Direct challenge ring oscillator PUF (DC-ROPUF) with novel response selection

Physical unclonable functions (PUFs) have become commercially available for anti-counterfeiting and authentication applications. PUF circuits are built on ASICs but can be implemented on FPGAs. For many electronic products, FPGAs are used in order to shorten development periods and reduce costs. Therefore, implementing PUFs on FPGAs can improve security in nearly all electronic products. However, when implementing PUFs on FPGAs, it is difficult to uniformly arrange logic cells (or logic elements) and maintain uniform wire lengths, which decreases the overall performance of PUFs. In this study, we focused on a ring oscillator PUF (ROPUF) implemented on an FPGA and improved the uniqueness to nearly the ideal value (50%) by using a novel response selection method. Moreover, it is possible to improve the number of challenge response pairs (CRPs) compared to conventional ROPUFs by giving response signals directly to the RO part (DC-ROPUF). As they can be realized by automatic placement and routing without any restriction, high-performance PUFs can be easily implemented on FPGAs.