def message
      if valid?
        begin
          Encryption.decrypt(key: @secret.encryption_key,
                             ciphertext: encrypted_message,
                             iv: iv)
        rescue OpenSSL::Cipher::CipherError
          raise InvalidToken, "bad decrypt"
        end
      else
        raise InvalidToken, error_messages
      end
    end
def message
      if valid?
        begin
          Encryption.decrypt(key: @secret.encryption_key,
                             ciphertext: encrypted_message,
                             iv: iv)
        rescue OpenSSL::Cipher::CipherError
          raise InvalidToken, "bad decrypt"
        end
      else
        raise InvalidToken, error_messages
      end
    end
Internal: returns the decrypted message in this token

 Raises InvalidToken if it cannot be decrypted or is invalid

 Returns a string containing the original message in plain text