Authentication in very large ad hoc networks using randomized groups

Mobile ad hoc networks (MANETs) are self-organized networks that do not rely in their operation on wired infrastructure. As in any networking technology, security is an essential element in MANET as well for proliferation of this type of networks. But supporting secure communication in MANETs proved to be a significant challenge, mainly due to the fact that the set of nodes in the network can frequently and rapidly change and due to the lack of access to the wired infrastructure. In particular, the trust model and the authentication protocols, which were developed for wired and infrastructure-based networks, cannot be used in MANETs. In this paper, we address the problem of efficient authentication of mobile users distributed in geographically large networks and we propose a new authentication scheme for this case of MANETs. The proposed scheme exploits randomized groups to efficiently share authentication information among nodes that together implement the function of a distributive certification authority (CA). We evaluate the performance of the proposed randomized groups authentication scheme based on two metrics: the total cost of the scheme's operation and its reliability. As an example of the results and as a reference point, we show that the proposed scheme achieves successful authentication when the random group size is around 10 - 12 nodes, irrespectively of the number of mobile nodes, of the number of CAs, and of the mobility model of the nodes in the network.