For VW, that was easy because the test setup was known and very rigid.<p>If you randomly check, say, power usage and latency of the on-board RNG (ideally combined with high-resolution IR recordings of the CPU), it will, at least, be harder for the CPU manufacturer to install a backdoored RNG that is active most of the time (but one that only gets activated after receiving some trigger, say a specific instruction sequence would still be virtually undetectable)