Security and authentication are an important guarantee for vehicle to everything (V2X). At present, V2X security schemes in most countries are based on public key infrastructure (PKI). These schemes require additional digital signatures when sending basic safety messages (BSMs), which means security requires additional overhead. Consequently, V2X communication efficiency will be affected in the case of traffic congestion. To solve this problem, we propose a physical-layer authentication model based on channel characteristics in the V2X environment. The model uses the Sage-Husa adaptive Kalman filter, which can dynamically adjust statistical properties of the noises according to observation. Furthermore, we select CSI and RSSI to design a physical-layer authentication scheme based on this model, which can replace the digital signature. Finally, we analyze the impact of the filter algorithm and the factors affecting the authentication threshold, and compare our work with similar schemes. As a result, the proposed scheme makes minor changes to the PKI-based V2X security and effectively reduces the overhead of security. Due to the time-varying channel characteristics, this scheme can prevent impersonation by malicious attackers, thereby improving the security of communication.

安全性和身份验证是车辆通向一切（V2X）的重要保证。当前，大多数国家/地区的V2X安全方案均基于公钥基础结构（PKI）。这些方案在发送基本安全消息（BSM）时需要附加的数字签名，这意味着安全性需要附加的开销。因此，在流量拥塞的情况下，V2X通信效率将受到影响。为了解决这个问题，我们提出了一个基于V2X环境中通道特征的物理层认证模型。该模型使用Sage-Husa自适应卡尔曼滤波器，该滤波器可以根据观察结果动态调整噪声的统计特性。此外，我们选择CSI和RSSI来设计基于该模型的物理层身份验证方案，该方案可以替代数字签名。最后，我们分析了过滤算法的影响以及影响认证阈值的因素，并将我们的工作与类似方案进行了比较。结果，提出的方案对基于PKI的V2X安全性进行了较小的更改，并有效地降低了安全性开销。由于信道的时变特性，该方案可以防止恶意攻击者的模仿，从而提高了通信的安全性。