A Modular Exponentiation Based Batch Rekeying Scheme for Multicast and Broadcast in Mobile WiMAX

Abstract

Mobile WiMAX (IEEE 802.16e) is an emerging wireless technology. It supports wider converge and higher bandwidth than conventional wireless technologies. Multicast and Broadcast (M&B) is a usable service provided by WiMAX. Many applications, such as Pay-TV system, can be more efficiently distributed by using M&B service. Although 802.16e defines M&B Rekeying Algorithm (MBRA) to protect M&B communication, MBRA does not consider forward and backward secrecy. More precisely, the key update procedure is triggered periodically without reflecting group membership change. In this paper, we propose a new modular exponentiation based periodical batch rekeying scheme applicable to WiMAX because MBRA has the property of periodical trigger. Security analysis and performance evaluation show that our scheme is secure and efficient, respectively. Regarding efficiency, our scheme requires O(1) messages to update keys.