Security assessment of a time measurement based Arbiter PUF against electromagnetic fault injection and temperature variations

Physically Unclonable Functions (PUFs) have emerged as a promising hardware-based solution for secure key generation and device authentication, leveraging inherent process variations to produce unique Challenge-Response Pairs (CRPs). Among the various architectures, Arbiter PUFs are particularly attractive due to their simplicity and scalability. However, their resilience against physical attacks remains under-explored. This work presents an extended investigation into the impact of pulsed ElectroMagnetic Fault Injection (EMFI) on a Time Measurement-based Arbiter PUF (TIMA-PUF) implemented on an FPGA. The study initially characterizes the vulnerability to single-pulse injections, demonstrating that a precisely tuned pulse can consistently alter the PUF output. The analysis is further expanded to sequential dual-pulse injections, revealing that the fault impact is often mitigated due to the simultaneous increase in propagation delay across competing paths. To address these vulnerabilities, three distinct countermeasures are proposed and detailed: a Token Monitor, a Glitch Monitor, and a novel Response Monitor. Two specific metrics are introduced to quantitatively evaluate the spatial coverage and detection effectiveness of these protections. Experimental results indicate that the proposed countermeasures offer robust spatial detection and high effectiveness while maintaining a low hardware footprint. This is particularly notable for the response monitor, which requires only 27 Look-Up Tables (LUTs). These findings provide a comprehensive framework for enhancing the fault resilience of TIMA-PUF against advanced EMFI threats. Furthermore, we evaluate the resilience of the proposed TIMA-PUF against temperature variations and demonstrate that it incorporates inherent compensation mechanisms that effectively mitigate thermal effects, resulting in a negligible impact on the generated responses.