Circuit-level techniques for reliable Physically Uncloneable Functions

In this paper we study the effect of transistor supply voltage and body bias on the performance of ring oscillator Physically Uncloneable Functions (PUFs). The uniqueness (ability to identify a PUF) and reproducibility (ability to reproduce the same output) of PUFs increase drastically in the subthreshold region of operation. Also, the reproducibility of PUFs increase when the transistors are forward body biased. A ring oscillator PUF was tested and it achieved a uniqueness of 47.8% and reproducibility of 100% when operating at a supply voltage of 0.2 V. Compared to a base line configuration, our method improved the uniqueness by 18% and reproducibility by 7%. Therefore, apart from architectural optimizations, circuit level considerations like supply voltage and body bias can improve the reliability of PUFs.