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RESP: A robust Physical Unclonable Function retrofitted into embedded SRAM array

Physical Unclonable Functions (PUFs) have emerged as an attractive primitive to address diverse hardware security issues in Integrated Circuits (ICs). A majority of existing PUFs rely on a dedicated circuit structure for generating chip-specific signatures, which often imposes concerns due to area/power overhead and extra design efforts. Furthermore, existing PUF-based signature generation cannot be employed to authenticate chips already in the market. In this paper, we propose RESP, a novel PUF structure realized in embedded SRAM array, a prevalent component in processors and system-on-chips (SOCs), with virtually no design modification. RESP leverages on voltage-depend memory access failures (during write) to produce large volume of high-quality challenge-response pairs. Since many modern ICs integrate SRAM array of varying size with isolated power grid, RESP can be easily retrofitted into these chips. Circuit-level simulation of 1000 chips using realistic process variation model shows high uniqueness of 49.2% average inter-die Hamming distance and good reproducibility of 2.88% intra-die Hamming distance under temperature <; 85°C. The device aging effect, e.g. bias temperature instability (BTI), results in only 4.95% estimated unstable bits for ten-year usage.