Fast growing communication networks like wireless ad-hoc networks and Internet-of-things (IoT) put forth new challenges in secure communication like eavesdropping and tampering attacks. For such networks, we consider the following important problem: How to establish a shared secret group key among the nodes of a dynamically formed ad-hoc group? There are two major challenges: (a) The nodes are constrained and cannot support expensive public-key operations, especially for large groups and (b) the neighborhood of an ad-hoc node is not determined a-priori and therefore, the node needs to be able to establish a group key with any dynamic sub-set of the nodes. In this work, we describe a novel template based approach to group key establishment wherein our template is a logical shared secret distribution hierarchy built on the ad-hoc nodes prior to deployment. Our template approach ensures that any given ad-hoc node shares a distinct set of secrets with any dynamic group of nodes, regardless of the physical neighborhood, after deployment. We illustrate our approach using two instantiations of symmetric secret distribution protocols namely: sub-set and dual one-way hash chain distributions.
['Bruhadeshwar Bezawada', 'Xiaojiang Liang', 'Alex X. Liu', 'Rui Li']
A template approach to group key establishment in dynamic ad-hoc groups