A privacy preserving solution for the protection against sybil attacks in vehicular ad hoc networks

Services provided by vehicular Adhoc Networks (VANETs) would be impaired if faced to sybil attacks, by which malicious vehicles claim multiple identities at the same time. The prevention of these attacks, which could occur in or out of the Road Side Units (RSUs) coverage, is challenging, as it should meet a compromise between the ability to identify the real identity of the malicious vehicle, and prevention of vehicles from being tracked by malicious entities. We propose in this paper a solution to prevent and detect Sybil attacks in VANETs. The identification of attackers is based on two types of authentication techniques. The first uses RFID tags embedded in the vehicle to authenticate them to the RSU and obtain short lifetime certificates. The second uses certificates to authenticate vehicles to their neighbors. The vehicular network we are considering is divided into different zones brought under the control of different certification authorities, forcing a vehicle to change its certificate when moving from a zone to another. One important characteristic of the proposed solution is that it prevents attackers from tracking the mobility of the vehicles. Avoiding false negatives is also addressed using observers (e.g., software components in charge of monitoring) in vehicle nodes. A set of simulation scenarios are conducted to evaluate the performance of the solution.