Trade-Off Analysis of Safety and Security in CAN bus communication

While safety is thoroughly applied to the development of transportation systems, one of the prominent challenges of the last years is the integration with security concepts, required by the ubiquitous connectivity and increased value in data. A joint safety/security design can expose sometimes to trade-offs, since safety and security requirements may not match perfectly or even be incompatible to a certain degree. On the other hand, well-known solutions or best-practices in one field may create new issues in the other. This paper analyses an example of this joint design, that is the combination of integrity with encryption considering the constraints of a typical CAN network and real-time traffic. The analysis is presented considering different attacker models, packet fragmentation issues and the residual probability of error of the combined scheme.