Merge branch 'static-transport-keys' into 'master'

Add database support for pending contacts and handshake keys

See merge request !1078

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

@@ -18,30 +18,30 @@ public interface ContactExchangeTask {
 	byte PROTOCOL_VERSION = 1;
 
 	/**
-	 * Label for deriving Alice's header key from the master secret.
+	 * Label for deriving Alice's header key from the master key.
 	 */
 	String ALICE_KEY_LABEL =
 			"org.briarproject.bramble.contact/ALICE_HEADER_KEY";
 
 	/**
-	 * Label for deriving Bob's header key from the master secret.
+	 * Label for deriving Bob's header key from the master key.
 	 */
 	String BOB_KEY_LABEL = "org.briarproject.bramble.contact/BOB_HEADER_KEY";
 
 	/**
-	 * Label for deriving Alice's key binding nonce from the master secret.
+	 * Label for deriving Alice's key binding nonce from the master key.
 	 */
 	String ALICE_NONCE_LABEL = "org.briarproject.bramble.contact/ALICE_NONCE";
 
 	/**
-	 * Label for deriving Bob's key binding nonce from the master secret.
+	 * Label for deriving Bob's key binding nonce from the master key.
 	 */
 	String BOB_NONCE_LABEL = "org.briarproject.bramble.contact/BOB_NONCE";
 
 	/**
 	 * Exchanges contact information with a remote peer.
 	 */
-	void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
+	void startExchange(LocalAuthor localAuthor, SecretKey masterKey,
 			DuplexTransportConnection conn, TransportId transportId,
 			boolean alice);
 }

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

@@ -13,8 +13,6 @@ import java.util.Collection;
 
 import javax.annotation.Nullable;
 
-import static org.briarproject.bramble.api.contact.PendingContact.PendingContactState.FAILED;
-
 @NotNullByDefault
 public interface ContactManager {
 
@@ -33,7 +31,7 @@ public interface ContactManager {
 	 * @param alice true if the local party is Alice
 	 */
 	ContactId addContact(Transaction txn, Author remote, AuthorId local,
-			SecretKey master, long timestamp, boolean alice, boolean verified,
+			SecretKey rootKey, long timestamp, boolean alice, boolean verified,
 			boolean active) throws DbException;
 
 	/**
@@ -50,7 +48,7 @@ public interface ContactManager {
 	 *
 	 * @param alice true if the local party is Alice
 	 */
-	ContactId addContact(Author remote, AuthorId local, SecretKey master,
+	ContactId addContact(Author remote, AuthorId local, SecretKey rootKey,
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException;
 
@@ -79,7 +77,8 @@ public interface ContactManager {
 	Collection<PendingContact> getPendingContacts();
 
 	/**
-	 * Removes a {@link PendingContact} that is in state {@link FAILED}.
+	 * Removes a {@link PendingContact} that is in state
+	 * {@link PendingContactState FAILED}.
 	 */
 	void removePendingContact(PendingContact pendingContact);
 

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

@@ -8,26 +8,29 @@ import javax.annotation.concurrent.Immutable;
 @NotNullByDefault
 public class PendingContact {
 
-	public enum PendingContactState {
-		WAITING_FOR_CONNECTION,
-		CONNECTED,
-		ADDING_CONTACT,
-		FAILED
-	}
-
 	private final PendingContactId id;
+	private final byte[] publicKey;
 	private final String alias;
 	private final PendingContactState state;
 	private final long timestamp;
 
-	public PendingContact(PendingContactId id, String alias,
-			PendingContactState state, long timestamp) {
+	public PendingContact(PendingContactId id, byte[] publicKey,
+			String alias, PendingContactState state, long timestamp) {
 		this.id = id;
+		this.publicKey = publicKey;
 		this.alias = alias;
 		this.state = state;
 		this.timestamp = timestamp;
 	}
 
+	public PendingContactId getId() {
+		return id;
+	}
+
+	public byte[] getPublicKey() {
+		return publicKey;
+	}
+
 	public String getAlias() {
 		return alias;
 	}
@@ -50,5 +53,4 @@ public class PendingContact {
 		return o instanceof PendingContact &&
 				id.equals(((PendingContact) o).id);
 	}
-
 }

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

+package org.briarproject.bramble.api.contact;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public enum PendingContactState {
+
+	WAITING_FOR_CONNECTION(0),
+	CONNECTED(1),
+	ADDING_CONTACT(2),
+	FAILED(3);
+
+	private final int value;
+
+	PendingContactState(int value) {
+		this.value = value;
+	}
+
+	public int getValue() {
+		return value;
+	}
+
+	public static PendingContactState fromValue(int value) {
+		for (PendingContactState s : values()) if (s.value == value) return s;
+		throw new IllegalArgumentException();
+	}
+}

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

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

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

 package org.briarproject.bramble.api.crypto;
 
 import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.transport.HandshakeKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 /**
@@ -11,19 +12,34 @@ public interface TransportCrypto {
 
 	/**
 	 * Derives initial transport keys for the given transport in the given
-	 * rotation period from the given master secret.
+	 * time period from the given root key.
 	 *
 	 * @param alice whether the keys are for use by Alice or Bob.
 	 * @param active whether the keys are usable for outgoing streams.
 	 */
-	TransportKeys deriveTransportKeys(TransportId t, SecretKey master,
-			long rotationPeriod, boolean alice, boolean active);
+	TransportKeys deriveTransportKeys(TransportId t, SecretKey rootKey,
+			long timePeriod, boolean alice, boolean active);
 
 	/**
-	 * Rotates the given transport keys to the given rotation period. If the
-	 * keys are for the given period or any later period they are not rotated.
+	 * Rotates the given transport keys to the given time period. If the keys
+	 * are for the given period or any later period they are not rotated.
 	 */
-	TransportKeys rotateTransportKeys(TransportKeys k, long rotationPeriod);
+	TransportKeys rotateTransportKeys(TransportKeys k, long timePeriod);
+
+	/**
+	 * Derives handshake keys for the given transport in the given time period
+	 * from the given root key.
+	 *
+	 * @param alice whether the keys are for use by Alice or Bob.
+	 */
+	HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
+			long timePeriod, boolean alice);
+
+	/**
+	 * Updates the given handshake keys to the given time period. If the keys
+	 * are for the given period or any later period they are not updated.
+	 */
+	HandshakeKeys updateHandshakeKeys(HandshakeKeys k, long timePeriod);
 
 	/**
 	 * Encodes the pseudo-random tag that is used to recognise a stream.

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

@@ -2,6 +2,8 @@ package org.briarproject.bramble.api.db;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContact;
+import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
@@ -20,8 +22,11 @@ import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.validation.MessageState;
-import org.briarproject.bramble.api.transport.KeySet;
-import org.briarproject.bramble.api.transport.KeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeySet;
+import org.briarproject.bramble.api.transport.HandshakeKeySetId;
+import org.briarproject.bramble.api.transport.HandshakeKeys;
+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;
@@ -108,6 +113,20 @@ public interface DatabaseComponent {
 	 */
 	void addGroup(Transaction txn, Group g) throws DbException;
 
+	/**
+	 * Stores the given handshake keys for the given contact and returns a
+	 * key set ID.
+	 */
+	HandshakeKeySetId addHandshakeKeys(Transaction 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(Transaction txn, PendingContactId p,
+			HandshakeKeys k) throws DbException;
+
 	/**
 	 * Stores a local pseudonym.
 	 */
@@ -119,6 +138,12 @@ public interface DatabaseComponent {
 	void addLocalMessage(Transaction txn, Message m, Metadata meta,
 			boolean shared) throws DbException;
 
+	/**
+	 * Stores a pending contact.
+	 */
+	void addPendingContact(Transaction txn, PendingContact p)
+			throws DbException;
+
 	/**
 	 * Stores a transport.
 	 */
@@ -129,27 +154,41 @@ public interface DatabaseComponent {
 	 * Stores the given transport keys for the given contact and returns a
 	 * key set ID.
 	 */
-	KeySetId addTransportKeys(Transaction txn, ContactId c,
+	TransportKeySetId addTransportKeys(Transaction txn, ContactId c,
 			TransportKeys k) throws DbException;
 
 	/**
 	 * Returns true if the database contains the given contact for the given
 	 * local pseudonym.
+	 * <p/>
+	 * Read-only.
 	 */
 	boolean containsContact(Transaction txn, AuthorId remote, AuthorId local)
 			throws DbException;
 
 	/**
 	 * Returns true if the database contains the given group.
+	 * <p/>
+	 * Read-only.
 	 */
 	boolean containsGroup(Transaction txn, GroupId g) throws DbException;
 
 	/**
 	 * Returns true if the database contains the given local author.
+	 * <p/>
+	 * Read-only.
 	 */
 	boolean containsLocalAuthor(Transaction txn, AuthorId local)
 			throws DbException;
 
+	/**
+	 * Returns true if the database contains the given pending contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	boolean containsPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Deletes the message with the given ID. Unlike
 	 * {@link #removeMessage(Transaction, MessageId)}, the message ID,
@@ -269,6 +308,14 @@ public interface DatabaseComponent {
 	Visibility getGroupVisibility(Transaction txn, ContactId c, GroupId g)
 			throws DbException;
 
+	/**
+	 * Returns all handshake keys for the given transport.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<HandshakeKeySet> getHandshakeKeys(Transaction txn, TransportId t)
+			throws DbException;
+
 	/**
 	 * Returns the local pseudonym with the given ID.
 	 * <p/>
@@ -417,6 +464,14 @@ public interface DatabaseComponent {
 	 */
 	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns all pending contacts.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<PendingContact> getPendingContacts(Transaction txn)
+			throws DbException;
+
 	/**
 	 * Returns all settings in the given namespace.
 	 * <p/>
@@ -429,14 +484,20 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<KeySet> getTransportKeys(Transaction txn, TransportId t)
+	Collection<TransportKeySet> getTransportKeys(Transaction txn, TransportId t)
 			throws DbException;
 
+	/**
+	 * Increments the outgoing stream counter for the given handshake keys.
+	 */
+	void incrementStreamCounter(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
-	void incrementStreamCounter(Transaction txn, TransportId t, KeySetId k)
-			throws DbException;
+	void incrementStreamCounter(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Merges the given metadata with the existing metadata for the given
@@ -491,6 +552,12 @@ public interface DatabaseComponent {
 	 */
 	void removeGroup(Transaction txn, Group g) throws DbException;
 
+	/**
+	 * Removes the given handshake keys from the database.
+	 */
+	void removeHandshakeKeys(Transaction txn, TransportId t,
+			HandshakeKeySetId k) throws DbException;
+
 	/**
 	 * Removes a local pseudonym (and all associated state) from the database.
 	 */
@@ -501,6 +568,12 @@ public interface DatabaseComponent {
 	 */
 	void removeMessage(Transaction txn, MessageId m) throws DbException;
 
+	/**
+	 * Removes a pending contact (and all associated state) from the database.
+	 */
+	void removePendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */
@@ -509,8 +582,8 @@ public interface DatabaseComponent {
 	/**
 	 * Removes the given transport keys from the database.
 	 */
-	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
-			throws DbException;
+	void removeTransportKeys(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
 
 	/**
 	 * Marks the given contact as verified.
@@ -553,21 +626,36 @@ public interface DatabaseComponent {
 			Collection<MessageId> dependencies) throws DbException;
 
 	/**
-	 * Sets the reordering window for the given key set and transport in the
-	 * given rotation period.
+	 * Sets the reordering window for the given transport key set in the given
+	 * time period.
 	 */
-	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
-			long rotationPeriod, long base, byte[] bitmap) throws DbException;
+	void setReorderingWindow(Transaction 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(Transaction txn, HandshakeKeySetId k,
+			TransportId t, long timePeriod, long base, byte[] bitmap)
+			throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
-	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
+	void setTransportKeysActive(Transaction txn, TransportId t,
+			TransportKeySetId k) throws DbException;
+
+	/**
+	 * Stores the given handshake keys, deleting any keys they have replaced.
+	 */
+	void updateHandshakeKeys(Transaction txn, Collection<HandshakeKeySet> keys)
 			throws DbException;
 
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */
-	void updateTransportKeys(Transaction txn, Collection<KeySet> keys)
+	void updateTransportKeys(Transaction txn, Collection<TransportKeySet> keys)
 			throws DbException;
 }

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

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

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

+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when a duplicate pending contact is added to the database. This
+ * exception may occur due to concurrent updates and does not indicate a
+ * database error.
+ */
+public class PendingContactExistsException extends DbException {
+}

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

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

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

+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Abstract superclass for {@link TransportKeys} and {@link HandshakeKeys}.
+ */
+@Immutable
+@NotNullByDefault
+public abstract class AbstractTransportKeys {
+
+	private final TransportId transportId;
+	private final IncomingKeys inPrev, inCurr, inNext;
+	private final OutgoingKeys outCurr;
+
+	AbstractTransportKeys(TransportId transportId, IncomingKeys inPrev,
+			IncomingKeys inCurr, IncomingKeys inNext, OutgoingKeys outCurr) {
+		if (inPrev.getTimePeriod() != outCurr.getTimePeriod() - 1)
+			throw new IllegalArgumentException();
+		if (inCurr.getTimePeriod() != outCurr.getTimePeriod())
+			throw new IllegalArgumentException();
+		if (inNext.getTimePeriod() != outCurr.getTimePeriod() + 1)
+			throw new IllegalArgumentException();
+		this.transportId = transportId;
+		this.inPrev = inPrev;
+		this.inCurr = inCurr;
+		this.inNext = inNext;
+		this.outCurr = outCurr;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public IncomingKeys getPreviousIncomingKeys() {
+		return inPrev;
+	}
+
+	public IncomingKeys getCurrentIncomingKeys() {
+		return inCurr;
+	}
+
+	public IncomingKeys getNextIncomingKeys() {
+		return inNext;
+	}
+
+	public OutgoingKeys getCurrentOutgoingKeys() {
+		return outCurr;
+	}
+
+	public long getTimePeriod() {
+		return outCurr.getTimePeriod();
+	}
+}

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

+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A set of keys for handshaking with a given contact or pending contact over a
+ * given transport. Unlike a {@link TransportKeySet} these keys do not provide
+ * forward secrecy.
+ */
+@Immutable
+@NotNullByDefault
+public class HandshakeKeySet {
+
+	private final HandshakeKeySetId keySetId;
+	@Nullable
+	private final ContactId contactId;
+	@Nullable
+	private final PendingContactId pendingContactId;
+	private final HandshakeKeys keys;
+
+	public HandshakeKeySet(HandshakeKeySetId keySetId, ContactId contactId,
+			HandshakeKeys keys) {
+		this.keySetId = keySetId;
+		this.contactId = contactId;
+		this.keys = keys;
+		pendingContactId = null;
+	}
+
+	public HandshakeKeySet(HandshakeKeySetId keySetId,
+			PendingContactId pendingContactId, HandshakeKeys keys) {
+		this.keySetId = keySetId;
+		this.pendingContactId = pendingContactId;
+		this.keys = keys;
+		contactId = null;
+	}
+
+	public HandshakeKeySetId getKeySetId() {
+		return keySetId;
+	}
+
+	@Nullable
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	@Nullable
+	public PendingContactId getPendingContactId() {
+		return pendingContactId;
+	}
+
+	public HandshakeKeys getKeys() {
+		return keys;
+	}
+
+	@Override
+	public int hashCode() {
+		return keySetId.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof HandshakeKeySet &&
+				keySetId.equals(((HandshakeKeySet) o).keySetId);
+	}
+}

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

+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Type-safe wrapper for an integer that uniquely identifies a
+ * {@link HandshakeKeySet set of handshake keys} within the scope of the local
+ * device.
+ */
+@Immutable
+@NotNullByDefault
+public class HandshakeKeySetId {
+
+	private final int id;
+
+	public HandshakeKeySetId(int id) {
+		this.id = id;
+	}
+
+	public int getInt() {
+		return id;
+	}
+
+	@Override
+	public int hashCode() {
+		return id;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof HandshakeKeySetId &&
+				id == ((HandshakeKeySetId) o).id;
+	}
+}

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

+package org.briarproject.bramble.api.transport;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Keys for handshaking with a given contact or pending contact over a given
+ * transport. Unlike {@link TransportKeys} these keys do not provide forward
+ * secrecy.
+ */
+@Immutable
+@NotNullByDefault
+public class HandshakeKeys extends AbstractTransportKeys {
+
+	private final SecretKey rootKey;
+	private final boolean alice;
+
+	public HandshakeKeys(TransportId transportId, IncomingKeys inPrev,
+			IncomingKeys inCurr, IncomingKeys inNext, OutgoingKeys outCurr,
+			SecretKey rootKey, boolean alice) {
+		super(transportId, inPrev, inCurr, inNext, outCurr);
+		this.rootKey = rootKey;
+		this.alice = alice;
+	}
+
+	public SecretKey getRootKey() {
+		return rootKey;
+	}
+
+	public boolean isAlice() {
+		return alice;
+	}
+}

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

@@ -9,27 +9,27 @@ import static org.briarproject.bramble.api.transport.TransportConstants.REORDERI
 
 /**
  * Contains transport keys for receiving streams from a given contact over a
- * given transport in a given rotation period.
+ * given transport in a given time period.
  */
 @Immutable
 @NotNullByDefault
 public class IncomingKeys {
 
 	private final SecretKey tagKey, headerKey;
-	private final long rotationPeriod, windowBase;
+	private final long timePeriod, windowBase;
 	private final byte[] windowBitmap;
 
 	public IncomingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod) {
-		this(tagKey, headerKey, rotationPeriod, 0,
+			long timePeriod) {
+		this(tagKey, headerKey, timePeriod, 0,
 				new byte[REORDERING_WINDOW_SIZE / 8]);
 	}
 
 	public IncomingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod, long windowBase, byte[] windowBitmap) {
+			long timePeriod, long windowBase, byte[] windowBitmap) {
 		this.tagKey = tagKey;
 		this.headerKey = headerKey;
-		this.rotationPeriod = rotationPeriod;
+		this.timePeriod = timePeriod;
 		this.windowBase = windowBase;
 		this.windowBitmap = windowBitmap;
 	}
@@ -42,8 +42,8 @@ public class IncomingKeys {
 		return headerKey;
 	}
 
-	public long getRotationPeriod() {
-		return rotationPeriod;
+	public long getTimePeriod() {
+		return timePeriod;
 	}
 
 	public long getWindowBase() {

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

@@ -27,14 +27,14 @@ public interface KeyManager {
 	 * @param alice true if the local party is Alice
 	 * @param active whether the derived keys can be used for outgoing streams
 	 */
-	Map<TransportId, KeySetId> addContact(Transaction txn, ContactId c,
-			SecretKey master, long timestamp, boolean alice, boolean active)
+	Map<TransportId, TransportKeySetId> addContact(Transaction txn, ContactId c,
+			SecretKey rootKey, long timestamp, boolean alice, boolean active)
 			throws DbException;
 
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */
-	void activateKeys(Transaction txn, Map<TransportId, KeySetId> keys)
+	void activateKeys(Transaction txn, Map<TransportId, TransportKeySetId> keys)
 			throws DbException;
 
 	/**

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

@@ -7,26 +7,26 @@ import javax.annotation.concurrent.Immutable;
 
 /**
  * Contains transport keys for sending streams to a given contact over a given
- * transport in a given rotation period.
+ * transport in a given time period.
  */
 @Immutable
 @NotNullByDefault
 public class OutgoingKeys {
 
 	private final SecretKey tagKey, headerKey;
-	private final long rotationPeriod, streamCounter;
+	private final long timePeriod, streamCounter;
 	private final boolean active;
 
 	public OutgoingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod, boolean active) {
-		this(tagKey, headerKey, rotationPeriod, 0, active);
+			long timePeriod, boolean active) {
+		this(tagKey, headerKey, timePeriod, 0, active);
 	}
 
 	public OutgoingKeys(SecretKey tagKey, SecretKey headerKey,
-			long rotationPeriod, long streamCounter, boolean active) {
+			long timePeriod, long streamCounter, boolean active) {
 		this.tagKey = tagKey;
 		this.headerKey = headerKey;
-		this.rotationPeriod = rotationPeriod;
+		this.timePeriod = timePeriod;
 		this.streamCounter = streamCounter;
 		this.active = active;
 	}
@@ -39,8 +39,8 @@ public class OutgoingKeys {
 		return headerKey;
 	}
 
-	public long getRotationPeriod() {
-		return rotationPeriod;
+	public long getTimePeriod() {
+		return timePeriod;
 	}
 
 	public long getStreamCounter() {

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

@@ -82,30 +82,58 @@ public interface TransportConstants {
 	int REORDERING_WINDOW_SIZE = 32;
 
 	/**
-	 * Label for deriving Alice's initial tag key from the master secret.
+	 * Label for deriving Alice's initial tag key from the root key in
+	 * rotation mode.
 	 */
 	String ALICE_TAG_LABEL = "org.briarproject.bramble.transport/ALICE_TAG_KEY";
 
 	/**
-	 * Label for deriving Bob's initial tag key from the master secret.
+	 * Label for deriving Bob's initial tag key from the root key in rotation
+	 * mode.
 	 */
 	String BOB_TAG_LABEL = "org.briarproject.bramble.transport/BOB_TAG_KEY";
 
 	/**
-	 * Label for deriving Alice's initial header key from the master secret.
+	 * Label for deriving Alice's initial header key from the root key in
+	 * rotation mode.
 	 */
 	String ALICE_HEADER_LABEL =
 			"org.briarproject.bramble.transport/ALICE_HEADER_KEY";
 
 	/**
-	 * Label for deriving Bob's initial header key from the master secret.
+	 * Label for deriving Bob's initial header key from the root key in
+	 * rotation mode.
 	 */
 	String BOB_HEADER_LABEL =
 			"org.briarproject.bramble.transport/BOB_HEADER_KEY";
 
 	/**
-	 * Label for deriving the next period's key in key rotation.
+	 * Label for deriving the next period's key in rotation mode.
 	 */
 	String ROTATE_LABEL = "org.briarproject.bramble.transport/ROTATE";
 
+	/**
+	 * Label for deriving Alice's tag key from the root key in handshake mode.
+	 */
+	String ALICE_HANDSHAKE_TAG_LABEL =
+			"org.briarproject.bramble.transport/ALICE_HANDSHAKE_TAG_KEY";
+
+	/**
+	 * Label for deriving Bob's tag key from the root key in handshake mode.
+	 */
+	String BOB_HANDSHAKE_TAG_LABEL =
+			"org.briarproject.bramble.transport/BOB_HANDSHAKE_TAG_KEY";
+
+	/**
+	 * Label for deriving Alice's header key from the root key in handshake
+	 * mode.
+	 */
+	String ALICE_HANDSHAKE_HEADER_LABEL =
+			"org.briarproject.bramble.transport/ALICE_HANDSHAKE_HEADER_KEY";
+
+	/**
+	 * Label for deriving Bob's header key from the root key in handshake mode.
+	 */
+	String BOB_HANDSHAKE_HEADER_LABEL =
+			"org.briarproject.bramble.transport/BOB_HANDSHAKE_HEADER_KEY";
 }

bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySet.java → bramble-api/src/main/java/org/briarproject/bramble/api/transport/TransportKeySet.java

@@ -6,24 +6,25 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * A set of transport keys for communicating with a contact.
+ * A set of keys for communicating with a given contact over a given transport.
+ * Unlike a {@link HandshakeKeySet} these keys provide forward secrecy.
  */
 @Immutable
 @NotNullByDefault
-public class KeySet {
+public class TransportKeySet {
 
-	private final KeySetId keySetId;
+	private final TransportKeySetId keySetId;
 	private final ContactId contactId;
-	private final TransportKeys transportKeys;
+	private final TransportKeys keys;
 
-	public KeySet(KeySetId keySetId, ContactId contactId,
-			TransportKeys transportKeys) {
+	public TransportKeySet(TransportKeySetId keySetId, ContactId contactId,
+			TransportKeys keys) {
 		this.keySetId = keySetId;
 		this.contactId = contactId;
-		this.transportKeys = transportKeys;
+		this.keys = keys;
 	}
 
-	public KeySetId getKeySetId() {
+	public TransportKeySetId getKeySetId() {
 		return keySetId;
 	}
 
@@ -31,8 +32,8 @@ public class KeySet {
 		return contactId;
 	}
 
-	public TransportKeys getTransportKeys() {
-		return transportKeys;
+	public TransportKeys getKeys() {
+		return keys;
 	}
 
 	@Override
@@ -42,6 +43,7 @@ public class KeySet {
 
 	@Override
 	public boolean equals(Object o) {
-		return o instanceof KeySet && keySetId.equals(((KeySet) o).keySetId);
+		return o instanceof TransportKeySet &&
+				keySetId.equals(((TransportKeySet) o).keySetId);
 	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeySetId.java → bramble-api/src/main/java/org/briarproject/bramble/api/transport/TransportKeySetId.java

@@ -5,18 +5,19 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * Type-safe wrapper for an integer that uniquely identifies a set of transport
- * keys within the scope of the local device.
+ * Type-safe wrapper for an integer that uniquely identifies a
+ * {@link TransportKeySet set of transport keys} within the scope of the local
+ * device.
  * <p/>
  * Key sets created on a given device must have increasing identifiers.
  */
 @Immutable
 @NotNullByDefault
-public class KeySetId {
+public class TransportKeySetId {
 
 	private final int id;
 
-	public KeySetId(int id) {
+	public TransportKeySetId(int id) {
 		this.id = id;
 	}
 
@@ -31,6 +32,7 @@ public class KeySetId {
 
 	@Override
 	public boolean equals(Object o) {
-		return o instanceof KeySetId && id == ((KeySetId) o).id;
+		return o instanceof TransportKeySetId &&
+				id == ((TransportKeySetId) o).id;
 	}
 }