def group_encrypt(self, groupid, message):
        """
        :param groupid:
        :type groupid: str
        :param message:
        :type message: bytes
        :return:
        :rtype:
        """
        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())