private KeyExchangeMessage processInitiate(KeyExchangeMessage message)
{
uint flags = KeyExchangeMessage.RESPONSE_FLAG;
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
if (!Curve.verifySignature(message.getIdentityKey().getPublicKey(),
message.getBaseKey().serialize(),
message.getBaseKeySignature()))
{
throw new InvalidKeyException("Bad signature!");
}
SymmetricSignalProtocolParameters.Builder builder = SymmetricSignalProtocolParameters.newBuilder();
if (!sessionRecord.getSessionState().hasPendingKeyExchange())
{
builder.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setOurBaseKey(Curve.generateKeyPair())
.setOurRatchetKey(Curve.generateKeyPair());
}
else
{
builder.setOurIdentityKey(sessionRecord.getSessionState().getPendingKeyExchangeIdentityKey())
.setOurBaseKey(sessionRecord.getSessionState().getPendingKeyExchangeBaseKey())
.setOurRatchetKey(sessionRecord.getSessionState().getPendingKeyExchangeRatchetKey());
flags |= KeyExchangeMessage.SIMULTAENOUS_INITIATE_FLAG;
}
builder.setTheirBaseKey(message.getBaseKey())
.setTheirRatchetKey(message.getRatchetKey())
.setTheirIdentityKey(message.getIdentityKey());
SymmetricSignalProtocolParameters parameters = builder.create();
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
parameters);
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), message.getIdentityKey());
byte[] baseKeySignature = Curve.calculateSignature(parameters.getOurIdentityKey().getPrivateKey(),
parameters.getOurBaseKey().getPublicKey().serialize());
return(new KeyExchangeMessage(sessionRecord.getSessionState().getSessionVersion(),
message.getSequence(), flags,
parameters.getOurBaseKey().getPublicKey(),
baseKeySignature, parameters.getOurRatchetKey().getPublicKey(),
parameters.getOurIdentityKey().getPublicKey()));
}
private void processResponse(KeyExchangeMessage message)
{
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
SessionState sessionState = sessionRecord.getSessionState();
bool hasPendingKeyExchange = sessionState.hasPendingKeyExchange();
bool isSimultaneousInitiateResponse = message.isResponseForSimultaneousInitiate();
if (!hasPendingKeyExchange || sessionState.getPendingKeyExchangeSequence() != message.getSequence())
{
Debug.WriteLine("No matching sequence for response. Is simultaneous initiate response: " + isSimultaneousInitiateResponse);
if (!isSimultaneousInitiateResponse)
{
throw new StaleKeyExchangeException();
}
else
{
return;
}
}
SymmetricSignalProtocolParameters.Builder parameters = SymmetricSignalProtocolParameters.newBuilder();
parameters.setOurBaseKey(sessionRecord.getSessionState().getPendingKeyExchangeBaseKey())
.setOurRatchetKey(sessionRecord.getSessionState().getPendingKeyExchangeRatchetKey())
.setOurIdentityKey(sessionRecord.getSessionState().getPendingKeyExchangeIdentityKey())
.setTheirBaseKey(message.getBaseKey())
.setTheirRatchetKey(message.getRatchetKey())
.setTheirIdentityKey(message.getIdentityKey());
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(), parameters.create());
if (!Curve.verifySignature(message.getIdentityKey().getPublicKey(),
message.getBaseKey().serialize(),
message.getBaseKeySignature()))
{
throw new InvalidKeyException("Base key signature doesn't match!");
}
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), message.getIdentityKey());
}