anchor.diff:      AesKey = PrivKey,
       Salt = SaltFun(),
       IV = list_to_binary([?i32(EngineBoots), ?i32(EngineTime) | Salt]),
  -    EncData = crypto:block_encrypt(?BLOCK_CIPHER_AES, 
  -				   AesKey, IV, Data),
  +    EncData = crypto:crypto_one_time(?BLOCK_CIPHER_AES, 
  +                                     AesKey, IV, Data, true),
       {ok, binary_to_list(EncData), Salt}.
   
   aes_decrypt(PrivKey, MsgPrivParams, EncData, EngineBoots, EngineTime)
  
positive.code:     %% 7.3.2.3
      Packet2 = patch_packet(binary_to_list(Packet)),
      %% 7.3.2.5
      MAC = binary_to_list(crypto:hmac(sha, AuthKey, Packet2, 12)),
      %% 7.3.2.6
      MAC == AuthParams;
  sha_auth_in(_AuthKey, _AuthParams, _Packet) ->
  
negative.code:     Salt = MsgPrivParams,
      IV = list_to_binary([?i32(EngineBoots), ?i32(EngineTime) | Salt]),
      %% Whatabout errors here???  E.g. not a mulitple of 8!
      Data = binary_to_list(crypto:crypto_one_time(?BLOCK_CIPHER_AES, 
                                                   AesKey, IV, EncData, false)),
      Data2 = snmp_pdus:strip_encrypted_scoped_pdu_data(Data),
      {ok, Data2}.
  
  