A Hardware Based Solution for Freshness of Secure Onboard Communication in Vehicles

Information Technology has become eminent in the development of modern cars. More than 50 Electronic Control Units (ECUs) realize vehicular functions in hardware and software, ranging from engine control and infotainment to future autonomous driving systems. Not only the connections to the outside world pose new threats, also the in-vehicle communication between ECUs, realized with bus systems like CAN, needs to be protected against manipulation and replay of messages. Multiple countermeasures were presented in the past making use of Message Authentication Codes and specific values to provide message freshness, most prominently AUTOSAR’s Secure Onboard Communication (SecOC). However, the currently considered solutions exhibit deficiencies which are hard if not impossible to overcome within the scope of the respective approaches. In this paper we present a new, hardware-based approach that avoids these deficiencies and formally prove its freshness properties.