I. Introduction
Vehicle-to-everything (V2X) communication has recently attracted significant attention. V2X involves many entities, such as vehicles equipped with an onboard unit (OBU), infrastructure including base stations and roadside units (RSUs), authorities, and pedestrians. V2X can provide valuable information and services concerning road safety, traffic flow, traveling routes, entertainment, etc., which enhances the driving experience and safety [1]. Vehicles actively contribute to the system by collecting and sending various information from the vicinity, whereas other members help V2X increase the network and data availability and reliability. For instance, if an accident or collision occurs, adjacent vehicles collect and broadcast a message for other vehicles to detour or pass the area with extra caution. They also send their speed and acceleration data in terms of traffic flow in a certain area. In this scenario, the authorities play an important role in issuing certificates to legitimate members, which can authenticate whether the sender is reliable.