A comparative performance analysis of reliable group rekey transport protocols for secure multicast

Scalable group rekeying is one of the important problems that needs to be addressed in order to support secure multicast communications for large and dynamic groups. One of the challenging issues that arises in scalable group rekeying is the problem of delivering the updated keys to the members of the group in a reliable and timely manner. In this paper, we present a new scalable and reliable key distribution protocol for group key management schemes that use logical key hierarchies for scalable group rekeying. Our protocol, called WKA-BKR, is based upon two key ideas, weighted key assignment and batched key retransmission, both of which exploit the special properties of logical key hierarchies and the group rekey transport payload to reduce the bandwidth overhead of the reliable key delivery protocol. Using both analytic modeling and simulation, we investigate the factors that affect the bandwidth overhead of reliable key delivery protocols. We compare the performance of WKA-BKR with that of other rekey transport protocols, including a recently proposed protocol based on proactive FEC. Our results show that for most network loss scenarios, the bandwidth used by WKA-BKR is lower than that of the other protocols.