A pair selection algorithm for robust RO-PUF against environmental variations and aging

Physically 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 propose a reliable pair selection algorithm (RePa) that can generate reliable keys from an RO-PUF under aging, voltage, and temperature variations. The RePa approach selects RO pairs with both initial frequency difference and aging rate/slope in mind. The aging slope is predicted by exploiting correlation that exists between frequency variation with respect to voltage and frequency variation with respect to aging. We evaluate RePa with simulations to show that it achieves significant improvement over the current state of the art in terms of reliability and cost. The proposed approach can achieve ~ 3.0x more robust key with only ~ 2.3x more ROs required than the conventional RO-PUF pair selection for the same key size.