A lightweight and continuous authentication protocol for VANETs based on PUF and CSI

In vehicular ad-hoc networks (VANETs), vehicles need to continuously communicate with external entities to obtain surrounding road information. However, such information is typically transmitted through public channels, where identity authentication serves as the trust foundation for ensuring communication security. Traditional authentication schemes face challenges including certificate management, key escrow, high communication overhead, and significant latency. Moreover, VANETs communication processes are inherently dynamic and continuous, during which vehicles may be impersonated or hijacked by attackers, making conventional static authentication schemes inadequate. To address these issues, this paper proposes a lightweight continuous authentication scheme based on Physical Unclonable Functions (PUF) and Channel State Information (CSI). The scheme leverages the inherent hardware characteristics of PUF to authenticate vehicles and Road Side Units (RSUs) through Challenge-Response Pair (CRP) verification. Subsequently, it employs CSI to generate dynamic session keys combined with variable functions for continuous authentication. Furthermore, the session keys can be utilized to update registration information and vehicle pseudonyms, thereby protecting vehicle identity privacy. Security analysis and experimental results demonstrate that the proposed scheme achieves continuous authentication while effectively reducing computational and communication overhead.