Logic State Imaging From FA Techniques for Special Applications to One of the Most Powerful Hardware Security Side-Channel Threats

Contactless Fault isolation (CFI) techniques of Microelectronic Debug and Failure Analysis (FA) are developed for the identification of anomalies. If not only anomalies can be detected but also regular logical functionality, the contactless approach opens up a path to hardware security attacks. Logical state information is typically more complicated to detect than anomalies, as the signal level is usually considerably smaller. Successful Logic State Imaging (LSI) has been published in the FA community using specific derivatives of photon emission (PE) and laser-based CFI techniques. This work investigates how the contactless LSI techniques can be used for reading sensitive data out of security-relevant circuitry. The qualification of PE, Thermal Laser Stimulation (TLS), and Laser Logic State Imaging (LLSI) to read out Static Random-Access Memory (SRAM) and battery-backed RAM (BBRAM) cells is demonstrated in two case studies. LLSI offers perspectives for low voltage technologies and feature size resolution by possibly expanding into the visible spectral regime. Therefore, the security risk for some technology generations to come will stay. Furthermore, when considering the use of artificial intelligence, CFI techniques can reach new dimensions of tracking sensitive on-chip data with unimagined consequences for security applications.