Pairwise key establishments without key pre-distribution for mobile ad hoc network environment

Because all data packets are transmitted via an unreliable medium in ad hoc networks, it is indispensable to establish a secure pairwise key between any two nodes in the networks. In the key pre-distribution based schemes, because the same pre-distributed keys are spread over a number of nodes in the network, even a small number of compromised nodes can threaten the security of the network. On the other hand, other schemes using a pre-shared key among all nodes are only suitable for static networks and cannot be applied to the mobile network environment. In the proposed scheme, each node establishes some keys with nodes that are at most three hops away at network configuration time. Later, when any two nodes establish a pairwise key between them, all nodes on the route between them contribute to the establishment by sending their own secret keys to both nodes. Here, the pre-established keys are employed to encrypt the secret keys sent from the nodes on the route. The simulation results show that the proposed scheme is better than the key pre-distribution based scheme in terms of the number of exchanged messages, the success frequency of key establishment, and the robustness against compromise of nodes.