anchor.diff:  all() -> [{group, sha},
             {group, sha256},
             {group, sha512},
  +          {group, rsa},
             rand_bytes
            ].
   
   groups() -> [{sha, [], [hash]},
                {sha256, [], [hash]},
  -             {sha512, [], [hash]}
  +             {sha512, [], [hash]},
  +             {rsa, [], [sign_verify]}
               ].
   
   hash() ->
  
positive.code: rand_bytes(_Config) ->
      10 = byte_size(crypto2:rand_bytes(10)),
      20 = byte_size(crypto2:strong_rand_bytes(20)).
  
negative.code:     hash(Type, Msgs, Digests),
      hash(Type, lists:map(fun iolistify/1, Msgs), Digests),
      hash_increment(Type, Inc, IncrDigest).
  
  sign_verify() ->
       [{doc, "Sign/verify digital signatures"}].
  sign_verify(Config) when is_list(Config) ->
      SignVerify = proplists:get_value(sign_verify, Config),
      lists:foreach(fun do_sign_verify/1, SignVerify).
  
  %%-------------------------------------------------------------------
  %init_per_suite(Config) ->
  