def processInitiate(self, keyExchangeMessage):
flags = KeyExchangeMessage.RESPONSE_FLAG
sessionRecord = self.sessionStore.loadSession(self.recipientId, self.deviceId)
if keyExchangeMessage.getVersion() >= 3 and not Curve.verifySignature(
keyExchangeMessage.getIdentityKey().getPublicKey(),
keyExchangeMessage.getBaseKey().serialize(),
keyExchangeMessage.getBaseKeySignature()):
raise InvalidKeyException("Bad signature!")
builder = SymmetricAxolotlParameters.newBuilder()
if not sessionRecord.getSessionState().hasPendingKeyExchange():
builder.setOurIdentityKey(self.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(keyExchangeMessage.getBaseKey())\
.setTheirRatchetKey(keyExchangeMessage.getRatchetKey())\
.setTheirIdentityKey(keyExchangeMessage.getIdentityKey())
parameters = builder.create()
if not sessionRecord.isFresh(): sessionRecord.archiveCurrentState()
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
min(keyExchangeMessage.getMaxVersion(), CiphertextMessage.CURRENT_VERSION),
parameters)
self.sessionStore.storeSession(self.recipientId, self.deviceId, sessionRecord)
self.identityKeyStore.saveIdentity(self.recipientId, keyExchangeMessage.getIdentityKey())
baseKeySignature = Curve.calculateSignature(parameters.getOurIdentityKey().getPrivateKey(),
parameters.getOurBaseKey().getPublicKey().serialize())
return KeyExchangeMessage(sessionRecord.getSessionState().getSessionVersion(),
keyExchangeMessage.getSequence(), flags,
parameters.getOurBaseKey().getPublicKey(),
baseKeySignature, parameters.getOurRatchetKey().getPublicKey(),
parameters.getOurIdentityKey().getPublicKey())
def processResponse(self, keyExchangeMessage):
sessionRecord = self.sessionStore.loadSession(self.recipientId, self.deviceId)
sessionState = sessionRecord.getSessionState()
hasPendingKeyExchange = sessionState.hasPendingKeyExchange()
isSimultaneousInitiateResponse = keyExchangeMessage.isResponseForSimultaneousInitiate()
if not hasPendingKeyExchange or sessionState.getPendingKeyExchangeSequence() != keyExchangeMessage.getSequence():
logger.warn("No matching sequence for response. Is simultaneous initiate response: %s" % isSimultaneousInitiateResponse)
if not isSimultaneousInitiateResponse:
raise StaleKeyExchangeException()
else:
return
parameters = SymmetricAxolotlParameters.newBuilder()
parameters.setOurBaseKey(sessionRecord.getSessionState().getPendingKeyExchangeBaseKey())\
.setOurRatchetKey(sessionRecord.getSessionState().getPendingKeyExchangeRatchetKey())\
.setOurIdentityKey(sessionRecord.getSessionState().getPendingKeyExchangeIdentityKey())\
.setTheirBaseKey(keyExchangeMessage.getBaseKey())\
.setTheirRatchetKey(keyExchangeMessage.getRatchetKey())\
.setTheirIdentityKey(keyExchangeMessage.getIdentityKey())
if not sessionRecord.isFresh(): sessionRecord.archiveCurrentState()
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
min(keyExchangeMessage.getMaxVersion(), CiphertextMessage.CURRENT_VERSION),
parameters.create())
if sessionRecord.getSessionState().getSessionVersion() >= 3 and not Curve.verifySignature(
keyExchangeMessage.getIdentityKey().getPublicKey(),
keyExchangeMessage.getBaseKey().serialize(),
keyExchangeMessage.getBaseKeySignature()):
raise InvalidKeyException("Base key signature doesn't match!")
self.sessionStore.storeSession(self.recipientId, self.deviceId, sessionRecord)
self.identityKeyStore.saveIdentity(self.recipientId, keyExchangeMessage.getIdentityKey())
