Impact of temporal variations on the performance and reliability of configurable ring oscillator PUF

Abstract

Physical Unclonable Functions (PUF) offer promising solution to security problems. A PUF is a die-specific random probabilistic function that is unique for every instance of the die. PUFs derive their randomness from the uncontrolled random manufacturing process variations in the IC. Apart from spatial variation or process variation, ICs are affected by temporal variation. In this work, we study the effects of aging, temperature, and voltage variation on configurable Ring Oscillator (RO) PUF. It is observed that the uniqueness of the ROPUF is not affected to a great extent, where the inter-chip HD is found to be 45.9% which is closer to the ideal value of 50%. The intra-chip HD of PUF degrades with aging with a value ranging between 2.34%–4.21%, so the reproducibility is 96.7%. Also, the ROs are found to be sensitive to temperature and voltage variations. Bit flips occur due to temperature and voltage variations but only when the frequency difference in the RO comparison pair is 1.5 MHz for temperature variation and 1 MHz for voltage variation.