ARO-PUF: An aging-resistant ring oscillator PUF design

Physically Unclonable Functions (PUFs) have emerged as a security block with the potential to generate chip-specific identifiers and cryptographic keys. However it has been shown that the stability of these identifiers and keys is heavily impacted by aging and environmental variations. Previous techniques have mostly focused on improving PUF robustness against supply noise and temperature but aging has been largely neglected. In this paper, we propose a new aging resistant design for the popular ring-oscillator (RO)-PUF. Simulation results demonstrate that our aging resistant RO-PUF (called ARO-PUF) can produce unique, random, and more reliable keys. Only 7.7% bits get flipped on average over 10 years operation period for an ARO-PUF due to aging where the value is 32% for a conventional RO-PUF. The ARO-PUF shows an average interchip HD of 49.67% (close to ideal value 50%) and better than the conventional RO-PUF (~45%). With lower error, ARO-PUF offers ~ 24X area reduction for a 128-bit key because of reduced ECC complexity and smaller PUF footprint.