anchor.diff:          end).
           
   prop_seal_box_failure_integrity() ->
  -    ?FORALL({Msg, {PK1, SK1}}, {fault_rate(1,40,g_iodata()), fault_rate(1,40,keypair())},
  +    ?FORALL({Msg, {PK1, SK1}}, {z_fault_rate(1,40,g_iodata()), z_fault_rate(1,40,keypair())},
         begin
            case v_iodata(Msg) andalso keypair_valid(PK1, SK1) of
              true ->
  
positive.code: prop_stream_correct() ->
      ?FORALL({Len, Nonce, Key},
              {int(),
               fault_rate(1, 40, nonce()),
               fault_rate(1, 40, secret_key())},
          case Len >= 0 andalso nonce_valid(Nonce) andalso secret_key_valid(Key) of
            true ->
                CipherStream = enacl:stream(Len, Nonce, Key),
  
negative.code: 
  prop_sign() ->
      ?FORALL({Msg, KeyPair},
            {z_fault_rate(1, 40, g_iodata()),
             z_fault_rate(1, 40, sign_keypair())},
        begin
          case v_iodata(Msg) andalso sign_keypair_secret_valid(KeyPair) of
            true ->
  