AES（advanced encryption standard） is famous for the features of its security

wide application area and easy implemention.It must be light-weight processed if applying to radio frequncy identification（RFID） because RFID tag only uses light-weight encryption algorithm for its resource-limited characteristic.In this paper

the availability was enhanced by an optimal design of AES and using composite structure.The simulation experiments show that it meets the requirements of the small-area and low-power integrated circuit in RFID tag system

higher speed under the same condition

and the composite indicator such as chip area and the response time reaches optimization if the encryption function could be implemented in the tag.The scheme also applies to sensor networks and the other resource-limited environments.