File Protection via Entry Value Modification in Flash Memory
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Solution Overview
Problem
There is a need to protect files stored on rewritable non-volatile memory modules, such as flash drives, from unauthorized access, as personal data stored on these devices is often shared and requires secure protection.
Innovation Solution
A file protection method and system that groups physical blocks into data and spare areas, configures logical addresses to form partitions including a file allocation document area and a file area, and performs a file protection enabling procedure by generating an entry value backup and changing the entry value in the file allocation document, making the file inaccessible to unauthorized users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If file protection is implemented by modifying entry values in the file allocation document, then file security against unauthorized access is improved, but the complexity of the file management system increases
Solution Approach 1:
The patent segments the file allocation document into multiple entries, each containing an entry value that points to the next cluster in the file. By modifying individual entry values to point to invalid or reserved clusters, the system protects specific files without affecting the overall file allocation structure. This segmentation allows selective protection while maintaining system simplicity.
Solution Approach 2:
The patent introduces an intermediary protection mechanism that acts between the file data and the file allocation document. By modifying entry values to point to reserved or invalid clusters, this intermediary layer prevents unauthorized access to protected files while leaving the actual file data unchanged. The protection is achieved through controlling the path to the data rather than encrypting or hiding the data itself.
2Reliability
If entry values are modified to prevent file access, then unauthorized access is blocked, but the ability to recover or restore files is worsened
Solution Approach 1:
The patent performs preliminary action by creating a backup of the original entry values before modifying them for protection. This backup is stored securely, allowing the system to restore the original file allocation paths when authorized users need to access protected files. The preliminary backup ensures that file recovery is straightforward while maintaining strong protection during normal operation.
Solution Approach 2:
The patent implements a discard-and-recover mechanism where the original entry values are temporarily discarded (modified to invalid pointers) for protection purposes, but can be recovered from secure backups when needed. This allows the system to switch between protected state (entry values modified) and accessible state (entry values restored) based on authorization, balancing security with recoverability.
Data Source
AI summary
A file protecting method and system and a memory controller and a memory storage apparatus using the same are provided. The file protecting method includes performing a file protection enabling procedure for a file to generate an entry value backup according to at least one entry value corresponding to at least one cluster storing the file, which is recorded in a file allocation document, store the entry value backup in a secure storage area and change the entry value corresponding to the cluster storing the file in the file allocation document, wherein the file cannot be read according to the changed entry value. Accordingly, the file stored in the memory storage apparatus the can be effectively protected from being accessed by an un-authorized person.