anchor.diff:      false.
   
   
  +generate_key_test() ->
  +    decode_key(generate_key()).
  +
   decrypt_test() ->
       Key = <<"cw_0x689RpI-jtRR7oE8h_eQsKImvJapLeSbXpwF4e4=">>,
       Token = <<"gAAAAAAdwJ6wAAECAwQFBgcICQoLDA0ODy021cpGVWKZ_eEwCGM4BLLF_5CV9dOPmrhuVUPgJobwOz7JcbmrR64jVmpU4IwqDA==">>,
  
positive.code:             valid
      end,
      PaddedPlaintext = crypto:block_decrypt(aes_cbc128, EncryptionKey, IV, Ciphertext),
      io:format("Padded plaintext: ~w~n", [PaddedPlaintext]),
      pkcs7:unpad(PaddedPlaintext).
  
  encrypt(Plaintext, Key) ->
  
negative.code: encrypt(Plaintext, Key, IV, Timestamp) ->
      {SigningKey, EncryptionKey} = decode_key(Key),
      PaddedPlaintext = pkcs7:pad(Plaintext),
      Ciphertext = crypto:block_encrypt(aes_cbc128, EncryptionKey, IV, PaddedPlaintext),
      Message = encode_message(Timestamp, IV, Ciphertext),
      HMAC = hmac_sha256(SigningKey, Message),
  