A Novel Technique for Ring Oscillator Based PUFs to Enroll Stable Challenge Response Pairs

Silicon physical unclonable function (PUF) exploits random variations in the manufacturing process to extract unique information for each chip. As one of the most popular techniques to implement a PUF, ring oscillator based PUF (RO-PUF) is easy to implement for both ASIC and FPGA. However, RO-PUF suffers from the lack of reliability caused by temperature and supply voltage variations. In this paper, we proposed a post-processing technique to improve the reliability of RO-PUF. The main idea is that we allow RO-PUF to generate unstable responses as long as we can find means to filter them out during enrollment. Our proposed scheme generates a signal indicating whether the response is stable, and we could filter out unstable challenge response pairs depending on this signal during enrollment. Experimental results showed that the error rate of challenge response pairs enrolled by our proposed scheme was reduced from 19.94% to 0.35% due to voltage variation, and it was reduced from 6.65% to 0.10% due to temperature variation.