TOHIP: A topology-hiding multipath routing protocol in mobile ad hoc networks

Existing multipath routing protocols in MANETs ignore the topology-exposure problem. This paper analyzes the threats of topology-exposure and propose a TOpology-HIding multipath Protocol (TOHIP). TOHIP does not allow packets to carry routing information, so the malicious nodes cannot deduce network topology and launch various attacks based on that. The protocol can also establish multiple node-disjoint routes in a route discovery attempt and exclude unreliable routes before transmitting packets. We formally prove that TOHIP is loop-free and does not expose network topology. Security analysis shows that TOHIP can resist various kinds of attacks efficiently and effectively. Simulation results demonstrate that TOHIP has better capability of finding routes and can greatly increase the capability of delivering packets in the scenarios where there are malicious nodes at the cost of low routing overhead. Multipath routing protocols have attracted a lot of attentions recently in MANET for their unique capability in supporting load balancing and improving routing reliability in high dynamic scenarios [1,2]. However, this kind of protocol may become a vulnerable target for the malicious nodes to explore and launch various attacks for the same reason. Therefore, many researchers have designed secure multipath routing protocols [3]. However, as far as we know, none of the existing secure multipath routing protocols deals with the topology-exposure problem. Topology-exposure is a serious problem for MANET, which makes it possible for the malicious nodes to launch many kinds of attacks, such as black hole attack [4], wormhole attack [5], rushing attack [6,7] and sybil attack [8]. Topology-exposure is much more serious in multipath routing protocols than in other routing protocols considering that multipath routing protocols usually carry a lot of routing information in route messages in order to find sufficient routes. In some cases, data packets are also required to carry routing information. For example, Dynamic Routing Protocol (DSR) carries the whole route from source to destination in packet headers [9]. Malicious nodes can deduce part or the whole network topology based on the captured routing information and it is hard to ensure the confidentiality of routing information because of the open media network environment in which any node can capture packets within its transmission range. To deal with the topology-exposure problem, this paper thoroughly analyzes the threats brought by topology-exposure, defines topology-hiding and designs a TOpol-ogy-HIding multipath routing Protocol (TOHIP). TOHIP does not contain link connectivity information in route