An Effective Constant-Rounds Group Key Exchange for Dynamic Groups

In this paper, the Authenticated Group Key Exchange (AGKE) schemes for dynamically changing groups are studied. In most of these schemes the network and compute overhead are related to the number of total group members. These schemes are neither scalable nor practical in the group communication environments with large membership. An efficient identity (ID)-based authenticated group key agreement scheme with two-round is proposed. It can reduce the overhead of key agreement when the group membership is changed, because the overhead is only related to the number of joining or leaving members. Furthermore, the message authenticated by signature in the first round is transmitted in unicast way and the message broadcasted in the second round is authenticated by the HMAC operation.