Efficient rekey interval for minimum cost on secure multicast system using group key

In this paper, we investigate a rekey mechanism for secure multicast group communications and relate the mechanism to the amount of disclosed information from group key exposure. We also combine cost for the disclosed information and cost for group key updates and analyze the optimum rekey interval. Using the results of the analysis in this paper, we can manage secure multicast groups efficiently with the minimal cost on the bases of number of group members, each member´s security level and withdrawal rates.