CAS-PUF: Current-Mode Array-Type Strong PUF for Secure Computing in Area Constrained SoCs

Secure computing necessitates the integration in Systems-on-Chips (SoCs) of strong Physical Unclonable Functions (PUFs) that can generate a vast amount of Challenge Response Pairs (CRPs) for cryptographic keys generation, identification and authentication. However, the excessive area cost of strong PUF designs imposes integration difficulties to SoCs of area constrained applications, such as the IoT and mobile computing. In this paper, we present a novel strong PUF design, with silicon area requirements significantly lower than those of previous strong PUFs. The proposed Current-mode Array-type Strong PUF (CAS-PUF) is based on a current source topology of only six minimum size transistors, which is tolerant to power supply variation for enhanced reliability. Compared to previous strong PUFs, the CAS-PUF achieves the same number of CRPs with 20% to 72% less area size; while for the same area size, it provides 19 to 53 orders of magnitude higher number of CRPs. Furthermore, extensive Monte Carlo simulations on CAS-PDF show a reliability of 96.45% under ±10% power supply fluctuation; and 97.69% under temperature variation (0°C to 80°C), with an average uniqueness and uniformity of 50.01% and 49.54%, respectively. Therefore, CAS-PUF can be used as a hardware root of trust mechanism to secure computing in area constrained SoCs.