An efficient approach to group key management in secure multicast

This research proposes an efficient model and the associated algorithm for the group key management in secure multicast. The proposed model and algorithm are focusing on the communication where members of multicast groups join and leave the groups frequently. In this communication environment, it is pointed out that the group key delivery at the leave has more overhead than that at the join. In our model, the group key is constructed using secret values assigned to individual members, based on the difficulty of the discrete logarithm problem. The inverse values of the secret values are also used. Each member keeps the inverse values of the other members except that assigned to itself. When a new member joins a group, the group key is changed by the key server, and the new group key and the inverse values are sent to members by exploiting IP multicast. When a member leaves, the key server only informs remaining members who is leaving. The group key is changed by each of the remaining members using the inverse values. Using this approach, we can reduce computation complexity and communication overhead of the group key generation after a leave.