File System Block Tracking for Secure Data Deallocation

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Solution Overview

Problem

Existing storage systems face security challenges due to unencrypted data fragments remaining accessible after file operations like defragmentation and tiering, which can expose sensitive information to unauthorized access.

Innovation Solution

A computer-implemented method and system that includes a block tracking module to identify and render unallocated storage blocks unreadable by determining sets of unallocated blocks previously allocated to a data object and either encrypting or permanently erasing their content, ensuring secure deallocation across multiple storage tiers and systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If data blocks are deallocated after defragmentation or tiering operations, then storage efficiency and access speed are improved, but security is worsened because unencrypted data fragments remain accessible on the storage device

Engineering Contradiction:

Improveaccess speedVSAvoidunauthorized access to data

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system performs encryption of deallocated blocks as a preliminary action before the blocks are reused or made accessible. When a file is encrypted, the system proactively identifies and encrypts all previously allocated blocks that are now deallocated, preventing the security vulnerability before it can occur. This advance action ensures that even though blocks are deallocated for performance, they remain secure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary encryption layer between the file system and the physical storage blocks. The encryption module acts as a mediator that transforms the data content on deallocated blocks, so that even though the blocks exist physically on the storage device, their content is protected by encryption. This intermediary mechanism resolves the contradiction by allowing block deallocation for performance while maintaining security through encryption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If encryption is applied to data objects, then security is improved, but unencrypted historic fragments on deallocated blocks remain vulnerable

Engineering Contradiction:

Improvedata securityVSAvoidresidual unencrypted data

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The system applies local quality by treating allocated and deallocated blocks differently. When a file is encrypted, the encryption is not only applied to currently allocated blocks but also specifically to deallocated blocks that previously held file data. This localized encryption approach ensures that residual data on deallocated blocks is protected while maintaining normal file system operations on allocated blocks.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the potential harm of residual unencrypted data into a benefit by using the same encryption mechanism to protect both allocated and deallocated blocks. The encryption process, which might seem to add complexity, actually benefits security by ensuring that no unencrypted fragments remain, turning a security vulnerability into a security strength.

Inventive Principle:

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

3Object-affected harmful factors

If all blocks are encrypted to prevent unauthorized access, then security is improved, but system complexity and processing overhead increase

Engineering Contradiction:

Improvedata exposure riskVSAvoidencryption management complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system applies partial action by encrypting only the necessary blocks - specifically, deallocated blocks that previously held file data - rather than encrypting all blocks in the storage system. This selective approach maintains security for vulnerable blocks while avoiding the excessive complexity of universal encryption, optimizing the balance between security and system complexity.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11636230B2Securing deallocated blocks in a file system

Publication Date: 2023.04.25 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A computer-implemented method for operating a storage system comprising a file system for managing a data object in one or more storage blocks may be provided. The method comprising receiving from a file system manager a message indicating that the data objects is to be encrypted, determining, in response to the received message, a set of unallocated storage blocks that were previously allocated for storing at least a portion of the data object, and rendering content of the unallocated storage blocks of the set unreadable.