An efficient and scalable EBS-based batch rekeying scheme for secure group communications

In a multicasting environment, group communications is essential. An important issue of providing secure group communications is group key management. The exclusion basis system (EBS) provides a framework for supporting group key management, especially in a large-size network. In EBS, a key server (KS) is used to generate both administration and session keys. In turn, KS uses these keys to distribute rekeying message to group members so as to keep them from eavesdropping and taping. However, the EBS system does not allow member nodes to join or leave their group. In this paper, we propose an EBS-based batch rekeying scheme which supports three operations, join, leave with collusion-resistant (L/CR), and leave with collusion-free (L/CF). To provide the join operation, KS periodically performs batch rekeying. Karnaugh map (K-map) is used in operation L/CR while the Chinese Remainder Theorem (CRT) is applied to operation L/CF. Both backward and forward secrecies are guaranteed in the proposed scheme. We compare the performance of the proposed scheme with that of EBS in terms of three performance metrics: storage cost, computation overhead, and communication overhead. By comparison, we notice that the proposed scheme outperforms EBS in all three categories. The simulation results also indicate that the proposed scheme is more efficient and scalable than EBS.