An anonymous on-demand source routing in MANETs

Due to the unique features of mobile ad hoc networks (MANETs), traditional wired anonymous protocols cannot be directly adopted in MANETs. On the other hand, skillful as they are, existing MANET anonymous routing protocols are often inherited from traditional routing protocols by modifying the content of routing packets of the baseline MANET routing protocols, which causes themselves subjected to certain inherent defects. This paper proposes a novel anonymous on-demand source routing (AODSR) protocol, which is a scalable distributed solution to achieve sender, receiver, and sender-receiver relation anonymity in MANETs. In AODSR, the route discovery process is not controlled by the initiator/target node, but controlled by a series of random residual-hop numbers. This not only eliminates different protocol behaviors between the initiator/target node and intermediate nodes, but also avoids the flooding of routing packets. With the aid of the 'buddy' group strategy, the anonymity is further reinforced. Based on our security analysis, the peculiar reachability attack caused by the broadcast nature of wireless networks and the shielding attack caused by the hidden-terminal problem, which are often ignored by existing anonymous MANET routing protocols, are also countered against by AODSR. Theoretical analysis and simulation shows that AODSR achieves high degree of anonymity while requiring low computational complexity and communication overhead. Copyright (C) 2008 John Wiley & Sons, Ltd.