PUF-Based Memory Key Recovery Under Circuit Aging
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Solution Overview
Problem
Nonvolatile memory systems face challenges in maintaining data confidentiality due to the aging of circuit element characteristics in physical unclonable functions (PUFs), which narrows the error correction capability and increases the amount of auxiliary data required for error correction.
Innovation Solution
The memory system incorporates a controller that generates auxiliary data with aging information to correct for shifts in PUF output distributions, ensuring invariant error correction capability by accounting for the inherent aging tendency of circuit elements, thereby preventing deterioration of error correction and reducing the amount of auxiliary data needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction methods are used without considering aging, then the error correction capability deteriorates over time due to PUF aging, but incorporating aging information increases the amount of auxiliary data required
Solution Approach 1:
The patent applies preliminary action by measuring and recording the aging tendency of the PUF circuit element during the enrollment phase before actual use. The aging information (first through fourth aging measurements) is captured in advance and stored as auxiliary data, allowing the system to proactively compensate for future aging effects without requiring additional data during operation.
Solution Approach 2:
The patent changes the parameters of the auxiliary data by incorporating specific aging information that characterizes the temporal drift of the PUF output. Instead of using static error correction codes, the system uses dynamic parameters including aging measurements taken at different time points, enabling the error correction to adapt to the changing PUF characteristics over time.
2Quantity of substance
If the amount of auxiliary data is reduced, then storage efficiency improves, but error correction capability under aging conditions deteriorates
Solution Approach 1:
The patent extracts only the essential aging information from the PUF measurements - specifically the drift between initial and subsequent measurements at different time points. By taking out only the critical aging parameters (the difference between first/second and third/fourth measurements) rather than storing complete measurement sequences, the system minimizes auxiliary data while maintaining error correction capability.
Solution Approach 2:
The patent creates a simplified copy or representation of the aging behavior through mathematical modeling. The aging information serves as a compressed model that captures the essential drift characteristics, allowing the system to reconstruct or compensate for aging effects without storing complete historical measurement data, thus reducing auxiliary data requirements.
Data Source
AI summary
According to one embodiment, a memory system includes a nonvolatile memory and a controller. The controller includes a circuit element. At a first timing, the controller acquires first identification information from a characteristic of the circuit element. The controller generates, using the first identification information, an encryption key for data to be written to the nonvolatile memory. The controller acquires aging information of the first identification information. The controller generates, using the aging information, auxiliary data for correcting an error included in second identification information, which is acquired from the characteristic of the circuit element at a second timing, to restore the first identification information.