Abstract
Double Arbiter PUFs (DAPUFs) were developed as a variant to XOR PUFs to improve resilience against machine learning attacks. A recent study on DAPUFs of sizes up to 4-1 DAPUFs showed that all examined DAPUFs were vulnerable to machine learning attacks when attackers have access to a large number of challenge-response pairs (CRPs) [1], [10]. In this paper, we implemented the 5-1 DAPUF on field programmable gate arrays (FPGAs), larger than all previously implemented DAPUFs, and carried out performance evaluations of 5-1 DAPUFs on various properties including response randomness, uniqueness, stability, and security vulnerability. Experimental study on 5-1 DAPUFs shows that responses from the same 5-1 DAPUF circuit to different challenges are adequately highly distinguishable from each other while responses generated on different devices to the same challenges are different enough. 5-1 DAPUF also records the highest randomness among all tested sizes of DAPUFs. However, the stability issue is exacerbated in 5-1 DAPUF, a drawback that is also revealed in earlier studies of DAPUFs. Machine learning attack experiments show that 5-1 DAPUF is more resilient than other DAPUFs, but its responses could still be modeled when an attacker is able to accumulate a large number of CRPs.