A Centralized Key Table based Communication Efficient Group Key Management Protocol

Group key management is an integral part of secure multicast. Minimizing the number of rekeying messages, maintaining the forward and backward secrecy has always been a challenging task. Though there are many solutions which reduce the rekeying messages from O(n) to O(log2n), they increase with the increase in group size. In this paper, we present a centralized key table based communication efficient group key management protocol in which number of rekeying messages is independent of the group size. In this protocol key management server (KMS) divides a group of n members into n subgroups of size n−1 and maintains a table of n subkeys along with member ID and one group key. Each member has n−1 subkeys, which is a subset of n subkeys of KMS and one group key. The proposed protocol requires only one multicast rekeying message per joining of a new member as well as per eviction of any existing member. As the number of rekeying messages is not dependent on group size, it requires less computation. Index Terms—Group key management, rekeying, subkeys, secure multicast, forward and backward secrecy.