A Dynamic and Efficient Self-Certified Authenticated Group Key Agreement Protocol for VANET

Authenticated group key agreement (AGKA) protocols protect the security of communications among a group of users. Dutta and Barua proposed a dynamic AGKA protocol, but it fails to the leaving user attacks and the attacks by two malicious users. In this paper, we propose a dynamic AGKA protocol based on the computational Diffie-Hellman problem. The proposed AGKA protocol achieves sound dynamicity and efficiency. With 10 users in a group, the improvements in computation and communication overheads achieve 82.5% and 72.6 %, respectively. Then the proposed AGKA protocol is applied to vehicular ad hoc network (VANET). SC-AGKA, a self-certified authentication and key agreement protocol for VANET is presented. Pseudonyms are employed with care in SC-AGKA to provide conditional privacy. It is suitable for SC-AGKA to protect the vehicular group communications in VANET considering its security strength and efficiency.