Lightweight and scalable secure communication in VANET

To avoid a message to be tempered and forged in vehicular ad hoc network (VANET), the digital signature method is adopted by IEEE1609.2. However, the costs of the method are excessively high for large-scale networks. The paper efficiently copes with the issue with a secure communication framework by introducing some lightweight cryptography primitives. In our framework, point-to-point and broadcast communications for vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) are studied, mainly based on symmetric cryptography. A new issue incurred is symmetric key management. Thus, we develop key distribution and agreement protocols for two-party key and group key under different environments, whether a road side unit (RSU) is deployed or not. The analysis shows that our protocols provide confidentiality, authentication, perfect forward secrecy, forward secrecy and backward secrecy. The proposed group key agreement protocol especially solves the key leak problem caused by members joining or leaving in existing key agreement protocols. Due to aggregated signature and substitution of XOR for point addition, the average computation and communication costs do not significantly increase with the increase in the number of vehicles; hence, our framework provides good scalability.