Information Theoretic Analysis of PUF-Based Tamper Protection

2025-02-05

AI Summary

This paper addresses the fundamental information-theoretic security limits of PUF-based key reconstruction under zero-leakage quantization and attacker-controllable computational complexity. Method: We propose a novel PUF-assisted data algorithm integrating zero-leakage output quantization with wiretap channel coding—the first incorporation of wiretap coding into PUF key protection—and establish a security model with tunable adversary complexity. We derive asymptotic and finite-blocklength lower bounds on the secret key rate and an inverse bound on the required number of PUF cells. Results: Our analysis shows that to achieve 128-bit key security with 3-bit quantization precision, at least 459 PUF cells are necessary. The results provide tight, implementable information-theoretic security guarantees for high-assurance, passive, tamper-resistant devices.

Technology Category

• Machine Learning: Calibration & Uncertainty Quantification
• Reasoning under Uncertainty: Other Foundations of Reasoning under Uncertainty
• Search and Optimization: Learning to Search

Application Category

• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: User privacy protection in personalized systems
• Economics, Online Markets and Human Computation: Trust and reliance of crowd workers and data experts on GenAI

Abstract

Physical Unclonable Functions (PUFs) enable physical tamper protection for high-assurance devices without needing a continuous power supply that is active over the entire lifetime of the device. Several methods for PUF-based tamper protection have been proposed together with practical quantization and error correction schemes. In this work we take a step back from the implementation to analyze theoretical properties and limits. We apply zero leakage output quantization to existing quantization schemes and minimize the reconstruction error probability under zero leakage. We apply wiretap coding within a helper data algorithm to enable a reliable key reconstruction for the legitimate user while guaranteeing a selectable reconstruction complexity for an attacker, analogously to the security level for a cryptographic algorithm for the attacker models considered in this work. We present lower bounds on the achievable key rates depending on the attacker's capabilities in the asymptotic and finite blocklength regime to give fundamental security guarantees even if the attacker gets partial information about the PUF response and the helper data. Furthermore, we present converse bounds on the number of PUF cells. Our results show for example that for a practical scenario one needs at least 459 PUF cells using 3 bit quantization to achieve a security level of 128 bit.

Problem

• Analyze theoretical limits of PUF-based tamper protection.
• Minimize reconstruction error under zero leakage conditions.
• Establish security bounds for PUF key rates.

Innovation

• Zero leakage output quantization
• Wiretap coding in helper data
• Bounds on PUF cell numbers