Research on Update strategy in batch group re-keying

In order to offer security for multicast applications, the group key has to be changed whenever a user joins or leaves the group. At present, there are two re-keying strategies: individual re-keying and batch re-keying. Individual re-keying method has the problems of inefficient and out-of-sync. Batch re-keying method alleviates these problems, but this method ignores the change probabilities of members. In this paper, we propose the triggered batch re-keying based on the six-probability-optimization key-tree. First, we construct structure of the six-probability-optimization key-tree according to the users' change probabilities. Then set trigger batch re-keying cycle for the group manager. The paper proves that our structure improves scalability of group members and adapts better to the dynamic changes in multicast group membership, and this approach further reduces the overhead of group re-keying and communication costs through performance analysis and simulation experiments.