A Periodic Authentication Scheme for Safety/Security Co-Design on CAN Buses

This is the authors' abstract. We don't add key points for this paper.

With an increasing number of interconnected vehicles, it has become easier for an attacker to gain remote access to in-vehicle buses like CAN and, hence, security measures become necessary. However, most existing attempts to secure CAN either modify the hardware, which leads to increased costs, or apply encryption/authentication, which negatively impacts the timing behavior on the bus. In particular, when using authentication, new data (i.e., an authentication tag) is added, resulting in larger payloads. As a consequence, multiple CAN frames need to be sent (instead of only one) for each message, introducing extra delays and potentially leading to deadline misses. To address this problem, we propose a safety/security co-design approach based on combining a technique we call periodically authenticated encryption (PAE) with plausibility checks. The main idea is to not authenticate each and every message transmitted on CAN, but only with a certain configurable frequency. This way, less authentication tags are sent, which reduces the overhead. Plausibility checks are then used to determine whether non-authenticated messages sent in between two authenticated ones have been altered by an attack, e.g., whether the transmitted values exceed a given range or do not match previous ones. We then illustrate the benefits of the proposed approach on two realistic case studies consisting of emergency braking and adaptive cruise control.