Flash Memory PUF Authentication Stabilization via Cell Segmentation
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Solution Overview
Problem
Flash memory devices based on physical unclonable functions (PUFs) face challenges in consistently outputting the same authentication response when the same authentication challenge is used, due to variations in threshold voltages of memory cells.
Innovation Solution
A method for operating a flash memory system involves selecting memory cells, programming input data, reading cells to generate control information, dividing cells into first and second region memory cells based on threshold voltages, and setting read values to specific values to generate a consistent authentication response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory cells are used for PUF-based authentication, then device uniqueness and security are improved, but consistency of authentication response deteriorates due to threshold voltage variations
Solution Approach 1:
The patent divides the selected memory cells into at least one first region memory cell and at least one second region memory cell based on control information generated from reading the cells. This segmentation allows different read values to be assigned to different regions, compensating for threshold voltage variations and ensuring consistent authentication responses across multiple challenges.
Solution Approach 2:
The patent changes the read values of memory cells based on their region classification. By setting read values of first region memory cells to a first value and second region memory cells to a second value, the system compensates for threshold voltage variations and achieves consistent authentication responses despite manufacturing variations.
2Reliability
If memory cells are divided into different regions based on threshold voltage, then authentication response consistency is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary reading of selected memory cells to generate control information before the authentication challenge is finalized. This preliminary action identifies which cells fall into which regions, allowing the system to pre-establish the mapping between memory cells and their regions, thereby simplifying the subsequent authentication process despite the added complexity of region management.
Solution Approach 2:
The patent introduces control information as an intermediary between the memory cells and the authentication response generation. This control information, generated from reading the memory cells, serves as a mediator that guides the division into regions and the assignment of read values, managing the complexity of handling threshold voltage variations without requiring direct complex control of each individual cell.
Data Source
AI summary
Provided are a flash memory device, a flash memory system, and methods of operating the same. A method of operating a flash memory system includes selecting memory cells of a flash memory in response to an authentication challenge, programming pieces of input data into the selected memory cells, respectively, reading the selected memory cells and generating and storing control information, dividing the selected memory cells into at least one first region memory cell and at least one second region memory cell based on the control information, and setting read values of the at least one first region memory cell and the at least one second region memory cell as a first value and a second value, respectively, and generating an authentication response in the response to the authentication challenge.