Privacy-preserving route reporting scheme for traffic management in VANETs

With the large increase in the number of registered vehicles, the congestion and slow traffic problems are expected to worsen. Vehicular Ad Hoc Networks (VANETs) can play a great role in avoiding these problems by sending guidance to vehicles to pursue alternative routes. However, the published schemes require vehicles to report their future routes which can seriously violate privacy. In this paper, we present privacy-preserving route reporting scheme that suits VANET-enabled traffic management rather than warning vehicles after congestion happens. Vehicles provide encrypted segment-based route information to road side units (RSUs). Instead of sending one message for each route segment, all the segments' data can be collected by one message using homomorphic encryption. RSUs compute the encryption of the expected number of vehicles in each segment of the road without knowing the actual routes of vehicles. Each RSU shares the vehicles' routes information with a traffic management center (TMC), which decrypts the expected total number of vehicles at different segments of the road without knowing the individual vehicles' routes. Then, it conducts analysis and sends predictions and recommendations back to the RSUs. Passing vehicles solicit hints from RSUs on the expected traffic condition in order to decide to take an alternating route if there is a potential of congestion or slow traffic in its main route. Our analysis and evaluation results demonstrate that our scheme can preserve the privacy of the drivers' future routes in an efficient and secure way.