Abstract
Computing and communications in wireless ad hoc networks (WAHNs) generally require collaboration among groups of peers. This, in addition to a growing number of group applications over WAHNs, have motivated research in secure group communication services as a means for efficient and secure communications in WAHNs. Key distribution is at the heart of secure group communications. Existing key distribution schemes, designed for infrastructure networks, tend to be inappropriate for the infrastructure-less WAHNs. Also, most of these schemes assume network-level multicast which is difficult to implement in WAHNs. We propose a new efficient and scalable combinatorial key distribution scheme (CKDS) to support secure group communications in WAHNs. CKDS partitions nodes over a virtual Cartesian key space and uses combinatorial exclusion basis systems for key distribution over application-level multicast. We employ a fully distributed unicast key distribution underlying a virtual application-level multicast infrastructure. Two variants of CKDS are proposed, namely, m-dimensional multicast and 2D multicast. Performance analysis shows that these schemes achieve lower network traffic overhead as well as lower computational overhead per node compared to other unicast key distribution schemes in WAHNs. We also show our scheme to be scalable with respect to both computational and storage needs.