FPGA PUF using programmable delay lines

This paper proposes a novel approach for efficient implementation of a real-valued arbiter-based physical unclon-able function (PUF) on FPGA. We introduce a high resolution programmable delay logic (PDL) implemented by lookup table (LUT) internal structure. Using the PDL, we perform fine tuning to cancel out delay skews caused by asymmetries in routing and systematic variations. We devise a symmetric switch structure that can be easily implemented on FPGA. To mitigate the arbiter metastability problem, we present and analyze methods for majority voting of responses. Lastly, a method to classify and group challenges into different robustness sets is introduced, to further increase the corresponding responses' stability in the face of environmental variations. Experimental evaluations show that the responses to robust challenges have an average error rate of less than 2% under temperature variations from -10°C to 75°C.