/**
* Build a new session from a {@link org.whispersystems.libaxolotl.state.PreKeyBundle} retrieved from
* a server.
*
* @param preKey A PreKey for the destination recipient, retrieved from a server.
* @throws InvalidKeyException when the {@link org.whispersystems.libaxolotl.state.PreKeyBundle} is
* badly formatted.
* @throws org.whispersystems.libaxolotl.UntrustedIdentityException when the sender's
* {@link IdentityKey} is not
* trusted.
*/
public void process(PreKeyBundle preKey)
{
lock (SessionCipher.SESSION_LOCK)
{
if (!identityKeyStore.IsTrustedIdentity(remoteAddress.getName(), preKey.getIdentityKey()))
{
throw new UntrustedIdentityException(remoteAddress.getName(), preKey.getIdentityKey());
}
if (preKey.getSignedPreKey() != null &&
!Curve.verifySignature(preKey.getIdentityKey().getPublicKey(),
preKey.getSignedPreKey().serialize(),
preKey.getSignedPreKeySignature()))
{
throw new InvalidKeyException("Invalid signature on device key!");
}
if (preKey.getSignedPreKey() == null && preKey.getPreKey() == null)
{
throw new InvalidKeyException("Both signed and unsigned prekeys are absent!");
}
bool supportsV3 = preKey.getSignedPreKey() != null;
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
ECKeyPair ourBaseKey = Curve.generateKeyPair();
ECPublicKey theirSignedPreKey = supportsV3 ? preKey.getSignedPreKey() : preKey.getPreKey();
ECPublicKey test = preKey.getPreKey(); // TODO: cleanup
May <ECPublicKey> theirOneTimePreKey = (test == null) ? May <ECPublicKey> .NoValue : new May <ECPublicKey>(test);
May <uint> theirOneTimePreKeyId = theirOneTimePreKey.HasValue ? new May <uint>(preKey.getPreKeyId()) :
May <uint> .NoValue;
AliceAxolotlParameters.Builder parameters = AliceAxolotlParameters.newBuilder();
parameters.setOurBaseKey(ourBaseKey)
.setOurIdentityKey(identityKeyStore.GetIdentityKeyPair())
.setTheirIdentityKey(preKey.getIdentityKey())
.setTheirSignedPreKey(theirSignedPreKey)
.setTheirRatchetKey(theirSignedPreKey)
.setTheirOneTimePreKey(supportsV3 ? theirOneTimePreKey : May <ECPublicKey> .NoValue);
if (!sessionRecord.isFresh())
{
sessionRecord.archiveCurrentState();
}
RatchetingSession.initializeSession(sessionRecord.getSessionState(),
supportsV3 ? (uint)3 : 2,
parameters.create());
sessionRecord.getSessionState().setUnacknowledgedPreKeyMessage(theirOneTimePreKeyId, preKey.getSignedPreKeyId(), ourBaseKey.getPublicKey());
sessionRecord.getSessionState().setLocalRegistrationId(identityKeyStore.GetLocalRegistrationId());
sessionRecord.getSessionState().setRemoteRegistrationId(preKey.getRegistrationId());
sessionRecord.getSessionState().setAliceBaseKey(ourBaseKey.getPublicKey().serialize());
sessionStore.StoreSession(remoteAddress, sessionRecord);
identityKeyStore.SaveIdentity(remoteAddress.getName(), preKey.getIdentityKey());
}
}