A dynamic anonymous authentication scheme with trusted fog computing in V2G networks

As an important component of smart grid, vehicle-to-grid (V2G) is helpful to improve grid stability, save on generation costs, and reduce energy consumption. However, the existing V2G authentication schemes focus on the trustworthiness of electric vehicles (EVs), instead of the trustworthiness of fog servers (FSs). For unsuspecting EVs, malicious FSs may steal their sensitive data and compromise privacy. We propose a dynamic anonymous authentication scheme with trusted fog computing in V2G networks. In our scheme, to ensure the trustworthiness of the FSs in V2G networks, a collaborative trust evaluation model among FSs is designed. The trust value of FSs can be calculated by comprehensively analyzing the timeliness, authenticity, and execution of FSs' behavior in the collaboration process. Meanwhile, trust evaluation is incorporated into the dynamic anonymous authentication scheme against malicious FSs and ensure a trusted environment of EVs in the authentication process. During the authentication process, to avoid the key escrow and computational overhead of FSs, the certificateless mechanism and aggregated signatures of non-linear pairs are used. We use a combination of long-term anonymity (LID) and temporary anonymity (TID) to ensure the anonymity and the signatures freshness of EVs. Finally, security proofs based on random oracle models and non-formal security analysis show that our scheme satisfies seven security requirements and resists five common attacks. The simulation results show that, in comparison with the five reference schemes, our scheme reduces average computational and communication overheads by 80.05% and 47.68%, respectively.