A RSU-aided distributed trust framework for pseudonym-enabled privacy preservation in VANETs

Vehicular ad hoc networks (VANETs) have the potential to change the way of people drive, travel and so on, in which vehicle can broadcast and forward the message of road condition or emergency. When the received messages are unreliable, they may lead the vehicles to make wrong decisions. To assess how trustworthy the messages are, every vehicle holds the reputation value in the trust-based schemes. In pseudonym-based schemes, vehicles change their pseudonyms by some kind of manner to confuse the trackers. However, the reputation value provides an additional clue to track vehicle when it and the pseudonym change asynchronously. To reconcile the conflict of privacy preservation and reputation evaluation, we propose a distributed trust framework for pseudonym-enabled privacy preservation in VANETs. In this framework, the road side unit assigns the reputation label certificate (RLC) to evaluate the reliability of message for every vehicle in its communication range. To preserve the privacy, the RLC manifests two trust statuses to replace the specific reputation value. All the reputation values of vehicles are stored in the centrical database. To encourage vehicle to follow the rules, the reputation update algorithm is designed with different weights, which achieve the reputation value increasing slowly and decreasing quickly. When RLC of vehicle is revoked, its security and privacy will not be protected. Finally, theoretical analysis and simulations show that our scheme can efficiently meet the requirements of security and privacy in VANETs.