VARS: a vehicle ad-hoc network reputation system

Using mobile ad-hoc networks in an automotive environment (VANET) opens a new set of applications, such as the distribution of information about local traffic or road conditions. This can increase traffic safety and improve mobility. One of the main challenges is to forward event related messages in such a way that the information can be trusted by receiving nodes. Authentication does not solve the problem as it does not target the quality of messages. One promising solution might be given by reputation systems. However, conventional centralized trust establishment approaches are not well suited for use within distributed networks such as those envisioned for automotive scenarios. Therefore, we present VARS, a completely distributed approach based on reputation. Our work is based on the following assumptions: cars move at a high average speed; VANETs may become very large, in the order of thousands or even millions of nodes, so that authenticated identities are not feasible; a solution has to be completely decentralized; available bandwidth for communication remains limited, while processing power and memory continue to increase. We introduce major architecture concepts that enable VARS to operate efficiently in the given environment, present the most relevant algorithms and provide some simulation results. First results show that our scheme works in general.