Reducing Security Overhead in the Context of Connected Vehicles

Cooperative Intelligent Transport Systems (C- ITS) are very important in our daily lives. They ensure road safety through the exchange of data between vehicles and road side units (RSU). Due to the sensitivity of the exchanged data between different entities, C- ITS systems are vulnerable to cyber attacks, they require high protection. In order to guarantee the integrity and the authentication of the exchanged messages, the European Telecommunications Standards Institute (ETSI), has specified specific procedures to manage certificates and signatures of all sent messages. Each vehicle periodically sends signed CAMs. Then, the integration of the signature and certificate in each transmitted CAM has a considerable impact on the communication channel load and bandwidth. In this study, we propose a new lightweight authentication mechanism which uses the cluster concept to decrease the network overhead. The objective is to reduce the number of signatures and certificates on all exchanged messages. The key idea is that neighbouring vehicles form a cluster to establish a trust relationship with each other, thus removing the need to send signed messages each time. Our method allows for the exchange of lightweight data without certificates or signatures (unsigned CAMs) and therefore verification and signature processes are no longer necessary all the time, which saves processing time and allows for smoother and faster communications.