Privacy-Preserving Aggregation-Authentication Scheme for Safety Warning System in Fog-Cloud Based VANET

As cities become smarter, the importance of vehicular ad hoc networks (VANETs) will be increasingly pronounced. To support latency- and time-sensitive applications, there have been attempts to utilize fog-cloud computing in VANETs. There are, however, a number of limitations in existing fog-cloud based VANET deployments, ranging from computation and communication bottlenecks to privacy leakage to costly certificate/ pseudonym management to key escrow, and so on. Therefore, in this paper we propose a privacy-preserving aggregation authentication scheme (PPAAS). The scheme is designed for deployment in a safety warning system for fog-cloud based VANETs. Specifically, the PPAAS scheme is realized using a novel efficient anonymous certificateless aggregation signcryption scheme (CASS) proposed in this paper, and allows a fog node to aggregate signcrypted traffic-related messages from surrounding vehicles into an aggregated ciphertext and unsigncrypt them in a batch. We then evaluate the security of PPAAS and demonstrate that it supports confidentiality, authentication, and (efficient) conditional privacy, and key escrow freeness. In particular, our scheme is the first in the literature to achieve efficient conditional privacy, which avoids the need for costly pseudonym management. We also demonstrate that the scheme is practical, based on our simulation results.