Defending against Roadside Attackers

Communication between vehicles is a very promising technology to reduce fatalities and injuries in road traffic. Vehicles spontaneously form communication networks where they exchange messages to warn surrounding vehicles. Theoretically, this system is open to any communication node that is equipped with the required communication technology. This openness demands appropriate security mechanisms in order to protect against attacks and misuse. In this work, we present a mechanism to protect the system against a particular kind of attacker, the socalled roadside attacker. First, we explain the abilities of such an attacker. Then, we introduce a defense mechanism that is based on the fact that the roadside attacker can only move barely compared to a vehicle. The idea is to build up trust relations to vehicles that have been neighbors for a certain time and thus proofed their movement. This property can not be achieved by a roadside attacker. We show how to realize such a mechanism and discuss its limitations. We further show how to integrate such a mechanism into a security system that we refer to as vehicle behavior evaluation framework.