Cryptographic Verification of Compressed Archives

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Solution Overview

Problem

Existing data integrity verification methods fail to detect alterations in the structure of archives, such as additions, changes, or deletions of objects and metadata, despite protecting the contents with hashcodes and signatures.

Innovation Solution

A method and system that digitally signs a compressed archive by embedding a signature data object within the same container as the compressed archive, using cryptographic protocols like CMS or XMLDsig, ensuring the authenticity of the archive without decompressing it and maintaining compatibility with existing archive reader tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a compressed archive is digitally signed with a cryptographic signature embedded in the same container, then the authenticity and integrity of the archive is verified, but the complexity of the data structure increases

Engineering Contradiction:
Improveauthenticity verificationVSAvoiddata structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the compressed archive data and its cryptographic signature into a single container structure. The signature is embedded within the same data structure as the archive, allowing verification of authenticity while maintaining a unified format that existing tools can process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cryptographic signature is nested within the container that also holds the compressed archive. This nested structure allows the signature to be integrated seamlessly with the archive data, providing verification capability without requiring a separate external signature file.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If existing archive reader tools are used to access compressed archives, then ease of operation is maintained, but the ability to detect structural alterations is lost

Engineering Contradiction:
Improvetool compatibilityVSAvoidstructural integrity detection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The container structure acts as an intermediary that wraps the compressed archive. This intermediary layer provides cryptographic verification capabilities while allowing existing archive reader tools to access the underlying compressed data through the same interfaces, thus bridging the gap between legacy tool compatibility and modern security requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The container structure serves multiple functions: it acts as both a wrapper for the compressed archive that existing tools can read, and as a cryptographic verification mechanism that detects structural alterations. This multi-functionality allows a single structure to maintain both ease of operation with existing tools and enhanced reliability for detecting tampering.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If the cryptographic signature is embedded within the same container as the compressed archive, then protection against time-to-check vulnerabilities is achieved, but the size of the data structure increases

Engineering Contradiction:
Improvevulnerability protectionVSAvoiddata structure size
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

By merging the signature and archive into a single container, the patent eliminates the separation between data and its verification mechanism. This prevents time-to-check vulnerabilities where the signature and archive could be accessed at different times, as they are now atomically stored together in one container structure.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3711325B1Cryptographic verification of a compressed archive
Publication Date: 2024.10.30 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3711325B1 patent drawingFigure 1
  • EP3711325B1 patent drawingFigure 2
  • EP3711325B1 patent drawingFigure 3

AI summary

The authenticity of a compressed archive is verified without decompressing the files and/or directories contained therein and without impeding existing archive reader tools and utilities. A container is produced that includes a signature component and a compressed archive component. The signature component contains a digital signature of the compressed archive and the compressed archive component contains the compressed archive. The signature component and the compressed archive component are constructed as independent components so that existing software tools that operate on a compressed archive can still function in their normal course of operation.