Modified Bundle Signature Verification via Catalog Segmentation

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Solution Overview

Problem

Existing methods for verifying bundles in distributed environments fail when files are removed from a signed bundle, as they do not allow for the verification of modified bundles without causing verification to fail.

Innovation Solution

The system allows for the verification of modified signed bundles by maintaining a list of removed files and ensuring that only specified files have been removed, using a catalog digital signature that remains unchanged, enabling successful verification even after files are removed from the bundle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bundle signature verification is used, then bundle authenticity is protected, but verification fails when files are removed from the bundle

Engineering Contradiction:
Improvebundle verification reliabilityVSAvoidbundle modification capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The verification process is segmented into two independent parts: verifying the catalog signature (which remains unchanged) and verifying the file list (which tracks removed files). This allows the system to verify bundle authenticity while accommodating legitimate file removals, resolving the contradiction between verification reliability and modification capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary action by maintaining a record of removed files in advance. The file list is prepared beforehand to specify which files are expected to be absent, allowing the verification process to anticipate and accept legitimate modifications without failing, thus enabling bundle modification capability while maintaining verification reliability.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If files are removed from a signed bundle, then distribution flexibility is improved, but verification authenticity fails

Engineering Contradiction:
Improvebundle distribution flexibilityVSAvoidsignature verification authenticity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The file list acts as an intermediary between the catalog signature and the actual files in the bundle. It mediates the verification process by providing information about which files are expected to be removed, allowing the system to maintain verification authenticity while accommodating distribution flexibility through file removals.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system prepares the file list in advance to document which files will be removed from the bundle. This preliminary action allows the verification process to authenticate the bundle despite legitimate file removals, resolving the contradiction between distribution flexibility and verification authenticity.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If strict signature verification is enforced, then security is maintained, but modified bundles cannot be verified

Engineering Contradiction:
Improvesecurity verificationVSAvoidmodified bundle verification
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The verification process is divided into segments: strict verification of the catalog signature (maintaining security) and flexible verification of the file list against the bundle contents (enabling modified bundle verification). This segmentation allows both security maintenance and ease of operation for modified bundles.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The file list is prepared in advance to specify which files are expected to be removed. This preliminary action enables the verification process to easily handle modified bundles by comparing the actual contents against the expected contents documented in the file list, while still maintaining strict security verification of the catalog signature.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2116953B1Modified bundle signature verification
Publication Date: 2018.12.26 BLACKBERRY LTD
  • EP2116953B1 patent drawingFigure 1a~1b
  • EP2116953B1 patent drawingFigure 2
  • EP2116953B1 patent drawingFigure 3

AI summary

Systems, devices, and methods for modifying a signed bundle and verifying the modified bundle are disclosed. A signed bundle may be modified by removing a file specified in a server file list from a plurality of files in the bundle. The signed bundle comprises a catalog of files in the signed bundle and their associated hashes. The modified bundle includes the remaining files of the signed bundle that are not specified in the server file list and the catalog file of the signed bundle, the catalog signature of the signed bundle. The modified bundle may be verified by verifying the catalog signature of the modified signed bundle, and checking that the files specified in the catalog are either in the modified signed bundle or specified in the server file list. The hashes of the files in the modified signed bundle may also be checked to verify the modified signed bundle.