,"
-					+ " FOREIGN KEY (keySetId)"
-					+ " REFERENCES outgoingHandshakeKeys (keySetId)"
-					+ " ON DELETE CASCADE)";
-
 	private static final String INDEX_CONTACTS_BY_AUTHOR_ID =
 			"CREATE INDEX IF NOT EXISTS contactsByAuthorId"
 					+ " ON contacts (authorId)";
@@ -373,7 +336,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " ON statuses (contactId, timestamp)";
 
 	private static final Logger LOG =
-			Logger.getLogger(JdbcDatabase.class.getName());
+			getLogger(JdbcDatabase.class.getName());
 
 	// Different database libraries use different names for certain types
 	private final MessageFactory messageFactory;
@@ -493,7 +456,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration39_40(),
 				new Migration40_41(dbTypes),
 				new Migration41_42(dbTypes),
-				new Migration42_43(dbTypes)
+				new Migration42_43(dbTypes),
+				new Migration43_44(dbTypes)
 		);
 	}
 
@@ -541,13 +505,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_OFFERS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_STATUSES));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_TRANSPORTS));
+			s.executeUpdate(dbTypes.replaceTypes(CREATE_PENDING_CONTACTS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_OUTGOING_KEYS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_INCOMING_KEYS));
-			s.executeUpdate(dbTypes.replaceTypes(CREATE_PENDING_CONTACTS));
-			s.executeUpdate(dbTypes.replaceTypes(
-					CREATE_OUTGOING_HANDSHAKE_KEYS));
-			s.executeUpdate(dbTypes.replaceTypes(
-					CREATE_INCOMING_HANDSHAKE_KEYS));
 			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
@@ -783,103 +743,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public HandshakeKeySetId addHandshakeKeys(Connection txn, ContactId c,
-			HandshakeKeys k) throws DbException {
-		return addHandshakeKeys(txn, c, null, k);
-	}
-
-	@Override
-	public HandshakeKeySetId addHandshakeKeys(Connection txn,
-			PendingContactId p, HandshakeKeys k) throws DbException {
-		return addHandshakeKeys(txn, null, p, k);
-	}
-
-	private HandshakeKeySetId addHandshakeKeys(Connection txn,
-			@Nullable ContactId c, @Nullable PendingContactId p,
-			HandshakeKeys k) throws DbException {
-		PreparedStatement ps = null;
-		ResultSet rs = null;
-		try {
-			// Store the outgoing keys
-			String sql = "INSERT INTO outgoingHandshakeKeys (contactId,"
-					+ " pendingContactId, transportId, rootKey, alice,"
-					+ " timePeriod, tagKey, headerKey, stream)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)";
-			ps = txn.prepareStatement(sql);
-			if (c == null) ps.setNull(1, INTEGER);
-			else ps.setInt(1, c.getInt());
-			if (p == null) ps.setNull(2, BINARY);
-			else ps.setBytes(2, p.getBytes());
-			ps.setString(3, k.getTransportId().getString());
-			ps.setBytes(4, k.getRootKey().getBytes());
-			ps.setBoolean(5, k.isAlice());
-			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
-			ps.setLong(6, outCurr.getTimePeriod());
-			ps.setBytes(7, outCurr.getTagKey().getBytes());
-			ps.setBytes(8, outCurr.getHeaderKey().getBytes());
-			ps.setLong(9, outCurr.getStreamCounter());
-			int affected = ps.executeUpdate();
-			if (affected != 1) throw new DbStateException();
-			ps.close();
-			// Get the new (highest) key set ID
-			sql = "SELECT keySetId FROM outgoingHandshakeKeys"
-					+ " ORDER BY keySetId DESC LIMIT 1";
-			ps = txn.prepareStatement(sql);
-			rs = ps.executeQuery();
-			if (!rs.next()) throw new DbStateException();
-			HandshakeKeySetId keySetId = new HandshakeKeySetId(rs.getInt(1));
-			if (rs.next()) throw new DbStateException();
-			rs.close();
-			ps.close();
-			// Store the incoming keys
-			sql = "INSERT INTO incomingHandshakeKeys (keySetId, transportId,"
-					+ " timePeriod, tagKey, headerKey, base, bitmap,"
-					+ " periodOffset)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
-			ps = txn.prepareStatement(sql);
-			ps.setInt(1, keySetId.getInt());
-			ps.setString(2, k.getTransportId().getString());
-			// Previous time period
-			IncomingKeys inPrev = k.getPreviousIncomingKeys();
-			ps.setLong(3, inPrev.getTimePeriod());
-			ps.setBytes(4, inPrev.getTagKey().getBytes());
-			ps.setBytes(5, inPrev.getHeaderKey().getBytes());
-			ps.setLong(6, inPrev.getWindowBase());
-			ps.setBytes(7, inPrev.getWindowBitmap());
-			ps.setInt(8, OFFSET_PREV);
-			ps.addBatch();
-			// Current time period
-			IncomingKeys inCurr = k.getCurrentIncomingKeys();
-			ps.setLong(3, inCurr.getTimePeriod());
-			ps.setBytes(4, inCurr.getTagKey().getBytes());
-			ps.setBytes(5, inCurr.getHeaderKey().getBytes());
-			ps.setLong(6, inCurr.getWindowBase());
-			ps.setBytes(7, inCurr.getWindowBitmap());
-			ps.setInt(8, OFFSET_CURR);
-			ps.addBatch();
-			// Next time period
-			IncomingKeys inNext = k.getNextIncomingKeys();
-			ps.setLong(3, inNext.getTimePeriod());
-			ps.setBytes(4, inNext.getTagKey().getBytes());
-			ps.setBytes(5, inNext.getHeaderKey().getBytes());
-			ps.setLong(6, inNext.getWindowBase());
-			ps.setBytes(7, inNext.getWindowBitmap());
-			ps.setInt(8, OFFSET_NEXT);
-			ps.addBatch();
-			int[] batchAffected = ps.executeBatch();
-			if (batchAffected.length != 3) throw new DbStateException();
-			for (int rows : batchAffected)
-				if (rows != 1) throw new DbStateException();
-			ps.close();
-			return keySetId;
-		} catch (SQLException e) {
-			tryToClose(rs, LOG, WARNING);
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
 	@Override
 	public void addIdentity(Connection txn, Identity i) throws DbException {
 		PreparedStatement ps = null;
@@ -1107,24 +970,47 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public TransportKeySetId addTransportKeys(Connection txn, ContactId c,
+	public KeySetId addTransportKeys(Connection txn, ContactId c,
+			TransportKeys k) throws DbException {
+		return addTransportKeys(txn, c, null, k);
+	}
+
+	@Override
+	public KeySetId addTransportKeys(Connection txn,
+			PendingContactId p, TransportKeys k) throws DbException {
+		return addTransportKeys(txn, null, p, k);
+	}
+
+	private KeySetId addTransportKeys(Connection txn,
+			@Nullable ContactId c, @Nullable PendingContactId p,
 			TransportKeys k) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
 			// Store the outgoing keys
-			String sql = "INSERT INTO outgoingKeys (contactId, transportId,"
-					+ " timePeriod, tagKey, headerKey, stream, active)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
+			String sql = "INSERT INTO outgoingKeys (transportId, timePeriod,"
+					+ " contactId, pendingContactId, tagKey, headerKey,"
+					+ " stream, active, rootKey, alice)"
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
-			ps.setInt(1, c.getInt());
-			ps.setString(2, k.getTransportId().getString());
+			ps.setString(1, k.getTransportId().getString());
+			ps.setLong(2, k.getTimePeriod());
+			if (c == null) ps.setNull(3, INTEGER);
+			else ps.setInt(3, c.getInt());
+			if (p == null) ps.setNull(4, BINARY);
+			else ps.setBytes(4, p.getBytes());
 			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
-			ps.setLong(3, outCurr.getTimePeriod());
-			ps.setBytes(4, outCurr.getTagKey().getBytes());
-			ps.setBytes(5, outCurr.getHeaderKey().getBytes());
-			ps.setLong(6, outCurr.getStreamCounter());
-			ps.setBoolean(7, outCurr.isActive());
+			ps.setBytes(5, outCurr.getTagKey().getBytes());
+			ps.setBytes(6, outCurr.getHeaderKey().getBytes());
+			ps.setLong(7, outCurr.getStreamCounter());
+			ps.setBoolean(8, outCurr.isActive());
+			if (k.isHandshakeMode()) {
+				ps.setBytes(9, k.getRootKey().getBytes());
+				ps.setBoolean(10, k.isAlice());
+			} else {
+				ps.setNull(9, BINARY);
+				ps.setNull(10, BOOLEAN);
+			}
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -1134,18 +1020,18 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps = txn.prepareStatement(sql);
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
-			TransportKeySetId keySetId = new TransportKeySetId(rs.getInt(1));
+			KeySetId keySetId = new KeySetId(rs.getInt(1));
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
 			// Store the incoming keys
-			sql = "INSERT INTO incomingKeys (keySetId, transportId,"
+			sql = "INSERT INTO incomingKeys (transportId, keySetId,"
 					+ " timePeriod, tagKey, headerKey, base, bitmap,"
 					+ " periodOffset)"
 					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
-			ps.setInt(1, keySetId.getInt());
-			ps.setString(2, k.getTransportId().getString());
+			ps.setString(1, k.getTransportId().getString());
+			ps.setInt(2, keySetId.getInt());
 			// Previous time period
 			IncomingKeys inPrev = k.getPreviousIncomingKeys();
 			ps.setLong(3, inPrev.getTimePeriod());
@@ -1673,86 +1559,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public Collection<HandshakeKeySet> getHandshakeKeys(Connection txn,
-			TransportId t) throws DbException {
-		PreparedStatement ps = null;
-		ResultSet rs = null;
-		try {
-			// Retrieve the incoming keys
-			String sql = "SELECT timePeriod, tagKey, headerKey, base, bitmap"
-					+ " FROM incomingHandshakeKeys"
-					+ " WHERE transportId = ?"
-					+ " ORDER BY keySetId, periodOffset";
-			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
-			rs = ps.executeQuery();
-			List<IncomingKeys> inKeys = new ArrayList<>();
-			while (rs.next()) {
-				long timePeriod = rs.getLong(1);
-				SecretKey tagKey = new SecretKey(rs.getBytes(2));
-				SecretKey headerKey = new SecretKey(rs.getBytes(3));
-				long windowBase = rs.getLong(4);
-				byte[] windowBitmap = rs.getBytes(5);
-				inKeys.add(new IncomingKeys(tagKey, headerKey, timePeriod,
-						windowBase, windowBitmap));
-			}
-			rs.close();
-			ps.close();
-			// Retrieve the outgoing keys in the same order
-			sql = "SELECT keySetId, contactId, pendingContactId, timePeriod,"
-					+ " tagKey, headerKey, rootKey, alice, stream"
-					+ " FROM outgoingHandshakeKeys"
-					+ " WHERE transportId = ?"
-					+ " ORDER BY keySetId";
-			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
-			rs = ps.executeQuery();
-			Collection<HandshakeKeySet> keys = new ArrayList<>();
-			for (int i = 0; rs.next(); i++) {
-				// There should be three times as many incoming keys
-				if (inKeys.size() < (i + 1) * 3) throw new DbStateException();
-				HandshakeKeySetId keySetId =
-						new HandshakeKeySetId(rs.getInt(1));
-				ContactId contactId = null;
-				int cId = rs.getInt(2);
-				if (!rs.wasNull()) contactId = new ContactId(cId);
-				PendingContactId pendingContactId = null;
-				byte[] pId = rs.getBytes(3);
-				if (!rs.wasNull()) pendingContactId = new PendingContactId(pId);
-				long timePeriod = rs.getLong(4);
-				SecretKey tagKey = new SecretKey(rs.getBytes(5));
-				SecretKey headerKey = new SecretKey(rs.getBytes(6));
-				SecretKey rootKey = new SecretKey(rs.getBytes(7));
-				boolean alice = rs.getBoolean(8);
-				long streamCounter = rs.getLong(9);
-				OutgoingKeys outCurr = new OutgoingKeys(tagKey, headerKey,
-						timePeriod, streamCounter, true);
-				IncomingKeys inPrev = inKeys.get(i * 3);
-				IncomingKeys inCurr = inKeys.get(i * 3 + 1);
-				IncomingKeys inNext = inKeys.get(i * 3 + 2);
-				HandshakeKeys handshakeKeys = new HandshakeKeys(t, inPrev,
-						inCurr, inNext, outCurr, rootKey, alice);
-				if (contactId == null) {
-					if (pendingContactId == null) throw new DbStateException();
-					keys.add(new HandshakeKeySet(keySetId, pendingContactId,
-							handshakeKeys));
-				} else {
-					if (pendingContactId != null) throw new DbStateException();
-					keys.add(new HandshakeKeySet(keySetId, contactId,
-							handshakeKeys));
-				}
-			}
-			rs.close();
-			ps.close();
-			return keys;
-		} catch (SQLException e) {
-			tryToClose(rs, LOG, WARNING);
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
 	@Override
 	public Identity getIdentity(Connection txn, AuthorId a) throws DbException {
 		PreparedStatement ps = null;
@@ -2522,8 +2328,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs.close();
 			ps.close();
 			// Retrieve the outgoing keys in the same order
-			sql = "SELECT keySetId, contactId, timePeriod,"
-					+ " tagKey, headerKey, stream, active"
+			sql = "SELECT keySetId, timePeriod, contactId, pendingContactId,"
+					+ " tagKey, headerKey, stream, active, rootKey, alice"
 					+ " FROM outgoingKeys"
 					+ " WHERE transportId = ?"
 					+ " ORDER BY keySetId";
@@ -2534,23 +2340,34 @@ abstract class JdbcDatabase implements Database<Connection> {
 			for (int i = 0; rs.next(); i++) {
 				// There should be three times as many incoming keys
 				if (inKeys.size() < (i + 1) * 3) throw new DbStateException();
-				TransportKeySetId keySetId =
-						new TransportKeySetId(rs.getInt(1));
-				ContactId contactId = new ContactId(rs.getInt(2));
-				long timePeriod = rs.getLong(3);
-				SecretKey tagKey = new SecretKey(rs.getBytes(4));
-				SecretKey headerKey = new SecretKey(rs.getBytes(5));
-				long streamCounter = rs.getLong(6);
-				boolean active = rs.getBoolean(7);
+				KeySetId keySetId = new KeySetId(rs.getInt(1));
+				long timePeriod = rs.getLong(2);
+				int cId = rs.getInt(3);
+				ContactId contactId = rs.wasNull() ? null : new ContactId(cId);
+				byte[] pId = rs.getBytes(4);
+				PendingContactId pendingContactId = pId == null ?
+						null : new PendingContactId(pId);
+				SecretKey tagKey = new SecretKey(rs.getBytes(5));
+				SecretKey headerKey = new SecretKey(rs.getBytes(6));
+				long streamCounter = rs.getLong(7);
+				boolean active = rs.getBoolean(8);
+				byte[] rootKey = rs.getBytes(9);
+				boolean alice = rs.getBoolean(10);
 				OutgoingKeys outCurr = new OutgoingKeys(tagKey, headerKey,
 						timePeriod, streamCounter, active);
 				IncomingKeys inPrev = inKeys.get(i * 3);
 				IncomingKeys inCurr = inKeys.get(i * 3 + 1);
 				IncomingKeys inNext = inKeys.get(i * 3 + 2);
-				TransportKeys transportKeys = new TransportKeys(t, inPrev,
-						inCurr, inNext, outCurr);
+				TransportKeys transportKeys;
+				if (rootKey == null) {
+					transportKeys = new TransportKeys(t, inPrev, inCurr,
+							inNext, outCurr);
+				} else {
+					transportKeys = new TransportKeys(t, inPrev, inCurr,
+							inNext, outCurr, new SecretKey(rootKey), alice);
+				}
 				keys.add(new TransportKeySet(keySetId, contactId,
-						transportKeys));
+						pendingContactId, transportKeys));
 			}
 			rs.close();
 			ps.close();
@@ -2564,26 +2381,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public void incrementStreamCounter(Connection txn, TransportId t,
-			HandshakeKeySetId k) throws DbException {
-		PreparedStatement ps = null;
-		try {
-			String sql = "UPDATE outgoingHandshakeKeys SET stream = stream + 1"
-					+ " WHERE transportId = ? AND keySetId = ?";
-			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
-			ps.setInt(2, k.getInt());
-			int affected = ps.executeUpdate();
-			if (affected != 1) throw new DbStateException();
-			ps.close();
-		} catch (SQLException e) {
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
-	@Override
-	public void incrementStreamCounter(Connection txn, TransportId t,
-			TransportKeySetId k) throws DbException {
+			KeySetId k) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET stream = stream + 1"
@@ -2961,27 +2759,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public void removeHandshakeKeys(Connection txn, TransportId t,
-			HandshakeKeySetId k) throws DbException {
-		PreparedStatement ps = null;
-		try {
-			// Delete any existing outgoing keys - this will also remove any
-			// incoming keys with the same key set ID
-			String sql = "DELETE FROM outgoingHandshakeKeys"
-					+ " WHERE transportId = ? AND keySetId = ?";
-			ps = txn.prepareStatement(sql);
-			ps.setString(1, t.getString());
-			ps.setInt(2, k.getInt());
-			int affected = ps.executeUpdate();
-			if (affected < 0) throw new DbStateException();
-			ps.close();
-		} catch (SQLException e) {
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
 	@Override
 	public void removeIdentity(Connection txn, AuthorId a) throws DbException {
 		PreparedStatement ps = null;
@@ -3094,8 +2871,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void removeTransportKeys(Connection txn, TransportId t,
-			TransportKeySetId k) throws DbException {
+	public void removeTransportKeys(Connection txn, TransportId t, KeySetId k)
+			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			// Delete any existing outgoing keys - this will also remove any
@@ -3311,7 +3088,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setInt(1, state.getValue());
 			ps.setBytes(2, p.getBytes());
 			int affected = ps.executeUpdate();
-			if (affected != 1) throw new DbStateException();
+			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps, LOG, WARNING);
@@ -3320,7 +3097,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void setReorderingWindow(Connection txn, TransportKeySetId k,
+	public void setReorderingWindow(Connection txn, KeySetId k,
 			TransportId t, long timePeriod, long base, byte[] bitmap)
 			throws DbException {
 		PreparedStatement ps = null;
@@ -3343,33 +3120,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public void setReorderingWindow(Connection txn, HandshakeKeySetId k,
-			TransportId t, long timePeriod, long base, byte[] bitmap)
-			throws DbException {
-		PreparedStatement ps = null;
-		try {
-			String sql = "UPDATE incomingHandshakeKeys SET base = ?, bitmap = ?"
-					+ " WHERE transportId = ? AND keySetId = ?"
-					+ " AND timePeriod = ?";
-			ps = txn.prepareStatement(sql);
-			ps.setLong(1, base);
-			ps.setBytes(2, bitmap);
-			ps.setString(3, t.getString());
-			ps.setInt(4, k.getInt());
-			ps.setLong(5, timePeriod);
-			int affected = ps.executeUpdate();
-			if (affected < 0 || affected > 1) throw new DbStateException();
-			ps.close();
-		} catch (SQLException e) {
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
 	@Override
 	public void setTransportKeysActive(Connection txn, TransportId t,
-			TransportKeySetId k) throws DbException {
+			KeySetId k) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE outgoingKeys SET active = true"
@@ -3489,71 +3242,4 @@ abstract class JdbcDatabase implements Database<Connection> {
 			throw new DbException(e);
 		}
 	}
-
-	@Override
-	public void updateHandshakeKeys(Connection txn, HandshakeKeySet ks)
-			throws DbException {
-		PreparedStatement ps = null;
-		try {
-			// Update the outgoing keys
-			String sql = "UPDATE outgoingHandshakeKeys SET timePeriod = ?,"
-					+ " tagKey = ?, headerKey = ?, stream = ?"
-					+ " WHERE transportId = ? AND keySetId = ?";
-			ps = txn.prepareStatement(sql);
-			HandshakeKeys k = ks.getKeys();
-			OutgoingKeys outCurr = k.getCurrentOutgoingKeys();
-			ps.setLong(1, outCurr.getTimePeriod());
-			ps.setBytes(2, outCurr.getTagKey().getBytes());
-			ps.setBytes(3, outCurr.getHeaderKey().getBytes());
-			ps.setLong(4, outCurr.getStreamCounter());
-			ps.setString(5, k.getTransportId().getString());
-			ps.setInt(6, ks.getKeySetId().getInt());
-			int affected = ps.executeUpdate();
-			if (affected < 0 || affected > 1) throw new DbStateException();
-			ps.close();
-			// Update the incoming keys
-			sql = "UPDATE incomingHandshakeKeys SET timePeriod = ?,"
-					+ " tagKey = ?, headerKey = ?, base = ?, bitmap = ?"
-					+ " WHERE transportId = ? AND keySetId = ?"
-					+ " AND periodOffset = ?";
-			ps = txn.prepareStatement(sql);
-			ps.setString(6, k.getTransportId().getString());
-			ps.setInt(7, ks.getKeySetId().getInt());
-			// Previous time period
-			IncomingKeys inPrev = k.getPreviousIncomingKeys();
-			ps.setLong(1, inPrev.getTimePeriod());
-			ps.setBytes(2, inPrev.getTagKey().getBytes());
-			ps.setBytes(3, inPrev.getHeaderKey().getBytes());
-			ps.setLong(4, inPrev.getWindowBase());
-			ps.setBytes(5, inPrev.getWindowBitmap());
-			ps.setInt(8, OFFSET_PREV);
-			ps.addBatch();
-			// Current time period
-			IncomingKeys inCurr = k.getCurrentIncomingKeys();
-			ps.setLong(1, inCurr.getTimePeriod());
-			ps.setBytes(2, inCurr.getTagKey().getBytes());
-			ps.setBytes(3, inCurr.getHeaderKey().getBytes());
-			ps.setLong(4, inCurr.getWindowBase());
-			ps.setBytes(5, inCurr.getWindowBitmap());
-			ps.setInt(8, OFFSET_CURR);
-			ps.addBatch();
-			// Next time period
-			IncomingKeys inNext = k.getNextIncomingKeys();
-			ps.setLong(1, inNext.getTimePeriod());
-			ps.setBytes(2, inNext.getTagKey().getBytes());
-			ps.setBytes(3, inNext.getHeaderKey().getBytes());
-			ps.setLong(4, inNext.getWindowBase());
-			ps.setBytes(5, inNext.getWindowBitmap());
-			ps.setInt(8, OFFSET_NEXT);
-			ps.addBatch();
-			int[] batchAffected = ps.executeBatch();
-			if (batchAffected.length != 3) throw new DbStateException();
-			for (int rows : batchAffected)
-				if (rows < 0 || rows > 1) throw new DbStateException();
-			ps.close();
-		} catch (SQLException e) {
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Migration43_44.java

@@ -0,0 +1,58 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration43_44 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration43_44.class.getName());
+
+	private final DatabaseTypes dbTypes;
+
+	Migration43_44(DatabaseTypes dbTypes) {
+		this.dbTypes = dbTypes;
+	}
+
+	@Override
+	public int getStartVersion() {
+		return 43;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 44;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			s.execute("DROP TABLE outgoingHandshakeKeys");
+			s.execute("DROP TABLE incomingHandshakeKeys");
+			s.execute("ALTER TABLE outgoingKeys"
+					+ " ALTER COLUMN contactId DROP NOT NULL");
+			s.execute(dbTypes.replaceTypes("ALTER TABLE outgoingKeys"
+					+ " ADD COLUMN pendingContactId _HASH"));
+			s.execute("ALTER TABLE outgoingKeys"
+					+ " ADD FOREIGN KEY (pendingContactId)"
+					+ " REFERENCES pendingContacts (pendingContactId)"
+					+ " ON DELETE CASCADE");
+			s.execute(dbTypes.replaceTypes("ALTER TABLE outgoingKeys"
+					+ " ADD COLUMN rootKey _SECRET"));
+			s.execute("ALTER TABLE outgoingKeys"
+					+ " ADD COLUMN alice BOOLEAN");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

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

@@ -96,6 +96,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 			TransportConnectionReader r) throws IOException {
 		InputStream streamReader = streamReaderFactory.createStreamReader(
 				r.getInputStream(), ctx);
+		// TODO: Pending contacts, handshake mode
 		return syncSessionFactory.createIncomingSession(ctx.getContactId(),
 				streamReader);
 	}
@@ -104,6 +105,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 			TransportConnectionWriter w) throws IOException {
 		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
 				w.getOutputStream(), ctx);
+		// TODO: Pending contacts, handshake mode
 		return syncSessionFactory.createSimplexOutgoingSession(
 				ctx.getContactId(), w.getMaxLatency(), streamWriter);
 	}
@@ -112,6 +114,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 			TransportConnectionWriter w) throws IOException {
 		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
 				w.getOutputStream(), ctx);
+		// TODO: Pending contacts, handshake mode
 		return syncSessionFactory.createDuplexOutgoingSession(
 				ctx.getContactId(), w.getMaxLatency(), w.getMaxIdleTime(),
 				streamWriter);
@@ -145,6 +148,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 				disposeReader(false, false);
 				return;
 			}
+			// TODO: Pending contacts
 			ContactId contactId = ctx.getContactId();
 			connectionRegistry.registerConnection(contactId, transportId, true);
 			try {
@@ -388,7 +392,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 				return;
 			}
 			// Check that the stream comes from the expected contact
-			if (!ctx.getContactId().equals(contactId)) {
+			if (!contactId.equals(ctx.getContactId())) {
 				LOG.warning("Wrong contact ID for returning stream");
 				disposeReader(true, true);
 				return;

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

@@ -17,8 +17,8 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.transport.KeyManager;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.StreamContext;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -88,10 +88,10 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 	}
 
 	@Override
-	public Map<TransportId, TransportKeySetId> addContact(Transaction txn,
+	public Map<TransportId, KeySetId> addContact(Transaction txn,
 			ContactId c, SecretKey rootKey, long timestamp, boolean alice,
 			boolean active) throws DbException {
-		Map<TransportId, TransportKeySetId> ids = new HashMap<>();
+		Map<TransportId, KeySetId> ids = new HashMap<>();
 		for (Entry<TransportId, TransportKeyManager> e : managers.entrySet()) {
 			TransportId t = e.getKey();
 			TransportKeyManager m = e.getValue();
@@ -101,9 +101,9 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 	}
 
 	@Override
-	public void activateKeys(Transaction txn, Map<TransportId,
-			TransportKeySetId> keys) throws DbException {
-		for (Entry<TransportId, TransportKeySetId> e : keys.entrySet()) {
+	public void activateKeys(Transaction txn, Map<TransportId, KeySetId> keys)
+			throws DbException {
+		for (Entry<TransportId, KeySetId> e : keys.entrySet()) {
 			TransportId t = e.getKey();
 			TransportKeyManager m = managers.get(t);
 			if (m == null) {

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

@@ -1,30 +0,0 @@
-package org.briarproject.bramble.transport;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
-
-class MutableKeySet {
-
-	private final TransportKeySetId keySetId;
-	private final ContactId contactId;
-	private final MutableTransportKeys transportKeys;
-
-	MutableKeySet(TransportKeySetId keySetId, ContactId contactId,
-			MutableTransportKeys transportKeys) {
-		this.keySetId = keySetId;
-		this.contactId = contactId;
-		this.transportKeys = transportKeys;
-	}
-
-	TransportKeySetId getKeySetId() {
-		return keySetId;
-	}
-
-	ContactId getContactId() {
-		return contactId;
-	}
-
-	MutableTransportKeys getTransportKeys() {
-		return transportKeys;
-	}
-}

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

@@ -0,0 +1,50 @@
+package org.briarproject.bramble.transport;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.transport.KeySetId;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.NotThreadSafe;
+
+@NotThreadSafe
+@NotNullByDefault
+class MutableTransportKeySet {
+
+	private final KeySetId keySetId;
+	@Nullable
+	private final ContactId contactId;
+	@Nullable
+	private final PendingContactId pendingContactId;
+	private final MutableTransportKeys keys;
+
+	MutableTransportKeySet(KeySetId keySetId, @Nullable ContactId contactId,
+			@Nullable PendingContactId pendingContactId,
+			MutableTransportKeys keys) {
+		if ((contactId == null) == (pendingContactId == null))
+			throw new IllegalArgumentException();
+		this.keySetId = keySetId;
+		this.contactId = contactId;
+		this.pendingContactId = pendingContactId;
+		this.keys = keys;
+	}
+
+	KeySetId getKeySetId() {
+		return keySetId;
+	}
+
+	@Nullable
+	ContactId getContactId() {
+		return contactId;
+	}
+
+	@Nullable
+	PendingContactId getPendingContactId() {
+		return pendingContactId;
+	}
+
+	MutableTransportKeys getKeys() {
+		return keys;
+	}
+}

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

@@ -1,9 +1,11 @@
 package org.briarproject.bramble.transport;
 
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
 @NotThreadSafe
@@ -13,6 +15,9 @@ class MutableTransportKeys {
 	private final TransportId transportId;
 	private final MutableIncomingKeys inPrev, inCurr, inNext;
 	private final MutableOutgoingKeys outCurr;
+	@Nullable
+	private final SecretKey rootKey;
+	private final boolean alice;
 
 	MutableTransportKeys(TransportKeys k) {
 		transportId = k.getTransportId();
@@ -20,11 +25,24 @@ class MutableTransportKeys {
 		inCurr = new MutableIncomingKeys(k.getCurrentIncomingKeys());
 		inNext = new MutableIncomingKeys(k.getNextIncomingKeys());
 		outCurr = new MutableOutgoingKeys(k.getCurrentOutgoingKeys());
+		if (k.isHandshakeMode()) {
+			rootKey = k.getRootKey();
+			alice = k.isAlice();
+		} else {
+			rootKey = null;
+			alice = false;
+		}
 	}
 
 	TransportKeys snapshot() {
-		return new TransportKeys(transportId, inPrev.snapshot(),
-				inCurr.snapshot(), inNext.snapshot(), outCurr.snapshot());
+		if (rootKey == null) {
+			return new TransportKeys(transportId, inPrev.snapshot(),
+					inCurr.snapshot(), inNext.snapshot(), outCurr.snapshot());
+		} else {
+			return new TransportKeys(transportId, inPrev.snapshot(),
+					inCurr.snapshot(), inNext.snapshot(), outCurr.snapshot(),
+					rootKey, alice);
+		}
 	}
 
 	TransportId getTransportId() {
@@ -46,4 +64,18 @@ class MutableTransportKeys {
 	MutableOutgoingKeys getCurrentOutgoingKeys() {
 		return outCurr;
 	}
+
+	boolean isHandshakeMode() {
+		return rootKey != null;
+	}
+
+	SecretKey getRootKey() {
+		if (rootKey == null) throw new UnsupportedOperationException();
+		return rootKey;
+	}
+
+	boolean isAlice() {
+		if (rootKey == null) throw new UnsupportedOperationException();
+		return alice;
+	}
 }

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

@@ -5,8 +5,8 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.StreamContext;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 
 import javax.annotation.Nullable;
 
@@ -15,11 +15,10 @@ interface TransportKeyManager {
 
 	void start(Transaction txn) throws DbException;
 
-	TransportKeySetId addContact(Transaction txn, ContactId c,
-			SecretKey rootKey, long timestamp, boolean alice, boolean active)
-			throws DbException;
+	KeySetId addContact(Transaction txn, ContactId c, SecretKey rootKey,
+			long timestamp, boolean alice, boolean active) throws DbException;
 
-	void activateKeys(Transaction txn, TransportKeySetId k) throws DbException;
+	void activateKeys(Transaction txn, KeySetId k) throws DbException;
 
 	void removeContact(ContactId c);
 

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.transport;
 
 import org.briarproject.bramble.api.Bytes;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.TransportCrypto;
 import org.briarproject.bramble.api.db.DatabaseComponent;
@@ -11,9 +12,9 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.Scheduler;
+import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.StreamContext;
 import org.briarproject.bramble.api.transport.TransportKeySet;
-import org.briarproject.bramble.api.transport.TransportKeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import org.briarproject.bramble.transport.ReorderingWindow.Change;
 
@@ -28,10 +29,13 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.transport.TransportConstants.MAX_CLOCK_DIFFERENCE;
 import static org.briarproject.bramble.api.transport.TransportConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENGTH;
@@ -43,7 +47,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class TransportKeyManagerImpl implements TransportKeyManager {
 
 	private static final Logger LOG =
-			Logger.getLogger(TransportKeyManagerImpl.class.getName());
+			getLogger(TransportKeyManagerImpl.class.getName());
 
 	private final DatabaseComponent db;
 	private final TransportCrypto transportCrypto;
@@ -55,10 +59,13 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	private final AtomicBoolean used = new AtomicBoolean(false);
 	private final ReentrantLock lock = new ReentrantLock();
 
-	// The following are locking: lock
-	private final Map<TransportKeySetId, MutableKeySet> keys = new HashMap<>();
+	@GuardedBy("lock")
+	private final Map<KeySetId, MutableTransportKeySet> keys = new HashMap<>();
+	@GuardedBy("lock")
 	private final Map<Bytes, TagContext> inContexts = new HashMap<>();
-	private final Map<ContactId, MutableKeySet> outContexts = new HashMap<>();
+	@GuardedBy("lock")
+	private final Map<ContactId, MutableTransportKeySet> outContexts =
+			new HashMap<>();
 
 	TransportKeyManagerImpl(DatabaseComponent db,
 			TransportCrypto transportCrypto, Executor dbExecutor,
@@ -82,62 +89,70 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			// Load the transport keys from the DB
 			Collection<TransportKeySet> loaded =
 					db.getTransportKeys(txn, transportId);
-			// Rotate the keys to the current time period
-			RotationResult rotationResult = rotateKeys(loaded, now);
+			// Update the keys to the current time period
+			UpdateResult updateResult = updateKeys(loaded, now);
 			// Initialise mutable state for all contacts
-			addKeys(rotationResult.current);
-			// Write any rotated keys back to the DB
-			if (!rotationResult.rotated.isEmpty())
-				db.updateTransportKeys(txn, rotationResult.rotated);
+			addKeys(updateResult.current);
+			// Write any updated keys back to the DB
+			if (!updateResult.updated.isEmpty())
+				db.updateTransportKeys(txn, updateResult.updated);
 		} finally {
 			lock.unlock();
 		}
-		// Schedule the next key rotation
-		scheduleKeyRotation(now);
+		// Schedule the next key update
+		scheduleKeyUpdate(now);
 	}
 
-	private RotationResult rotateKeys(Collection<TransportKeySet> keys,
+	private UpdateResult updateKeys(Collection<TransportKeySet> keys,
 			long now) {
-		RotationResult rotationResult = new RotationResult();
+		UpdateResult updateResult = new UpdateResult();
 		long timePeriod = now / timePeriodLength;
 		for (TransportKeySet ks : keys) {
 			TransportKeys k = ks.getKeys();
-			TransportKeys k1 = transportCrypto.rotateTransportKeys(k,
+			TransportKeys k1 = transportCrypto.updateTransportKeys(k,
 					timePeriod);
 			TransportKeySet ks1 = new TransportKeySet(ks.getKeySetId(),
-					ks.getContactId(), k1);
+					ks.getContactId(), null, k1);
 			if (k1.getTimePeriod() > k.getTimePeriod())
-				rotationResult.rotated.add(ks1);
-			rotationResult.current.add(ks1);
+				updateResult.updated.add(ks1);
+			updateResult.current.add(ks1);
 		}
-		return rotationResult;
+		return updateResult;
 	}
 
-	// Locking: lock
+	@GuardedBy("lock")
 	private void addKeys(Collection<TransportKeySet> keys) {
 		for (TransportKeySet ks : keys) {
 			addKeys(ks.getKeySetId(), ks.getContactId(),
+					ks.getPendingContactId(),
 					new MutableTransportKeys(ks.getKeys()));
 		}
 	}
 
-	// Locking: lock
-	private void addKeys(TransportKeySetId keySetId, ContactId contactId,
-			MutableTransportKeys m) {
-		MutableKeySet ks = new MutableKeySet(keySetId, contactId, m);
-		keys.put(keySetId, ks);
-		encodeTags(keySetId, contactId, m.getPreviousIncomingKeys());
-		encodeTags(keySetId, contactId, m.getCurrentIncomingKeys());
-		encodeTags(keySetId, contactId, m.getNextIncomingKeys());
+	@GuardedBy("lock")
+	private void addKeys(KeySetId keySetId, @Nullable ContactId contactId,
+			@Nullable PendingContactId pendingContactId,
+			MutableTransportKeys keys) {
+		MutableTransportKeySet ks = new MutableTransportKeySet(keySetId,
+				contactId, pendingContactId, keys);
+		this.keys.put(keySetId, ks);
+		boolean handshakeMode = keys.isHandshakeMode();
+		encodeTags(keySetId, contactId, pendingContactId,
+				keys.getPreviousIncomingKeys(), handshakeMode);
+		encodeTags(keySetId, contactId, pendingContactId,
+				keys.getCurrentIncomingKeys(), handshakeMode);
+		encodeTags(keySetId, contactId, pendingContactId,
+				keys.getNextIncomingKeys(), handshakeMode);
 		considerReplacingOutgoingKeys(ks);
 	}
 
-	// Locking: lock
-	private void encodeTags(TransportKeySetId keySetId, ContactId contactId,
-			MutableIncomingKeys inKeys) {
+	@GuardedBy("lock")
+	private void encodeTags(KeySetId keySetId, @Nullable ContactId contactId,
+			@Nullable PendingContactId pendingContactId,
+			MutableIncomingKeys inKeys, boolean handshakeMode) {
 		for (long streamNumber : inKeys.getWindow().getUnseen()) {
-			TagContext tagCtx =
-					new TagContext(keySetId, contactId, inKeys, streamNumber);
+			TagContext tagCtx = new TagContext(keySetId, contactId,
+					pendingContactId, inKeys, streamNumber, handshakeMode);
 			byte[] tag = new byte[TAG_LENGTH];
 			transportCrypto.encodeTag(tag, inKeys.getTagKey(), PROTOCOL_VERSION,
 					streamNumber);
@@ -145,27 +160,30 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		}
 	}
 
-	// Locking: lock
-	private void considerReplacingOutgoingKeys(MutableKeySet ks) {
+	@GuardedBy("lock")
+	private void considerReplacingOutgoingKeys(MutableTransportKeySet ks) {
 		// Use the active outgoing keys with the highest key set ID
-		if (ks.getTransportKeys().getCurrentOutgoingKeys().isActive()) {
-			MutableKeySet old = outContexts.get(ks.getContactId());
+		ContactId c = ks.getContactId();
+		if (c != null && ks.getKeys().getCurrentOutgoingKeys().isActive()) {
+			MutableTransportKeySet old = outContexts.get(c);
 			if (old == null ||
+					(old.getKeys().isHandshakeMode() &&
+							!ks.getKeys().isHandshakeMode()) ||
 					old.getKeySetId().getInt() < ks.getKeySetId().getInt()) {
-				outContexts.put(ks.getContactId(), ks);
+				outContexts.put(c, ks);
 			}
 		}
 	}
 
-	private void scheduleKeyRotation(long now) {
+	private void scheduleKeyUpdate(long now) {
 		long delay = timePeriodLength - now % timePeriodLength;
-		scheduler.schedule((Runnable) this::rotateKeys, delay, MILLISECONDS);
+		scheduler.schedule((Runnable) this::updateKeys, delay, MILLISECONDS);
 	}
 
-	private void rotateKeys() {
+	private void updateKeys() {
 		dbExecutor.execute(() -> {
 			try {
-				db.transaction(false, this::rotateKeys);
+				db.transaction(false, this::updateKeys);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -173,23 +191,22 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	}
 
 	@Override
-	public TransportKeySetId addContact(Transaction txn, ContactId c,
-			SecretKey rootKey, long timestamp, boolean alice, boolean active)
-			throws DbException {
+	public KeySetId addContact(Transaction txn, ContactId c, SecretKey rootKey,
+			long timestamp, boolean alice, boolean active) throws DbException {
 		lock.lock();
 		try {
 			// Work out what time period the timestamp belongs to
 			long timePeriod = timestamp / timePeriodLength;
 			// Derive the transport keys
-			TransportKeys k = transportCrypto.deriveTransportKeys(transportId,
+			TransportKeys k = transportCrypto.deriveRotationKeys(transportId,
 					rootKey, timePeriod, alice, active);
-			// Rotate the keys to the current time period if necessary
+			// Update the keys to the current time period if necessary
 			timePeriod = clock.currentTimeMillis() / timePeriodLength;
-			k = transportCrypto.rotateTransportKeys(k, timePeriod);
+			k = transportCrypto.updateTransportKeys(k, timePeriod);
 			// Write the keys back to the DB
-			TransportKeySetId keySetId = db.addTransportKeys(txn, c, k);
+			KeySetId keySetId = db.addTransportKeys(txn, c, k);
 			// Initialise mutable state for the contact
-			addKeys(keySetId, c, new MutableTransportKeys(k));
+			addKeys(keySetId, c, null, new MutableTransportKeys(k));
 			return keySetId;
 		} finally {
 			lock.unlock();
@@ -197,13 +214,12 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	}
 
 	@Override
-	public void activateKeys(Transaction txn, TransportKeySetId k)
-			throws DbException {
+	public void activateKeys(Transaction txn, KeySetId k) throws DbException {
 		lock.lock();
 		try {
-			MutableKeySet ks = keys.get(k);
+			MutableTransportKeySet ks = keys.get(k);
 			if (ks == null) throw new IllegalArgumentException();
-			MutableTransportKeys m = ks.getTransportKeys();
+			MutableTransportKeys m = ks.getKeys();
 			m.getCurrentOutgoingKeys().activate();
 			considerReplacingOutgoingKeys(ks);
 			db.setTransportKeysActive(txn, m.getTransportId(), k);
@@ -218,13 +234,11 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		try {
 			// Remove mutable state for the contact
 			Iterator<TagContext> it = inContexts.values().iterator();
-			while (it.hasNext()) if (it.next().contactId.equals(c)) it.remove();
+			while (it.hasNext()) if (c.equals(it.next().contactId)) it.remove();
 			outContexts.remove(c);
-			Iterator<MutableKeySet> it1 = keys.values().iterator();
-			while (it1.hasNext()) {
-				ContactId c1 = it1.next().getContactId();
-				if (c1 != null && c1.equals(c)) it1.remove();
-			}
+			Iterator<MutableTransportKeySet> it1 = keys.values().iterator();
+			while (it1.hasNext())
+				if (c.equals(it1.next().getContactId())) it1.remove();
 		} finally {
 			lock.unlock();
 		}
@@ -234,10 +248,10 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	public boolean canSendOutgoingStreams(ContactId c) {
 		lock.lock();
 		try {
-			MutableKeySet ks = outContexts.get(c);
+			MutableTransportKeySet ks = outContexts.get(c);
 			if (ks == null) return false;
 			MutableOutgoingKeys outKeys =
-					ks.getTransportKeys().getCurrentOutgoingKeys();
+					ks.getKeys().getCurrentOutgoingKeys();
 			if (!outKeys.isActive()) throw new AssertionError();
 			return outKeys.getStreamCounter() <= MAX_32_BIT_UNSIGNED;
 		} finally {
@@ -251,16 +265,16 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		lock.lock();
 		try {
 			// Look up the outgoing keys for the contact
-			MutableKeySet ks = outContexts.get(c);
+			MutableTransportKeySet ks = outContexts.get(c);
 			if (ks == null) return null;
-			MutableOutgoingKeys outKeys =
-					ks.getTransportKeys().getCurrentOutgoingKeys();
+			MutableTransportKeys keys = ks.getKeys();
+			MutableOutgoingKeys outKeys = keys.getCurrentOutgoingKeys();
 			if (!outKeys.isActive()) throw new AssertionError();
 			if (outKeys.getStreamCounter() > MAX_32_BIT_UNSIGNED) return null;
 			// Create a stream context
-			StreamContext ctx = new StreamContext(c, transportId,
+			StreamContext ctx = new StreamContext(c, null, transportId,
 					outKeys.getTagKey(), outKeys.getHeaderKey(),
-					outKeys.getStreamCounter());
+					outKeys.getStreamCounter(), keys.isHandshakeMode());
 			// Increment the stream counter and write it back to the DB
 			outKeys.incrementStreamCounter();
 			db.incrementStreamCounter(txn, transportId, ks.getKeySetId());
@@ -280,9 +294,10 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 			if (tagCtx == null) return null;
 			MutableIncomingKeys inKeys = tagCtx.inKeys;
 			// Create a stream context
-			StreamContext ctx = new StreamContext(tagCtx.contactId, transportId,
+			StreamContext ctx = new StreamContext(tagCtx.contactId,
+					tagCtx.pendingContactId, transportId,
 					inKeys.getTagKey(), inKeys.getHeaderKey(),
-					tagCtx.streamNumber);
+					tagCtx.streamNumber, tagCtx.handshakeMode);
 			// Update the reordering window
 			ReorderingWindow window = inKeys.getWindow();
 			Change change = window.setSeen(tagCtx.streamNumber);
@@ -292,7 +307,8 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 				transportCrypto.encodeTag(addTag, inKeys.getTagKey(),
 						PROTOCOL_VERSION, streamNumber);
 				TagContext tagCtx1 = new TagContext(tagCtx.keySetId,
-						tagCtx.contactId, inKeys, streamNumber);
+						tagCtx.contactId, tagCtx.pendingContactId, inKeys,
+						streamNumber, tagCtx.handshakeMode);
 				inContexts.put(new Bytes(addTag), tagCtx1);
 			}
 			// Remove tags for any stream numbers removed from the window
@@ -308,9 +324,9 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 					inKeys.getTimePeriod(), window.getBase(),
 					window.getBitmap());
 			// If the outgoing keys are inactive, activate them
-			MutableKeySet ks = keys.get(tagCtx.keySetId);
+			MutableTransportKeySet ks = keys.get(tagCtx.keySetId);
 			MutableOutgoingKeys outKeys =
-					ks.getTransportKeys().getCurrentOutgoingKeys();
+					ks.getKeys().getCurrentOutgoingKeys();
 			if (!outKeys.isActive()) {
 				LOG.info("Activating outgoing keys");
 				outKeys.activate();
@@ -323,51 +339,60 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 		}
 	}
 
-	private void rotateKeys(Transaction txn) throws DbException {
+	private void updateKeys(Transaction txn) throws DbException {
 		long now = clock.currentTimeMillis();
 		lock.lock();
 		try {
-			// Rotate the keys to the current time period
+			// Update the keys to the current time period
 			Collection<TransportKeySet> snapshot = new ArrayList<>(keys.size());
-			for (MutableKeySet ks : keys.values()) {
+			for (MutableTransportKeySet ks : keys.values()) {
 				snapshot.add(new TransportKeySet(ks.getKeySetId(),
-						ks.getContactId(), ks.getTransportKeys().snapshot()));
+						ks.getContactId(), ks.getPendingContactId(),
+						ks.getKeys().snapshot()));
 			}
-			RotationResult rotationResult = rotateKeys(snapshot, now);
+			UpdateResult updateResult = updateKeys(snapshot, now);
 			// Rebuild the mutable state for all contacts
 			inContexts.clear();
 			outContexts.clear();
 			keys.clear();
-			addKeys(rotationResult.current);
-			// Write any rotated keys back to the DB
-			if (!rotationResult.rotated.isEmpty())
-				db.updateTransportKeys(txn, rotationResult.rotated);
+			addKeys(updateResult.current);
+			// Write any updated keys back to the DB
+			if (!updateResult.updated.isEmpty())
+				db.updateTransportKeys(txn, updateResult.updated);
 		} finally {
 			lock.unlock();
 		}
-		// Schedule the next key rotation
-		scheduleKeyRotation(now);
+		// Schedule the next key update
+		scheduleKeyUpdate(now);
 	}
 
 	private static class TagContext {
 
-		private final TransportKeySetId keySetId;
+		private final KeySetId keySetId;
+		@Nullable
 		private final ContactId contactId;
+		@Nullable
+		private final PendingContactId pendingContactId;
 		private final MutableIncomingKeys inKeys;
 		private final long streamNumber;
+		private final boolean handshakeMode;
 
-		private TagContext(TransportKeySetId keySetId, ContactId contactId,
-				MutableIncomingKeys inKeys, long streamNumber) {
+		private TagContext(KeySetId keySetId, @Nullable ContactId contactId,
+				@Nullable PendingContactId pendingContactId,
+				MutableIncomingKeys inKeys, long streamNumber,
+				boolean handshakeMode) {
 			this.keySetId = keySetId;
 			this.contactId = contactId;
+			this.pendingContactId = pendingContactId;
 			this.inKeys = inKeys;
 			this.streamNumber = streamNumber;
+			this.handshakeMode = handshakeMode;
 		}
 	}
 
-	private static class RotationResult {
+	private static class UpdateResult {
 
 		private final Collection<TransportKeySet> current = new ArrayList<>();
-		private final Collection<TransportKeySet> rotated = new ArrayList<>();
+		private final Collection<TransportKeySet> updated = new ArrayList<>();
 	}
 }