Secure Time Synchronization With Submicrosecond Accuracy in Controller Area Networks

Abstract

In this article, we achieve submicrosecond accuracy with an AUTOSAR-compliant time synchronization protocol on CAN-FD. In addition to this, we discover two attacks, double replays and forecasting, on the AUTOSAR CanTSyn standard and design fixes for them. Several simple and efficient algorithms are tested, e.g., weighted learning, windowed, and continuous averaging, in order to determine the correct ratio between participants' clocks with minimal computational and communication overheads. We also point out that, at such a high level of synchronization accuracy, there may be significant differences when using simple or double precision floats for encoding the clock ratio with some of the algorithms. Our approach also exploits the direct memory access subsystem instead of CPU interrupts during protocol executions, which reduces the processor load, making the solution suitable for real-time systems. We evaluate the proposed protocol in a realistic scenario by deploying it on an automotive-grade setup with Infineon Aurix development boards.