A Scalable and Reliable Key Distribution Protocol for Multicast Group Rekeying

Scalable group rekeying is one of the important problems that needs to be addressed in order to support secure 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 to reduce the overhead and increase the reliability of the key delivery protocol. We have evaluated the performance of our approach using detailed simulations. Our results show that for most network loss scenarios, the bandwidth used by our protocol is lower than that of previously proposed key delivery protocols.