Secure Broadcast with One-Time Signatures in Controller Area Networks

Broadcast authentication in Controller Area Networks CAN is subject to real time constraints that are hard to satisfy by expensive public key primitives. For this purpose the authors study here the use of one-time signatures which can be built on the most computationally efficient one-way functions. The authors use an enhancement of the classical Merkle signature as well as the more recently proposed HORS signature scheme. Notably, these two proposals offer different trade-offs, and they can be efficiently paired with time synchronization to reduce the overhead caused by the re-initialization of the public keys, which would otherwise require expensive authentication trees. The authors do outline clear bounds on the performance of such a solution and provide experimental results on development boards equipped with Freescale S12X, a commonly used automotive grade micro-controller. The authors also benefit from the acceleration offered by the XGATE co-processor available on S12X derivatives which significantly increases the computational performances.