private void writeObject(ObjectOutputStream stream) throws IOException {
if (key.isEngineBased()) {
throw new NotSerializableException("engine-based keys can not be serialized");
}
stream.defaultWriteObject();
stream.writeObject(getEncoded());
}
@Override
public BigInteger getS() {
if (key.isEngineBased()) {
throw new UnsupportedOperationException("private key value S cannot be extracted");
}
return getPrivateKey();
}