Key agreement and management scheme based on blockchain for 5G-enabled vehicular networks

5G technology has endowed mobile communication terminals with features such as ultrawideband access, low latency, and high reliability transmission, which can complete the network access and interconnection of a large number of devices, thus realizing richer application scenarios and constructing 5G-enabled vehicular networks. However, due to the vulnerability of wireless communication, vehicle privacy and communication security have become the key problems to be solved in vehicular networks. Moreover, the large-scale communication in the vehicular networks also makes the higher communication efficiency an inevitable requirement. In order to achieve efficient and secure communication while protecting vehicle privacy, this paper proposes a lightweight key agreement and key update scheme for 5G vehicular networks based on blockchain. Firstly, the key agreement is accomplished using certificateless public key cryptography, and based on the aggregate signature and the cooperation between the vehicle and the trusted authority, an efficient key updating method is proposed, which reduces the overhead and protects the privacy of the vehicle while ensuring the communication security. Secondly, by introducing blockchain and using smart contracts to load the vehicle public key table for key management, this meets the requirements of vehicle traceability and can dynamically track and revoke misbehaving vehicles. Finally, the formal security proof under the eck security model and the informal security analysis is conducted, it turns out that our scheme is more secure than other authentication schemes in the vehicular networks. Performance analysis shows that our scheme has lower overhead than existing schemes in terms of communication and computation.