anchor.diff:      binary(enacl:auth_size()).
   
   ot_authenticator(Msg, Key) ->
  -  fault(ot_authenticator_bad(), ot_authenticator_good(Msg, Key)).
  +  z_fault(ot_authenticator_bad(), ot_authenticator_good(Msg, Key)).
   
   ot_authenticator_valid({valid, _}) -> true;
   ot_authenticator_valid({invalid, _}) -> true;
  
positive.code:         ]),
          return([]));
  g_iolist(N) ->
      fault(
          oneof([
            elements([a,b,c]),
            real(),
  
negative.code: %% CRYPTO ONETIME AUTH
  prop_onetimeauth_correct() ->
      ?FORALL({Msg, Key},
              {z_fault_rate(1, 40, g_iodata()),
               z_fault_rate(1, 40, secret_key())},
         case v_iodata(Msg) andalso secret_key_valid(Key) of
           true ->
             Authenticator = enacl:onetime_auth(Msg, Key),
  