Temperature-aware cooperative ring oscillator PUF

Physical unclonable functions leverage the manufacture variations during silicon fabrication process and have found many security related applications. The ring oscillator PUF relies on pairs of ring oscillators which have sufficiently large difference in delay to generate reliable bits. Current RO PUF approaches use redundancy to provide reliability under different operating temperature and thus have very high hardware cost.We propose a temperature-aware cooperative (TAC) RO PUF implementation to reduce such cost. The basic idea is to allow a pair of ring oscillators to generate an unreliable bit as long as we can find means to convert it to a reliable bit. We define bit generation rules that explicitly take temperature into consideration and pair up the ring oscillator pairs so they can cooperate. Experiments on FPGA show that our approach can significantly improve the efficiency of the RO PUF implementation. With the same hardware that the current state-of-art approach requires to generate one reliable bit, our TAC RO PUF approach can generate as high as 1.8 reliable bits, that is, an 80% improvement in hardware utilization.