Nonvolatile Memory PUF Circuit for Stable Key Generation
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Solution Overview
Problem
Existing storage devices lack effective mechanisms to enhance security through unpredictable and unique key generation, which is crucial for secure data storage and authentication.
Innovation Solution
A storage device incorporating a physically unclonable function (PUF) circuit that utilizes a nonvolatile memory cell array with distinct memory cell groups, excluding specific threshold voltage ranges to generate unique PUF data, thereby enhancing security by excluding predictable bit cell groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If all memory cell outputs are used to generate PUF data, then the quantity of PUF data increases, but the security and stability deteriorate due to predictable bit cell groups
Solution Approach 1:
The patent extracts and excludes specific bit cell groups from the PUF data generation process. The PUF circuit identifies and removes edge bit cell groups (with extreme threshold voltages) and intermediate bit cell groups (with threshold voltages near the reference voltage) from the output of the memory cell array. This extraction of problematic elements resolves the contradiction by eliminating predictable data while preserving the quantity of usable PUF data from the remaining memory cells.
2Quantity of substance
If memory cells with extreme threshold voltages are included in PUF data, then the quantity of PUF data increases, but the predictability increases reducing security
Solution Approach 1:
The patent applies local quality by treating different regions of the memory cell array differently based on their threshold voltage characteristics. Edge bit cell groups (first and last groups) with extreme threshold voltages are identified and excluded, while intermediate groups are selectively processed. This localized treatment of different memory cell regions resolves the contradiction by eliminating predictable extreme values while maintaining data quantity from stable regions.
3Quantity of substance
If memory cells with threshold voltage near reference voltage are included in PUF data, then the quantity of PUF data increases, but the stability deteriorates
Solution Approach 1:
The patent extracts and removes intermediate bit cell groups whose threshold voltages fall within a predetermined range around the reference voltage. These intermediate groups are excluded from PUF data generation because their outputs are unstable and prone to fluctuation. This extraction resolves the contradiction by eliminating unstable data points while preserving the quantity of PUF data from memory cells with stable threshold voltage characteristics.
Data Source
AI summary
A storage device is provided. The storage device includes: a nonvolatile memory including memory cells divided into first and second memory cell groups; a memory controller; and a physically unclonable function (PUF) circuit configured to generate PUF data, based on an output of the second memory cell group, by excluding, from the output of the second memory cell group, outputs of a first exclusion area, a second exclusion area, and a third exclusion area, The first exclusion area has a threshold voltage equal to or greater than a first read level and less than a second read level, the second exclusion area has a threshold voltage less than a third read level that is less than the first read level, and the third exclusion area has a threshold voltage equal to or greater than a fourth read level that is greater than the second read level.