Migrate Bluetooth protocol to BQP's master secret derivation

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

@@ -29,14 +29,6 @@ public interface CryptoComponent {
 	/** Generates a random invitation code. */
 	int generateBTInvitationCode();
 
-	/**
-	 * Derives a shared master secret from two public keys and one of the
-	 * corresponding private keys.
-	 * @param alice whether the private key belongs to Alice or Bob.
-	 */
-	SecretKey deriveBTMasterSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
-			boolean alice) throws GeneralSecurityException;
-
 	/**
 	 * Derives a confirmation code from the given master secret.
 	 * @param alice whether the code is for use by Alice or Bob.
@@ -111,6 +103,22 @@ public interface CryptoComponent {
 	 */
 	SecretKey deriveMasterSecret(SecretKey sharedSecret);
 
+	/**
+	 * 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
+	 * deriveMasterSecret(deriveSharedSecret(theirPublicKey, ourKeyPair, alice))
+	 *
+	 * @param theirPublicKey the ephemeral public key of the remote party
+	 * @param ourKeyPair our ephemeral keypair
+	 * @param alice true if ourKeyPair belongs to Alice
+	 * @return the shared secret
+	 * @throws GeneralSecurityException
+	 */
+	SecretKey deriveMasterSecret(byte[] theirPublicKey, KeyPair ourKeyPair,
+			boolean alice) throws GeneralSecurityException;
+
 	/**
 	 * Derives initial transport keys for the given transport in the given
 	 * rotation period from the given master secret.

briar-core/src/org/briarproject/crypto/CryptoComponentImpl.java

@@ -205,28 +205,6 @@ class CryptoComponentImpl implements CryptoComponent {
 		return ByteUtils.readUint(random, CODE_BITS);
 	}
 
-	public SecretKey deriveBTMasterSecret(byte[] theirPublicKey,
-			KeyPair ourKeyPair, boolean alice) throws GeneralSecurityException {
-		MessageDigest messageDigest = getMessageDigest();
-		byte[] ourPublicKey = ourKeyPair.getPublic().getEncoded();
-		byte[] ourHash = messageDigest.digest(ourPublicKey);
-		byte[] theirHash = messageDigest.digest(theirPublicKey);
-		byte[] aliceInfo, bobInfo;
-		if (alice) {
-			aliceInfo = ourHash;
-			bobInfo = theirHash;
-		} else {
-			aliceInfo = theirHash;
-			bobInfo = ourHash;
-		}
-		PrivateKey ourPriv = ourKeyPair.getPrivate();
-		PublicKey theirPub = agreementKeyParser.parsePublicKey(theirPublicKey);
-		// The raw secret comes from the key agreement algorithm
-		byte[] raw = performRawKeyAgreement(ourPriv, theirPub);
-		// Derive the master secret from the raw secret using the hash KDF
-		return new SecretKey(hashKdf(raw, BT_MASTER, aliceInfo, bobInfo));
-	}
-
 	public int deriveBTConfirmationCode(SecretKey master, boolean alice) {
 		byte[] b = macKdf(master, alice ? BT_A_CONFIRM : BT_B_CONFIRM);
 		return ByteUtils.readUint(b, CODE_BITS);
@@ -290,6 +268,12 @@ class CryptoComponentImpl implements CryptoComponent {
 		return new SecretKey(macKdf(sharedSecret, MASTER_KEY));
 	}
 
+	public SecretKey deriveMasterSecret(byte[] theirPublicKey,
+			KeyPair ourKeyPair, boolean alice) throws GeneralSecurityException {
+		return deriveMasterSecret(deriveSharedSecret(
+				theirPublicKey,ourKeyPair, alice));
+	}
+
 	public TransportKeys deriveTransportKeys(TransportId t,
 			SecretKey master, long rotationPeriod, boolean alice) {
 		// Keys for the previous period are derived from the master secret

briar-core/src/org/briarproject/invitation/Connector.java

@@ -146,7 +146,7 @@ abstract class Connector extends Thread {
 		//  Derive the master secret
 		if (LOG.isLoggable(INFO))
 			LOG.info(pluginName + " deriving master secret");
-		return crypto.deriveBTMasterSecret(key, keyPair, alice);
+		return crypto.deriveMasterSecret(key, keyPair, alice);
 	}
 
 	protected void sendConfirmation(BdfWriter w, boolean confirmed)

briar-tests/src/org/briarproject/crypto/KeyAgreementTest.java

@@ -20,8 +20,8 @@ public class KeyAgreementTest extends BriarTestCase {
 		byte[] aPub = aPair.getPublic().getEncoded();
 		KeyPair bPair = crypto.generateAgreementKeyPair();
 		byte[] bPub = bPair.getPublic().getEncoded();
-		SecretKey aMaster = crypto.deriveBTMasterSecret(aPub, bPair, true);
+		SecretKey aMaster = crypto.deriveMasterSecret(aPub, bPair, true);
-		SecretKey bMaster = crypto.deriveBTMasterSecret(bPub, aPair, false);
+		SecretKey bMaster = crypto.deriveMasterSecret(bPub, aPair, false);
 		assertArrayEquals(aMaster.getBytes(), bMaster.getBytes());
 	}