code: def group_encrypt(self, groupid, message):
          
          logger.debug("group_encrypt(groupid=%s, message=%s)" % (groupid, message))
          group_cipher = self._get_group_cipher(groupid, self._username)
          return group_cipher.encrypt(message + self._generate_random_padding())
docs: :param groupid:
          :type groupid: str
          :param message:
          :type message: bytes
          :return:
          :rtype: