In recent years, several attacks have impressively demonstrated that the software running on embedded controllers in cars can be successfully exploited -- often even remotely. The fact that components that were hitherto purely mechanical, such as connections to the brakes, throttle, and steering wheel, have been computerized makes digital exploits life-threatening. Because of the interconnectedness of sensors, controllers and actuators, any compromised controller can impersonate any other controller by mimicking its control messages, thus effectively depriving the driver of his control. The fact that carmakers develop vehicles in evolutionary steps rather than as revolution, has led us to propose a backward-compatible authentication mechanism for the widely used CAN vehicle communication bus. Vatican allows recipients of a message to verify its authenticity via HMACs, while not changing CAN messages for legacy, non-critical components. In addition, VatiCAN detects and prevents attempts to spoof identifiers of critical components. We implemented a VatiCAN prototype and show that it incurs a CAN message latency of less than 4~ms, while giving strong guarantees against non-authentic messages.
. Conference on Cryptographic Hardware and Embedded Systems (CHES)