Efficient Group Rekeying Using Application-Layer Multicast

In secure group communications, there are both rekey and data traffic. The authors proposed to use application-layer multicast to support concurrent rekey and data transport. Rekey traffic is bursty and requires fast delivery. It is desired to reduce rekey bandwidth overhead as much as possible since it competes for bandwidth with data traffic. Towards this goal, a multicast scheme that exploits proximity in the underlying network was proposed. The authors further proposed a rekey message splitting scheme to significantly reduce rekey bandwidth overhead at each user access link and network link. Correctness properties for the multicast scheme and rekey message splitting scheme was formulated and proved. The authors have conducted extensive simulations to evaluate the approach. The simulation results show that the approach can reduce rekey bandwidth overhead from several thousand encrypted new keys (encryptions, in short) to less than ten encryptions for more than 90% of users in a group of 1024 users