anchor.diff:  	T2 = crypto:hmac(sha256, K, <<T1/binary, S/binary, P>>),
   	prf(K, S, N, P + 1, T2, [T2 | Acc]).
   
  +-spec autn(SQN, AK, AMF, MAC) -> AUTN
  +        when
  +                SQN :: integer(),
  +                AK :: integer(),
  +                AMF :: binary(),
  +                MAC :: binary(),
  +                AUTN :: binary().
  +%% @doc Network Authentication Token (AUTN).
  +%%
  +%% @private
  +autn(SQN, AK, AMF, MAC)
  +                when is_integer(SQN), is_integer(AK),
  +                byte_size(AMF) =:= 2, byte_size(MAC) =:= 8 ->
  +        SQNa = SQN bxor AK,
  +        <<SQNa:48, AMF/binary, MAC/binary>>.
  +
  
positive.code: 		S :: binary(),
  		N :: pos_integer(),
  		MK :: binary().
  %% @doc Pseudo-Random Number Function (PRF).
  %%
  %%      See RFC5448 3.4.
  %% @private
  
negative.code: 	NasId = atom_to_list(node()),
  	[{nas_id, NasId}, {socket, Socket}, {radius_client, RadIP} | Config];
  init_per_testcase(TestCase, Config)
  		when TestCase == eap_identity_radius_trusted; TestCase == eap_radius_response ->
  	{ok, RadiusConfig} = application:get_env(ocs, radius),
  	{auth, [{RadIP, _, _} | _]} = lists:keyfind(auth, 1, RadiusConfig),
  	{ok, Socket} = gen_udp:open(0, [{active, false}, inet, {ip, RadIP}, binary]),
  