arXiv:2611.08774 · v1

Gain-Dependent Entropy Characterization of a Zener Avalanche Noise TRNG via Dual NIST Standards: Toward Low-Cost Hardware Entropy for ICS Deployments

首次提交 2026-11-06 06:51

版本更新 2026-11-06 06:51

雷达观测 2026-11-09 10:16

摘要

True random number generators based on Zener avalanche noise offer a low-cost entropy source for industrial control system and IoT edge devices, yet the relationship between amplifier gain, coupling capacitance, and entropy quality remains uncharacterized under current NIST standards. This paper presents a comprehensive entropy assessment of an op-amp-based Zener avalanche noise generator across five gain configurations and two coupling capacitor values, evaluated against the NIST SP 800-22 statistical test suite and the SP~800-90B entropy source assessment using 1.44 billion raw bits per configuration. We identify a three-phase autocorrelation structure, attributed to comparator saturation-recovery dynamics, consistent across all gain settings. A direct-current substitution experiment, replacing the Zener diode with a stable voltage source at the same bias point, reduces switching activity by approximately 97%, confirming that Zener avalanche noise, rather than amplifier self-excitation, is the necessary entropy source. The coupling capacitor is further shown to govern comparator overdrive and entropy quality independent of this source mechanism, with the smaller capacitance improving entropy, throughput, and bias. The combined results identify an optimal gain configuration achieving a perfect statistical test score, NIST-compliant min-entropy, and peak entropy throughput at a bill-of-materials cost under five dollars, offering practical design guidance for low-cost entropy sources in industrial and embedded deployments.