PUF Secret Recovery Using Intrinsic Confidence Levels

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Solution Overview

Problem

Existing physical unclonable functions (PUFs) lack secure methods for recovering secrets due to reliance on external information, making them vulnerable to attacks.

Innovation Solution

Incorporating intrinsic information about confidence levels in comparison values to simplify the recovery process by solving a hard mathematical problem like Learning with Errors (LWE), which is difficult for external attackers to solve without internal information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional error correction codes are used for secret recovery in PUFs, then error correction capability is provided, but security is weakened due to reliance on external information

Engineering Contradiction:

Improvesecret recovery securityVSAvoidinformation dependency

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The PUF system uses its own intrinsic confidence level information to correct errors during secret recovery, rather than relying on external error correction codes. The confidence levels generated during PUF operation are directly utilized to identify and correct bit errors in the recovered secret, making the system self-sufficient and more secure.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If confidence level information is utilized for error correction, then secret recovery accuracy is improved, but the system requires additional processing circuitry

Engineering Contradiction:

Improvebit stream accuracyVSAvoidprocessing circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The existing PUF circuitry that generates confidence levels during normal operation is made to serve a dual purpose: both characterizing the PUF response quality and enabling error correction during secret recovery. No separate error correction hardware is needed because the confidence level generation logic is reused for error identification and correction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If intrinsic confidence level information is used instead of external information, then security is enhanced, but the recovery process becomes more complex

Engineering Contradiction:

ImprovePUF securityVSAvoidrecovery process simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Confidence level information is generated and stored during the PUF enrollment phase before any secret recovery operations. This preliminary generation of confidence data allows the recovery process to simply retrieve and use this pre-computed information, maintaining simplicity while enhancing security through intrinsic information usage.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11804971B2Correcting physical unclonable function errors based on short integers solutions to lattice problems

Publication Date: 2023.10.31 ANALOG DEVICES INC

AI summary

Physical unclonable functions (PUFs) are described. The PUFs utilize intrinsic information to determine the confidence level of comparison values. The information about confidence levels may be used to simplify the process of recovering the PUF secret. Since the information about confidence levels may be intrinsic, and not know outside the PUF, the PUF may be secure.