Flash Memory Replay-Protected Block Write Count Management
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Solution Overview
Problem
Flash memory devices, particularly NAND Flash, face challenges in managing replay-protected memory blocks (RPMBs) due to the need for higher security and efficient data management, especially during power failures which can lead to data integrity issues.
Innovation Solution
A data storage device with a controller that manages RPMBs by dividing storage space into blocks and pages, where each page is programmed with a write count, and utilizes a FAT block for data buffering, ensuring data integrity by verifying MAC values and handling power failures through specific allocation and validation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If replay-protected memory blocks are used to enhance data security, then data security is improved, but device complexity increases due to additional management requirements
Solution Approach 1:
The storage space is divided into regular memory blocks and replay-protected memory blocks (RPMBs), with each RPMB further divided into pages. This segmentation allows independent management of secure and non-secure areas, enhancing security without overwhelming the entire storage system with complex management protocols.
Solution Approach 2:
The controller pre-manages RPMB allocation and maintains a File Allocation Table (FAT) that tracks the status of each page within RPMBs. By preparing the management structure in advance and maintaining real-time tracking, the system simplifies the actual data writing process while ensuring security requirements are met.
2Reliability
If write count is programmed into each page to track write operations, then data integrity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The write count is merged into the same page structure as the actual data, using the remaining space in each page after storing data. This approach tracks write operations without requiring separate storage structures, maintaining data integrity while avoiding additional programming steps that would increase precision requirements.
3Reliability
If FAT block is used for data buffering with MAC value verification, then data security is improved, but device complexity increases
Solution Approach 1:
The File Allocation Table (FAT) provides real-time feedback on the status of each page in the RPMB, tracking whether pages are empty, valid, or invalid. The MAC value verification provides feedback on data authenticity. This feedback mechanism ensures security without requiring complex manual tracking systems.
Solution Approach 2:
The controller automatically performs MAC value verification and updates the FAT table without requiring external intervention. The system self-manages the security verification process and automatically updates allocation status, reducing the complexity burden on external control systems.
4Reliability
If power failure protection mechanisms are implemented, then reliability is improved, but loss of time occurs during power restoration verification
Solution Approach 1:
The FAT table continuously tracks the allocation status of all pages during normal operation, maintaining an up-to-date record before any power failure can occur. This preliminary tracking eliminates the need for extensive verification after power restoration, as the system already knows the expected state of each page.
Solution Approach 2:
The patent replaces complex post-power-failure verification mechanisms with a simpler system that uses the pre-maintained FAT table for quick status checks. Instead of mechanically verifying each page after power restoration, the system uses the already-populated FAT information to quickly determine what actions are needed, significantly reducing verification time.
Data Source
AI summary
A data storage device using a FLASH memory with replay-protected blocks. The storage space of the FLASH memory is divided into blocks and each block is further divided into pages. A controller is provided in the data storage device to couple to the FLASH memory. The controller manages at least one replay-protected memory block of the FLASH memory. The controller programs two pages into the at least one replay-protected memory block and each page is programmed with a write count of the at least one replay-protected memory block.