Temperature Aware Phase/Frequency Detector-Based RO-PUFs Exploiting Bulk-Controlled Oscillators

Sha Taoa and Elena Dubrovab
School of ICT, KTH Royal Institute of Technology.


Physical unclonable functions (PUFs) are promising hardware security primitives suitable for low-cost cryptographic applications. Ring oscillator (RO) PUF is a well-received silicon PUF solution due to its ease of implementation and entropy evaluation. However, the responses of RO-PUFs are susceptible to environmental changes, in particular, to temperature variations. Additionally, a conventional RO-PUF implementation is usually more power-hungry than other PUF alternatives. This paper explores circuit-level techniques to design low-power RO-PUFs with enhanced thermal stability. We introduce a power-efficient approach based on a phase/frequency detector (PFD) to perform pairwise comparisons of ROs. We also propose a temperature compensated bulk-controlled oscillator (BCO) and investigate its feasibility and usage in PFD-based RO-PUFs. Evaluation results demonstrate that the proposed techniques can effectively reduce the thermally induced errors in PUF responses while imposing a low power overhead. The PFD-based BCO-PUF is one of the best among existing RO-PUFs in terms of power efficiency.

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