public MessageKeys getMessageKeys()
{
byte[] inputKeyMaterial = getBaseMaterial(MESSAGE_KEY_SEED);
byte[] keyMaterialBytes = kdf.deriveSecrets(inputKeyMaterial, Encoding.UTF8.GetBytes("WhisperMessageKeys"), DerivedMessageSecrets.SIZE);
DerivedMessageSecrets keyMaterial = new DerivedMessageSecrets(keyMaterialBytes);
return(new MessageKeys(keyMaterial.getCipherKey(), keyMaterial.getMacKey(), keyMaterial.getIv(), index));
}
private static DerivedKeys calculateDerivedKeys(uint sessionVersion, byte[] masterSecret)
{
HKDF kdf = HKDF.createFor(sessionVersion);
byte[] derivedSecretBytes = kdf.deriveSecrets(masterSecret, Encoding.UTF8.GetBytes("WhisperText"), 64);
byte[][] derivedSecrets = ByteUtil.split(derivedSecretBytes, 32, 32);
return(new DerivedKeys(new RootKey(kdf, derivedSecrets[0]),
new ChainKey(kdf, derivedSecrets[1], 0)));
}
public Pair <RootKey, ChainKey> createChain(ECPublicKey theirRatchetKey, ECKeyPair ourRatchetKey)
{
byte[] sharedSecret = Curve.calculateAgreement(theirRatchetKey, ourRatchetKey.getPrivateKey());
byte[] derivedSecretBytes = kdf.deriveSecrets(sharedSecret, key, Encoding.UTF8.GetBytes("WhisperRatchet"), DerivedRootSecrets.SIZE);
DerivedRootSecrets derivedSecrets = new DerivedRootSecrets(derivedSecretBytes);
RootKey newRootKey = new RootKey(kdf, derivedSecrets.getRootKey());
ChainKey newChainKey = new ChainKey(kdf, derivedSecrets.getChainKey(), 0);
return(new Pair <RootKey, ChainKey>(newRootKey, newChainKey));
}