Optimizing Pseudonym Updation in Vehicular Ad-Hoc Networks

A vehicle can be tracked by monitoring the messages broadcast from it. The broadcast by a source contains its current identity and also allows estimation of its location by receivers. This mapping between the physical entity and the estimated location through the communication broadcast is a threat to privacy. A vehicle can preserve its anonymity by being indistinguishable in the neighborhood crowd through continual change of identity and by hiding among its neighbors. This paper addresses the challenges in providing anonymity to a moving vehicle that uses a temporary identity for transmission and continually changes this pseudonym. As a vehicle moves on a road, its neighbors change in accordance to its relative speed with neighboring vehicles. The nature and size of the neighborhood changes the effective crowd provided by the vehicles constituting this neighborhood. Since, all neighboring vehicles do not contribute to the anonymity; the degree of anonymity is reduced. The work focuses on updation of pseudonym by a vehicle in order to sustain or enhance its anonymity by decorrelating the relation between its physical location and identity. A heuristic that allows a vehicle to switch its pseudonym at a time and place where the anonymity can be enhanced is proposed. Results indicate that updating pseudonyms in accordance to the heuristic enhances the anonymity of a vehicle.