{
  description = "Zentralwerk network secret GPG key";

  outputs = { ... }: {
    lib.gpgKey = null;
    # test key
    lib.dyndnsKey = "Dr1QHSfNtAwgbdoNBtCgl5NxsSXlaw9+qo7juiVTv58=";
    # test credentials
    lib.pppoe.upstream4 = {
      user = "test@example.com";
      password = "secret";
    };
  };
}