Estimation during Design Phases of Suitable SRAM Cells for PUF Applications Using Separatrix and Mismatch Metrics

TL;DR

This paper introduces metrics based on separatrix and mismatch concepts to estimate reliable SRAM cells during design, aiming to improve PUF stability without complex error correction.

Contribution

It proposes novel metrics for assessing SRAM cell reliability during design, reducing dependence on error correction for PUF applications.

Findings

Metrics effectively predict cell reliability under noise and temperature variations

Metrics can guide design choices to enhance SRAM-PUF stability

Validation shows improved estimation accuracy for reliable cells

Abstract

Physically unclonable functions (PUFs) are used as low-cost cryptographic primitives in device authentication and secret key creation. SRAM-PUFs are well-known as entropy sources; nevertheless, due of non-deterministic noise environment during the power-up process, they are subject to low challenge-response repeatability. The dependability of SRAM-PUFs is usually accomplished by combining complex error correcting codes (ECCs) with fuzzy extractor structures resulting in an increase in power consumption, area, cost, and design complexity. In this study, we established effective metrics on the basis of the separatrix concept and cell mismatch to estimate the percentage of cells that, due to the effect of variability, will tend to the same initial state during power-up. The effects of noise and temperature in cell start-up processes were used to validate the proposed metrics. The presented metrics may be applied at the SRAM-PUF design phases to investigate the impact of different design parameters on the percentage of reliable cells for PUF applications.