Structured Document Signature Hash Tree Adaptation Verification

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Solution Overview

Problem

Conventional digital signature methods for structured documents fail to verify the authenticity of adapted elements and cannot detect unauthorized additions or deletions, leading to issues in ensuring the integrity of multimedia content delivery across varying user environments.

Innovation Solution

A structured document signature device that associates each element with an adaptation policy, constructs a hash tree incorporating hash values of child elements and values as attributes, and adds a digital signature to the root, allowing verification of adaptations and authenticity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a digital signature is added to the digest value of the overall structured document using conventional methods, then the authenticity of the overall document can be verified, but the authenticity of adapted elements cannot be verified and unauthorized modifications cannot be detected

Engineering Contradiction:

Improveauthenticity verificationVSAvoiddocument adaptation capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the digital signature verification into multiple levels: overall document authentication and individual element authentication. By attaching digital signatures to both the overall document and to each element's digest value, the system enables verification of both the complete document and its individual components after adaptation, resolving the contradiction between overall authenticity verification and adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by pre-calculating and attaching digital signatures to element digest values before adaptation occurs. This preliminary authentication of individual elements allows the system to verify authenticity even after the document has been adapted, maintaining both reliability and adaptability.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If digest values of all elements are concatenated with the overall document digest value, then element authenticity can be verified, but the system complexity and processing overhead increase

Engineering Contradiction:

Improveelement authenticity verificationVSAvoidsignature processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the authentication process into independent element-level operations. Each element has its own digest value and digital signature that can be verified independently, avoiding the need to process the entire concatenated structure. This segmentation reduces processing complexity while maintaining comprehensive element authenticity verification.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by only signing and verifying elements that are actually present and relevant in the adapted document, rather than processing all possible elements. This selective approach reduces processing overhead while maintaining sufficient verification coverage for the actual content.

Inventive Principle:

Principle #16Partial or excessive action

3Adaptability or versatility

If the structured document is modified by adaptation, then the document can be customized for different environments, but the authenticity of the modified document cannot be verified

Engineering Contradiction:

Improvedocument customizationVSAvoidauthenticity verification

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs preliminary authentication by attaching digital signatures to element digest values before adaptation modifies the document. This preliminary action establishes a baseline of authenticity that persists through adaptation, allowing verification that the adapted document maintains its authenticity while being customized for different environments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where the adapted document includes information about the adaptation process and the original authentication data. This feedback allows verification systems to confirm that adaptations were performed authorized and maintain authenticity, resolving the contradiction between customization and verification.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7639818B2Structured document signature device, structured document adaptation device and structured document verification device

Publication Date: 2009.12.29 NTT DOCOMO INC

AI summary

A structured document signature device includes an adaptation policy associator configured to associate each element forming a structured document with an adaptation policy indicating an action which can be adapted to a child element of the element or a value of the element; a hash tree constructor configured to insert a hash value of the child element of the element or a hash value of the value of the element into the structured document as an attribute value of the element, and to construct a hash tree including the hash value; a digital signature adder configured to add a digital signature to a root of the hash tree and the adaptation policy; and an output configured to output the structured document and the digital signature.