IEC-61508 SIL 3 Compliant Pseudo-Random Number Generators for Probabilistic Timing Analysis

Probabilistic Timing Analysis (PTA), especially its measurement based variant (MBPTA), has shown to be competitive with state-of-the-art timing analysis techniques. The use of MBPTA to analyse the timing behaviour of safety-critical systems rests on its ability to derive trustworthy WCET bounds. This ability depends on the soundness of the MBPTA method per se, as well as on the satisfaction of safety requirements placed on the pseudo-random number generator (prng) that plays a key role in the platform-level randomisation needed by MBPTA. This paper presents the design of a low-area, low-power prng that meets IEC-61508 SIL 3 safety requirements and allows for seamless integration in a real-world multicore architecture. This work enables the development and the IEC-61508 certification of mixed-criticality systems that use MBPTA for deriving timing bounds for mixed-criticality software programs running on multicore processors.