Abstract
Intelligent Transportation System (ITS) is one of the Internet of Things (IoT) systems that can achieve reliable transportation by providing communications between vehicles and infrastructure units. The interaction between them is called Vehicle-to-Everything (V2X) communication that is bridged by LTE-V2X protocol. However, a V2X communication link faces a significant challenge in cyber-security. Road entities and Road Side Units (RSUs) are exposed to various cyber-attacks, including internal and external attacks. Internal attackers have valid credentials; thus, detecting them is still a challenge. As a result, a trust model was suggested by existing work to protect the network against internal attackers. In this paper, a global trust-based model is proposed for securing V2X communications against RSU attacks. Trust decision is made based on two levels: distributed and global levels. Each road entity can make its local decision based on the distributed trust model. Additionally, the central server has the responsibility to make the global decision and reduce the impact of various RSU attacks. Also, multiple experiments are conducted with different percentage of malicious RSUs to measure the performance of the proposed model. Simulation results show that the proposed model achieves lowest Packet Dropping Rate (PDR) values for various number of malicious nodes in comparison with existing models.