Filesystem Secure Erasure via Block Overwriting
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Solution Overview
Problem
Conventional methods for securely deleting data from hard disks lack specificity and require administrative input, often resulting in wasteful destruction of entire disks and failure to erase data completely, especially after defragmentation.
Innovation Solution
Implementing a filesystem that automatically securely erases deleted and truncated files by using a secure erase flag to identify sensitive content and overwrite blocks before reusing them, eliminating the need for administrative input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional deletion methods are used to delete files, then the filesystem can quickly free blocks for reuse, but the underlying blocks containing file data are retained and may be recovered until the filesystem reuses them
Solution Approach 1:
The filesystem performs secure erasure by overwriting block data with random patterns before freeing the blocks for reuse. This preliminary action ensures that even if blocks are reused quickly, the original data cannot be recovered, thus maintaining both deletion speed and data security.
2Reliability
If organizations physically destroy or clean entire hard drives to ensure secret data does not fall into wrong hands, then data security is improved, but the entire disk is wasted even if only small portions contained sensitive data
Solution Approach 1:
The invention applies secure erasure at the block level rather than the entire disk level. The filesystem identifies and secures only the specific blocks that contained sensitive data, allowing the rest of the disk to remain fully usable. This segmentation approach eliminates storage capacity waste while maintaining data security.
Solution Approach 2:
The filesystem implements different treatments for different blocks based on their content sensitivity. Blocks containing sensitive data are securely erased, while other blocks remain available for normal use. This local quality approach ensures security is applied only where needed, preventing unnecessary loss of storage capacity.
3Reliability
If host computers run programs to securely delete entire filesystems containing sensitive data, then data security is improved, but additional administrative burden is placed on system administrators who must track sensitive information and deletion attempts
Solution Approach 1:
The filesystem automatically performs secure erasure of blocks containing sensitive data without requiring external host programs or administrative intervention. The filesystem itself tracks and manages sensitive data blocks, applying secure deletion autonomously when files are deleted or truncated. This self-service approach eliminates the need for administrators to manually track and delete sensitive information.
Solution Approach 2:
The filesystem integrates multiple functions into a single system: normal file operations, sensitive data identification, and secure erasure. By combining these functions within the filesystem itself rather than requiring separate host programs, the system reduces administrative complexity while maintaining comprehensive data security.
4Speed
If filesystems defragment data to improve performance, then access speed is improved, but old data may remain on disk indefinitely creating security risks
Solution Approach 1:
The filesystem implements a feedback mechanism where the secure erasure flag status is tracked during defragmentation operations. When blocks are moved or reused during defragmentation, the system checks the secure erasure flag and applies appropriate secure deletion protocols. This feedback loop ensures that performance optimization through defragmentation does not compromise data security.
Data Source
AI summary
In one embodiment, a method is performed by a computing device configured to manage a filesystem stored on persistent storage. The method includes (a) receiving a command to delete a range of a file of the filesystem, (b) removing blocks of the range from being accessible to the filesystem as part of the file, (c) overwriting a block of the range using a secure erasure technique, and (d) subsequent to overwriting the block, freeing the block for re-use by the filesystem. A data storage system, apparatus, and computer program product for performing a similar method are also provided.