An Aging-Resistant RO-PUF for Reliable Key Generation

Physical unclonable functions (PUFs) have emerged as a promising security primitive for low-cost authentication and cryptographic key generation. However, PUF stability with respect to temporal variations still limits its utility and widespread acceptance. Previous techniques in the literature have focused on improving PUF robustness against voltage and temperature variations, but the issues associated with aging have been largely neglected. In this paper, we address aging in the popular ring oscillator (RO)-PUF. We propose a new aging-resistant design that reduces sensitivity to negative-bias temperature instability and hot-carrier injection stresses. Simulation results demonstrate that our aging-resistant RO-PUF (ARO-PUF) can produce unique, random, and more reliable keys. On an average, only 3.8% bits of an ARO-PUF flip over a ten-year operational period because of aging, compared with a 12.8% bit flip for a conventional RO-PUF. The proposed ARO-PUF allows us to eliminate the need for error correction by adding extra ROs. The result shows that an ARO-PUF saves _~ 32x area overhead compared with a conventional RO-PUF with required error correction schemes for a reliable key.