The Arm Triple Core Lock-Step (TCLS) architecture is the natural evolution of Arm Cortex-R Dual Core Lock-Step (DCLS) processors to increase dependability, predictability, and availability in safety-critical and ultra-reliable applications. TCLS is simple, scalable, and easy to deploy in applications where Arm DCLS processors are widely used (e.g., automotive), as well as in new sectors where the presence of Arm technology is incipient (e.g., enterprise) or almost non-existent (e.g., space). Specifically in space, COTS Arm processors provide optimal power-to-performance, extensibility, evolvability, software availability, and ease of use, especially in comparison with the decades old rad-hard computing solutions that are still in use. This article discusses the fundamentals of an Arm Cortex-R5 based TCLS processor, providing key functioning and implementation details. The article shows that the TCLS architecture keeps the use of rad-hard technology to a minimum, namely, using rad-hard by design standard cell libraries only to protect the critical parts that account for less than 4% of the entire TCLS solution. Moreover, when exposure to radiation is relatively low, such as in terrestrial applications or even satellites operating in Low Earth Orbits (LEO), the system could be implemented entirely using commercial cell libraries, relying on the radiation mitigation methods implemented on the TCLS to cope with sporadic soft errors in its critical parts. The TCLS solution allows thus to significantly reduce chip manufacturing costs and keep pace with advances in low power consumption and high density integration by leveraging commercial semiconductor processes, while matching the reliability levels and improving availability that can be achieved using extremely expensive rad-hard semiconductor processes. Finally, the article describes a TRL4 proof-of-concept TCLS-based System-on-Chip (SoC) that has been prototyped and tested to power the computer on-board an Airbus Defence and Space telecom satellite. When compared to the currently used processor solution by Airbus, the TCLS-based SoC results in a more than 5× performance increase and cuts power consumption by more than half.
International audienceSelf-timed Ring based True Random Generators (STRNGs) extract randomness from the jitter of events evenly propagating in a Self-Timed Ring (STR) oscillator. Security of such generators is primarily based on an entropy assessment: an accurate model of the minimum entropy per output bit with physical measurement of the noise source. This assessment is reinforced with both entropy source monitoring and online testing of the output bits. This paper addresses the security of the STRNG. First we identify potential vulnerabilities on the generator and define a threat model. Based on this threat model, we analyze the effect of active attacks in analog simulations (in a 55 nm technology), and by emulating them in a high-level simulation model. Then, we propose simple and efficient countermeasures to thwart attacks focusing on the generator. Finally, we evaluate the output sequences before and after attacks to validate the proposed countermeasures
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