On the Security of a Privacy-Preserving Key Management Scheme for Location Based Services in VANETs

Location based services (LBSs) are promising value-added services in vehicular ad hoc networks (VANETs), which can yield substantial economic profits. To extensively deploy LBSs in VANETs, it is essential to establish an efficient privacy-preserving key management scheme. In this paper, we point out a privacy weakness in a recent key management scheme based on group signatures for LBSs in VANETs; then we propose a secure and privacy-enhanced version. In our scheme, roadside units (RSUs) act as group managers. Vehicles are distributed into groups maintained by these RSUs. If a vehicle’s member key is compromised, one just needs to update the group public key corresponding to its group manager. With this method, the member revocation and privacy leakage problems in schemes based on group signatures are solved effectively. As a result, a vehicle may enjoy LBSs efficiently without surrendering its privacy.