anchor.diff:  
   prop_onetime_auth_verify_correct() ->
       ?FORALL({Msg, Key},
  -            {binary(),
  +            {g_iodata(),
                fault_rate(1, 40, secret_key())},
         ?FORALL(Authenticator, ot_authenticator(Msg, Key),
  -        case secret_key_valid(Key) andalso ot_authenticator_valid(Authenticator) of
  +        case v_iodata(Msg) andalso secret_key_valid(Key) andalso ot_authenticator_valid(Authenticator) of
             true ->
               case Authenticator of
                 {valid, A} ->
  
positive.code: %% CRYPTO ONETIME AUTH
  prop_onetimeauth_correct() ->
      ?FORALL({Msg, Key},
              {binary(),
               fault_rate(1, 40, secret_key())},
         case secret_key_valid(Key) of
           true ->
             Authenticator = enacl:onetime_auth(Msg, Key),
             equals(Authenticator, enacl:onetime_auth(Msg, Key));
  
negative.code: %% CRYPTO AUTH
  prop_auth_correct() ->
      ?FORALL({Msg, Key},
              {g_iodata(),
               fault_rate(1, 40, secret_key())},
         case v_iodata(Msg) andalso secret_key_valid(Key) of
           true ->
             Authenticator = enacl:auth(Msg, Key),
             equals(Authenticator, enacl:auth(Msg, Key));
  