Flash Translation Layer Erasure for Secure File Deletion

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Solution Overview

Problem

Conventional file systems do not effectively erase deleted files from storage devices, allowing recovered data to remain intact and potentially accessible, which is a concern for privacy and security when sensitive information is involved.

Innovation Solution

A data processing system that sends a file delete command to an external storage device with an erase before write memory, specifying a logical address and data to be invalidated, and uses a Flash Translation Layer (FTL) module to manage memory units, ensuring that deleted files are physically erased by identifying and marking units as containing invalid data for immediate erasure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional file systems logically delete files by updating metadata, then file system operation speed is improved, but data security deteriorates because deleted files remain recoverable

Engineering Contradiction:

Improvefile deletion speedVSAvoiddata recoverability

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary erasure action by sending a delete command to the storage device that triggers immediate physical erasure of file data before the file system completes its logical deletion process. This preliminary physical erasure prevents any subsequent recovery attempts, resolving the contradiction between fast logical deletion and data security.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention introduces an intermediary layer between the file system and storage device - a controller that intercepts file delete commands and translates them into erasure commands for the storage device. This intermediary ensures that logical deletion requests from the file system are converted into immediate physical erasure actions, eliminating the security vulnerability while maintaining file system compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If file data is physically erased upon deletion, then data security is improved, but storage device complexity increases due to additional erasure management

Engineering Contradiction:

Improvedata recoverabilityVSAvoidstorage system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The storage device is designed with self-service capability where the controller automatically manages the erasure process without requiring complex external intervention. When a delete command is received, the controller autonomously identifies the file data location and performs erasure, then updates its internal mapping tables. This self-service approach minimizes the need for complex external management systems while ensuring secure erasure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention merges the erasure function with the existing file deletion workflow by integrating the erasure command generation and execution within the storage device controller. Instead of requiring separate erasure hardware or complex software layers, the controller combines logical deletion handling with physical erasure execution, simplifying the overall system architecture while achieving secure deletion.

Inventive Principle:

Principle #5Merging (Combining)

3Quantity of substance

If file data remains on storage device after logical deletion, then storage space is preserved for overwriting, but data privacy is compromised

Engineering Contradiction:

Improveavailable storage spaceVSAvoidfile data privacy

Core Design Contradiction:

Quantity of substanceVSLoss of information

Solution Approach 1:

The system converts the potential harm of data remaining on storage devices into a benefit by implementing selective erasure. Instead of erasing entire storage blocks (which would reduce available space), the controller precisely erases only the specific file data that was deleted, leaving other data intact. This converts the security risk of data remaining into a controlled erasure process that maintains both privacy and storage efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention applies local quality by performing erasure only on specific data regions rather than uniformly erasing entire storage blocks. The controller identifies the exact location of deleted file data and erases only those specific memory units, leaving other areas of the storage device unchanged and available for use. This localized approach maintains storage efficiency while ensuring data privacy.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8838875B2Systems, methods and computer program products for operating a data processing system in which a file delete command is sent to an external storage device for invalidating data thereon

Publication Date: 2014.09.16 SAMSUNG ELECTRONICS CO LTD

AI summary

A data processing system that includes a host system and an external data storage device with an erase before write memory device thereon can be operated by sending a file delete command from the host to the data storage device for one or more files stored thereon. The file delete command may specify a logical address and data to be invalidated associated with the deleted file. The data storage device may identify one or more units of memory allocation in the erase before write memory as containing invalid data based on the specified logical address and data to be invalidated. The data storage device may maintain a data structure that associates physical addresses for units of memory allocation in the erase before write memory with indications of whether the units of memory allocation contain invalid data. The data structure may be used to mark units of memory allocation associated with deleted files as containing invalid data.