PUF Key Reconstruction Using Helper-Data Bias Testing
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Solution Overview
Problem
PUFs with high bias can leak information about cryptographic keys through helper data, compromising security, and existing methods for detecting PUF bias introduce additional handling risks that may reveal sensitive information.
Innovation Solution
An electronic cryptographic device with a physically unclonable function (PUF) that generates noisy bit strings, helper data for key reconstruction, and a statistical unit to execute tests using helper data, ensuring secure key generation and PUF health monitoring without leaking information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If helper data is generated from PUF responses with high bias, then key reconstruction reliability is improved, but information about the cryptographic key leaks through the helper data
Solution Approach 1:
The patent introduces an intermediary statistical test that operates on the PUF response data before key generation. This test verifies whether the PUF response exhibits acceptable bias characteristics without requiring external intervention or additional handling of the PUF device itself. The statistical test acts as a mediator that filters out responses with excessive bias, thereby preventing information leakage while maintaining reliability for acceptable responses
Solution Approach 2:
The system performs self-verification by executing the statistical test internally using the PUF's own response data. The PUF device generates the response, immediately tests it against bias criteria, and only proceeds with key generation if the test passes. This self-service approach eliminates the need for external bias detection mechanisms that would require additional handling of sensitive data
2Reliability
If statistical tests are executed on PUF responses to detect bias, then PUF health monitoring is improved, but additional handling risks introduce information leakage
Solution Approach 1:
The statistical test serves as an intermediary layer between the PUF response and any external monitoring systems. Instead of directly examining or transmitting PUF responses for health monitoring, the system uses the statistical test results as an indirect indicator of PUF health. This intermediary approach allows health monitoring without requiring additional handling or exposure of the actual PUF response data
Solution Approach 2:
The patent replaces physical handling and manual inspection methods with automated statistical computation. Instead of mechanically examining PUF responses or manually verifying bias characteristics, the system uses computational statistical tests that automatically evaluate the response data. This substitution reduces the risk of information leakage associated with human handling while maintaining effective health monitoring
Data Source
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AI summary
An electronic cryptographic device (100) arranged to determine a cryptographic key, the cryptographic device comprising a physically unclonable function (PUF) (110) arranged to produce a first noisy bit string (112) during the enrollment phase and a second noisy bit string (114) during the reconstruction phase, a statistical unit (120) arranged to execute a statistical test for verifying correct functioning of the physical unclonable function, the statistical test computing a statistical parameter for the physical unclonable function using helper data, the statistical test determining correct functioning if the statistical parameter satisfies a criterion of the statistical test.