Merge branch '117-qr-contacts' into 'master'

BQP with QR codes

This MR implements BQP for key agreement over short-range transports. It also implements the Android UI for using BQP with QR codes.

Closes #117.

See merge request !84

briar-api/src/org/briarproject/api/contact/ContactExchangeListener.java

@@ -0,0 +1,14 @@
+package org.briarproject.api.contact;
+
+import org.briarproject.api.identity.Author;
+
+public interface ContactExchangeListener {
+
+	void contactExchangeSucceeded(Author remoteAuthor);
+
+	/** The exchange failed because the contact already exists. */
+	void duplicateContact(Author remoteAuthor);
+
+	/** A general failure. */
+	void contactExchangeFailed();
+}

briar-api/src/org/briarproject/api/contact/ContactExchangeTask.java

@@ -0,0 +1,20 @@
+package org.briarproject.api.contact;
+
+import org.briarproject.api.TransportId;
+import org.briarproject.api.crypto.SecretKey;
+import org.briarproject.api.identity.LocalAuthor;
+import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
+
+/**
+ * A task for conducting a contact information exchange with a remote peer.
+ */
+public interface ContactExchangeTask {
+
+	/**
+	 * Exchange contact information with a remote peer.
+	 */
+	void startExchange(ContactExchangeListener listener,
+			LocalAuthor localAuthor, SecretKey masterSecret,
+			DuplexTransportConnection conn, TransportId transportId,
+			boolean alice);
+}

briar-api/src/org/briarproject/api/crypto/CryptoComponent.java

@@ -36,18 +36,17 @@ public interface CryptoComponent {
 	int deriveBTConfirmationCode(SecretKey master, boolean alice);
 
 	/**
-	 * Derives a header key for an invitation stream from the given master
-	 * secret.
+	 * Derives a stream header key from the given master secret.
 	 * @param alice whether the key is for use by Alice or Bob.
 	 */
-	SecretKey deriveBTInvitationKey(SecretKey master, boolean alice);
+	SecretKey deriveHeaderKey(SecretKey master, boolean alice);
 
 	/**
 	 * Derives a nonce from the given master secret for one of the parties to
 	 * sign.
 	 * @param alice whether the nonce is for use by Alice or Bob.
 	 */
-	byte[] deriveBTSignatureNonce(SecretKey master, boolean alice);
+	byte[] deriveSignatureNonce(SecretKey master, boolean alice);
 
 	/**
 	 * Derives a commitment to the provided public key.
@@ -107,7 +106,7 @@ public interface CryptoComponent {
 	 * Derives a master secret from two public keys and one of the corresponding
 	 * private keys.
 	 * <p/>
-	 * Part of BQP. This is a helper method that calls
+	 * This is a helper method that calls
 	 * deriveMasterSecret(deriveSharedSecret(theirPublicKey, ourKeyPair, alice))
 	 *
 	 * @param theirPublicKey the ephemeral public key of the remote party

briar-api/src/org/briarproject/api/event/KeyAgreementAbortedEvent.java

@@ -0,0 +1,15 @@
+package org.briarproject.api.event;
+
+/** An event that is broadcast when a BQP protocol aborts. */
+public class KeyAgreementAbortedEvent extends Event {
+
+	private final boolean remoteAborted;
+
+	public KeyAgreementAbortedEvent(boolean remoteAborted) {
+		this.remoteAborted = remoteAborted;
+	}
+
+	public boolean didRemoteAbort() {
+		return remoteAborted;
+	}
+}

briar-api/src/org/briarproject/api/event/KeyAgreementFailedEvent.java

@@ -0,0 +1,6 @@
+package org.briarproject.api.event;
+
+/** An event that is broadcast when a BQP connection cannot be created. */
+public class KeyAgreementFailedEvent extends Event {
+
+}

briar-api/src/org/briarproject/api/event/KeyAgreementFinishedEvent.java

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.keyagreement.KeyAgreementResult;
+
+/** An event that is broadcast when a BQP protocol completes. */
+public class KeyAgreementFinishedEvent extends Event {
+
+	private final KeyAgreementResult result;
+
+	public KeyAgreementFinishedEvent(KeyAgreementResult result) {
+		this.result = result;
+	}
+
+	public KeyAgreementResult getResult() {
+		return result;
+	}
+}

briar-api/src/org/briarproject/api/event/KeyAgreementListeningEvent.java

@@ -0,0 +1,17 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.keyagreement.Payload;
+
+/** An event that is broadcast when a BQP task is listening. */
+public class KeyAgreementListeningEvent extends Event {
+
+	private final Payload localPayload;
+
+	public KeyAgreementListeningEvent(Payload localPayload) {
+		this.localPayload = localPayload;
+	}
+
+	public Payload getLocalPayload() {
+		return localPayload;
+	}
+}

briar-api/src/org/briarproject/api/event/KeyAgreementStartedEvent.java

@@ -0,0 +1,6 @@
+package org.briarproject.api.event;
+
+/** An event that is broadcast when a BQP protocol completes. */
+public class KeyAgreementStartedEvent extends Event {
+
+}

briar-api/src/org/briarproject/api/event/KeyAgreementWaitingEvent.java

@@ -0,0 +1,9 @@
+package org.briarproject.api.event;
+
+/**
+ * An event that is broadcast when a BQP protocol is waiting on the remote
+ * peer to start.
+ */
+public class KeyAgreementWaitingEvent extends Event {
+
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementConnection.java

@@ -0,0 +1,23 @@
+package org.briarproject.api.keyagreement;
+
+import org.briarproject.api.TransportId;
+import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
+
+public class KeyAgreementConnection {
+	private final DuplexTransportConnection conn;
+	private final TransportId id;
+
+	public KeyAgreementConnection(DuplexTransportConnection conn,
+			TransportId id) {
+		this.conn = conn;
+		this.id = id;
+	}
+
+	public DuplexTransportConnection getConnection() {
+		return conn;
+	}
+
+	public TransportId getTransportId() {
+		return id;
+	}
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementConstants.java

@@ -3,6 +3,17 @@ package org.briarproject.api.keyagreement;
 
 public interface KeyAgreementConstants {
 
+	/** The current version of the BQP protocol. */
+	byte PROTOCOL_VERSION = 1;
+
+	/** The length of the record header in bytes. */
+	int RECORD_HEADER_LENGTH = 4;
+
+	/** The offset of the payload length in the record header, in bytes. */
+	int RECORD_HEADER_PAYLOAD_LENGTH_OFFSET = 2;
+
 	/** The length of the BQP key commitment in bytes. */
 	int COMMIT_LENGTH = 16;
+
+	long CONNECTION_TIMEOUT = 20 * 1000; // Milliseconds
 }

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementListener.java

@@ -0,0 +1,35 @@
+package org.briarproject.api.keyagreement;
+
+import java.util.concurrent.Callable;
+
+/**
+ * An class for managing a particular key agreement listener.
+ */
+public abstract class KeyAgreementListener {
+
+	private final TransportDescriptor descriptor;
+
+	public KeyAgreementListener(TransportDescriptor descriptor) {
+		this.descriptor = descriptor;
+	}
+
+	/**
+	 * Returns the descriptor that a remote peer can use to connect to this
+	 * listener.
+	 */
+	public TransportDescriptor getDescriptor() {
+		return descriptor;
+	}
+
+	/**
+	 * Starts listening for incoming connections, and returns a Callable that
+	 * will return a KeyAgreementConnection when an incoming connection is
+	 * received.
+	 */
+	public abstract Callable<KeyAgreementConnection> listen();
+
+	/**
+	 * Closes the underlying server socket.
+	 */
+	public abstract void close();
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementResult.java

@@ -0,0 +1,38 @@
+package org.briarproject.api.keyagreement;
+
+import org.briarproject.api.TransportId;
+import org.briarproject.api.crypto.SecretKey;
+import org.briarproject.api.plugins.duplex.DuplexTransportConnection;
+
+public class KeyAgreementResult {
+
+	private final SecretKey masterKey;
+	private final DuplexTransportConnection connection;
+	private final TransportId transportId;
+	private final boolean alice;
+
+	public KeyAgreementResult(SecretKey masterKey,
+			DuplexTransportConnection connection, TransportId transportId,
+			boolean alice) {
+		this.masterKey = masterKey;
+		this.connection = connection;
+		this.transportId = transportId;
+		this.alice = alice;
+	}
+
+	public SecretKey getMasterKey() {
+		return masterKey;
+	}
+
+	public DuplexTransportConnection getConnection() {
+		return connection;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public boolean wasAlice() {
+		return alice;
+	}
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementTask.java

@@ -0,0 +1,21 @@
+package org.briarproject.api.keyagreement;
+
+/** A task for conducting a key agreement with a remote peer. */
+public interface KeyAgreementTask {
+
+	/**
+	 * Start listening for short-range BQP connections, if we are not already.
+	 * <p/>
+	 * Will trigger a KeyAgreementListeningEvent containing the local Payload,
+	 * even if we are already listening.
+	 */
+	void listen();
+
+	/**
+	 * Stop listening for short-range BQP connections.
+	 */
+	void stopListening();
+
+	/** Asynchronously start the connection process. */
+	void connectAndRunProtocol(Payload remotePayload);
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementTaskFactory.java

@@ -0,0 +1,8 @@
+package org.briarproject.api.keyagreement;
+
+/** Manages tasks for conducting key agreements with remote peers. */
+public interface KeyAgreementTaskFactory {
+
+	/** Gets the current key agreement task. */
+	KeyAgreementTask getTask();
+}

briar-api/src/org/briarproject/api/keyagreement/KeyAgreementTaskId.java

@@ -0,0 +1,18 @@
+package org.briarproject.api.keyagreement;
+
+import org.briarproject.api.UniqueId;
+
+/**
+ * Type-safe wrapper for a byte array that uniquely identifies a BQP task.
+ */
+public class KeyAgreementTaskId extends UniqueId {
+
+	public KeyAgreementTaskId(byte[] id) {
+		super(id);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		return o instanceof KeyAgreementTaskId && super.equals(o);
+	}
+}

briar-api/src/org/briarproject/api/keyagreement/Payload.java

@@ -0,0 +1,34 @@
+package org.briarproject.api.keyagreement;
+
+import org.briarproject.api.Bytes;
+
+import java.util.List;
+
+/**
+ * A BQP payload.
+ */
+public class Payload implements Comparable<Payload> {
+
+	private final Bytes commitment;
+	private final List<TransportDescriptor> descriptors;
+
+	public Payload(byte[] commitment, List<TransportDescriptor> descriptors) {
+		this.commitment = new Bytes(commitment);
+		this.descriptors = descriptors;
+	}
+
+	/** Returns the commitment contained in this payload. */
+	public byte[] getCommitment() {
+		return commitment.getBytes();
+	}
+
+	/** Returns the transport descriptors contained in this payload. */
+	public List<TransportDescriptor> getTransportDescriptors() {
+		return descriptors;
+	}
+
+	@Override
+	public int compareTo(Payload p) {
+		return commitment.compareTo(p.commitment);
+	}
+}

briar-api/src/org/briarproject/api/keyagreement/PayloadEncoder.java

@@ -0,0 +1,6 @@
+package org.briarproject.api.keyagreement;
+
+public interface PayloadEncoder {
+
+	byte[] encode(Payload p);
+}

briar-api/src/org/briarproject/api/keyagreement/PayloadParser.java

@@ -0,0 +1,8 @@
+package org.briarproject.api.keyagreement;
+
+import java.io.IOException;
+
+public interface PayloadParser {
+
+	Payload parse(byte[] raw) throws IOException;
+}

briar-api/src/org/briarproject/api/keyagreement/RecordTypes.java

@@ -0,0 +1,9 @@
+package org.briarproject.api.keyagreement;
+
+/** Record types for BQP. */
+public interface RecordTypes {
+
+	byte KEY = 0;
+	byte CONFIRM = 1;
+	byte ABORT = 2;
+}

briar-api/src/org/briarproject/api/keyagreement/TransportDescriptor.java

@@ -0,0 +1,28 @@
+package org.briarproject.api.keyagreement;
+
+import org.briarproject.api.TransportId;
+import org.briarproject.api.properties.TransportProperties;
+
+/**
+ * Describes how to connect to a device over a short-range transport.
+ */
+public class TransportDescriptor {
+
+	private final TransportId id;
+	private final TransportProperties properties;
+
+	public TransportDescriptor(TransportId id, TransportProperties properties) {
+		this.id = id;
+		this.properties = properties;
+	}
+
+	/** Returns the transport identifier. */
+	public TransportId getIdentifier() {
+		return id;
+	}
+
+	/** Returns the transport properties. */
+	public TransportProperties getProperties() {
+		return properties;
+	}
+}

briar-api/src/org/briarproject/api/plugins/PluginManager.java

@@ -19,4 +19,7 @@ public interface PluginManager {
 
 	/** Returns any running duplex plugins that support invitations. */
 	Collection<DuplexPlugin> getInvitationPlugins();
+
+	/** Returns any running duplex plugins that support key agreement. */
+	Collection<DuplexPlugin> getKeyAgreementPlugins();
 }

briar-api/src/org/briarproject/api/plugins/duplex/DuplexPlugin.java

@@ -2,6 +2,8 @@ package org.briarproject.api.plugins.duplex;
 
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.crypto.PseudoRandom;
+import org.briarproject.api.keyagreement.KeyAgreementListener;
+import org.briarproject.api.keyagreement.TransportDescriptor;
 import org.briarproject.api.plugins.Plugin;
 
 /** An interface for transport plugins that support duplex communication. */
@@ -24,4 +26,19 @@ public interface DuplexPlugin extends Plugin {
 	 */
 	DuplexTransportConnection createInvitationConnection(PseudoRandom r,
 			long timeout, boolean alice);
+
+	/** Returns true if the plugin supports short-range key agreement. */
+	boolean supportsKeyAgreement();
+
+	/**
+	 * Returns a listener that can be used to perform key agreement.
+	 */
+	KeyAgreementListener createKeyAgreementListener(byte[] localCommitment);
+
+	/**
+	 * Attempts to connect to the remote peer specified in the given descriptor.
+	 * Returns null if no connection can be established within the given time.
+	 */
+	DuplexTransportConnection createKeyAgreementConnection(
+			byte[] remoteCommitment, TransportDescriptor d, long timeout);
 }