private void handleRevealSignatureMessage(RevealSignatureMessage m) throws OtrException {
Session session = getSession();
SessionID sessionID = session.getSessionID();
logger.finest(
sessionID.getLocalUserId()
+ " received a reveal signature message from "
+ sessionID.getRemoteUserId()
+ " throught "
+ sessionID.getProtocolName()
+ ".");
if (!session.getSessionPolicy().getAllowV2()) {
logger.finest("Policy does not allow OTRv2, ignoring message.");
return;
}
switch (this.getAuthenticationState()) {
case AWAITING_REVEALSIG:
// Use the received value of r to decrypt the value of gx
// received
// in the D-H Commit Message, and verify the hash therein.
// Decrypt
// the encrypted signature, and verify the signature and the
// MACs.
// If everything checks out:
// * Reply with a Signature Message.
// * Transition authstate to AUTHSTATE_NONE.
// * Transition msgstate to MSGSTATE_ENCRYPTED.
// * TODO If there is a recent stored message, encrypt it and
// send
// it as a Data Message.
OtrCryptoEngine otrCryptoEngine = new OtrCryptoEngineImpl();
// Uses r to decrypt the value of gx sent earlier
byte[] remoteDHPublicKeyDecrypted =
otrCryptoEngine.aesDecrypt(m.revealedKey, null, this.getRemoteDHPublicKeyEncrypted());
// Verifies that HASH(gx) matches the value sent earlier
byte[] remoteDHPublicKeyHash = otrCryptoEngine.sha256Hash(remoteDHPublicKeyDecrypted);
if (!Arrays.equals(remoteDHPublicKeyHash, this.getRemoteDHPublicKeyHash())) {
logger.finest("Hashes don't match, ignoring message.");
return;
}
// Verifies that Bob's gx is a legal value (2 <= gx <=
// modulus-2)
BigInteger remoteDHPublicKeyMpi;
try {
remoteDHPublicKeyMpi = SerializationUtils.readMpi(remoteDHPublicKeyDecrypted);
} catch (IOException e) {
throw new OtrException(e);
}
this.setRemoteDHPublicKey(otrCryptoEngine.getDHPublicKey(remoteDHPublicKeyMpi));
// Verify received Data.
if (!m.verify(this.getM2())) {
logger.finest("Signature MACs are not equal, ignoring message.");
return;
}
// Decrypt X.
byte[] remoteXDecrypted = m.decrypt(this.getC());
SignatureX remoteX;
try {
remoteX = SerializationUtils.toMysteriousX(remoteXDecrypted);
} catch (IOException e) {
throw new OtrException(e);
}
// Compute signature.
PublicKey remoteLongTermPublicKey = remoteX.longTermPublicKey;
SignatureM remoteM =
new SignatureM(
this.getRemoteDHPublicKey(),
(DHPublicKey) this.getLocalDHKeyPair().getPublic(),
remoteLongTermPublicKey,
remoteX.dhKeyID);
// Verify signature.
byte[] signature;
try {
signature =
otrCryptoEngine.sha256Hmac(SerializationUtils.toByteArray(remoteM), this.getM1());
} catch (IOException e) {
throw new OtrException(e);
}
if (!otrCryptoEngine.verify(signature, remoteLongTermPublicKey, remoteX.signature)) {
session.showWarning("Bad revealed signature");
logger.finest("Signature verification failed.");
return;
}
logger.finest("Signature verification succeeded.");
this.setAuthenticationState(AuthContext.NONE);
this.setIsSecure(true);
this.setRemoteLongTermPublicKey(remoteLongTermPublicKey);
getSession().injectMessage(messageFactory.getSignatureMessage());
break;
default:
logger.finest("Ignoring message.");
break;
}
}
private void handleSignatureMessage(SignatureMessage m) throws OtrException {
Session session = getSession();
SessionID sessionID = session.getSessionID();
logger.finest(
sessionID.getLocalUserId()
+ " received a signature message from "
+ sessionID.getRemoteUserId()
+ " throught "
+ sessionID.getProtocolName()
+ ".");
if (!session.getSessionPolicy().getAllowV2()) {
logger.finest("Policy does not allow OTRv2, ignoring message.");
return;
}
switch (this.getAuthenticationState()) {
case AWAITING_SIG:
// Verify MAC.
if (!m.verify(this.getM2p())) {
logger.finest("Signature MACs are not equal, ignoring message.");
return;
}
// Decrypt X.
byte[] remoteXDecrypted = m.decrypt(this.getCp());
SignatureX remoteX;
try {
remoteX = SerializationUtils.toMysteriousX(remoteXDecrypted);
} catch (IOException e) {
throw new OtrException(e);
}
// Compute signature.
PublicKey remoteLongTermPublicKey = remoteX.longTermPublicKey;
SignatureM remoteM =
new SignatureM(
this.getRemoteDHPublicKey(),
(DHPublicKey) this.getLocalDHKeyPair().getPublic(),
remoteLongTermPublicKey,
remoteX.dhKeyID);
OtrCryptoEngine otrCryptoEngine = new OtrCryptoEngineImpl();
// Verify signature.
byte[] signature;
try {
signature =
otrCryptoEngine.sha256Hmac(SerializationUtils.toByteArray(remoteM), this.getM1p());
} catch (IOException e) {
throw new OtrException(e);
}
if (!otrCryptoEngine.verify(signature, remoteLongTermPublicKey, remoteX.signature)) {
session.showWarning("Bad signature");
logger.finest("Signature verification failed.");
return;
}
this.setIsSecure(true);
this.setRemoteLongTermPublicKey(remoteLongTermPublicKey);
break;
default:
logger.finest("We were not expecting a signature, ignoring message.");
return;
}
}