}
@Override
public Message respond() {
// Extract shared key from the encrypted message;
PrivateKey key = ChatterContext.get(getCk().getA(),
PublicKeyRequest.PRIVATE_KEY);
try {
Cipher elgamal = new ElgamalCipher();
elgamal.init(Cipher.DECRYPT_MODE, key);
elgamal.update(encryptedKey);