PUF Selector Map for Stable Bit Authentication
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Solution Overview
Problem
Physically unclonable function (PUF) circuits face challenges in maintaining stability over time, leading to potential authentication failures, and the helper data required for error correction can be large and storage-intensive.
Innovation Solution
A selector map is generated to indicate stable and unstable bits in a PUF value, allowing only stable bits to be used for generating a PUF final value, thereby reducing the need for error correction codes and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If helper data in the form of error-correcting codes is used to correct generated PUF values, then the viability of the PUF is maintained over the life of the device, but the helper data may reveal information about the PUF value and may be large creating storage issues
Solution Approach 1:
The patent extracts only the necessary stability information about PUF bits and stores it in a compressed selector map format, rather than storing complete error-correcting codes. This removes the redundant information while preserving the essential function of identifying stable bits for authentication.
Solution Approach 2:
The patent changes the representation of helper data from full error-correcting codes to a binary selector map where each bit indicates whether the corresponding PUF bit is stable. This parameter transformation dramatically reduces storage requirements while maintaining the ability to identify reliable authentication bits.
2Reliability
If helper data is used to compensate for instability in a PUF circuit, then authentication reliability is maintained, but storage requirements increase
Solution Approach 1:
The patent transforms the helper data from full error-correcting codes to a compact binary selector map format. Each bit in the selector map corresponds to a PUF bit and indicates whether it is stable, reducing storage requirements while maintaining authentication reliability through the same stability compensation function.
Solution Approach 2:
The patent segments the helper data into individual bit-level stability indicators within the selector map, allowing only the necessary stability information to be stored and processed, rather than storing complete correction data for all possible errors.
3Productivity
If all PUF bits are used for authentication, then authentication data is maximized, but unstable bits may cause authentication failures
Solution Approach 1:
The patent applies local quality by differentiating between stable and unstable PUF bits through the selector map, and only utilizing the stable bits for authentication. This localized approach ensures that only reliable bits contribute to authentication, preventing failures while maximizing the use of quality bits.
Solution Approach 2:
The patent performs preliminary identification of stable bits using the selector map before authentication occurs. This advance classification allows the system to pre-determine which bits are reliable and will be used for authentication, preventing authentication failures before they occur.
Data Source
AI summary
Approaches for using a physically unclonable function (PUF) are described. A selector map is used to indicate stable and unstable bits in a PUF value that is generated by a PUF circuit. The stable bits of the PUF value generated by the PUF circuit may be selected for use by an application, and the unstable bits ignored.