On optimal batch rekeying for secure group communications in wireless networks

Advances in wireless communications and 5 mobile computing have led to the emergence of group 6 communications and applications over wireless. In many of 7 these group interactions, new members can join and current 8 members can leave at any time, and existing members 9 must communicate securely to achieve application-specific 10 missions or network-specific functionality. Since wireless 11 networks are resource-constrained, a key challenge is to pro12 vide secure and efficient group communication mechanisms 13 that satisfy application requirements while minimizing 14 communications costs. Instead of individual rekeying, 15 i.e., performing a rekey operation right after each join or 16 leave request, periodic batch rekeying has been proposed 17 to alleviate rekeying overhead in resource-constrained 18 wireless networks. In this paper, we propose an analytical 19 model to address the issue of how often batch rekeying 20 should be performed. We propose threshold-based batch 21 rekeying schemes and demonstrate that an optimal rekey 22 interval exists for each scheme. We further compare these 23 schemes to identify the best scheme that can minimize the 24 communications cost of rekeying while satisfying appli25 cation requirements when given a set of parameter values 26 characterizing the operational and environmental conditions 27 of the system. In a highly dynamic wireless environment in 28 which the system parameter values change at runtime, our 29 work may be used to adapt the rekeying interval accordingly. 30 J.-H. Cho ( ) · I.-R. Chen · M. Eltoweissy Department of Computer Science, Virginia Tech e-mail: [email protected] I.-R. Chen e-mail: [email protected] M. Eltoweissy e-mail: [email protected]