Hash-Chain Subject Documentation for Tamper-Proof Change Histories

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Solution Overview

Problem

Existing systems lack secure, tamper-proof, and transparent methods for documenting the history of changes in subjects such as properties, inventories, scientific experiments, business accounts, and medical records, which are vulnerable to attacks and alterations.

Innovation Solution

The use of hash chains to document subjects, where each block in the chain includes a fingerprint of the previous block, ensuring an ordered and immutable record, stored in a distributed manner to prevent unauthorized modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional digital documentation systems are used to record subject changes, then the system is easy to operate and implement, but the documentation is vulnerable to tampering and attacks, lacking security and integrity

Engineering Contradiction:
Improvesecurity and integrity of documentationVSAvoidcomplexity of documentation system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The documentation system is segmented into discrete blocks, where each block contains a subset of transaction data and a cryptographic hash reference to the previous block. This segmentation creates a chain structure that provides security through distribution while maintaining operational simplicity through modular design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Cryptographic hash functions serve as intermediaries between data blocks, creating immutable links that verify integrity without requiring complex trust relationships. The hash chain acts as a mediator that automatically validates the sequence and authenticity of documentation entries.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If distributed storage is implemented to prevent unauthorized modifications, then the fault tolerance and security improve, but the system complexity and computational requirements increase

Engineering Contradiction:
Improvefault tolerance of documentation systemVSAvoidcomplexity of distributed storage system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system creates multiple copies of the hash chain across distributed nodes, ensuring that the documentation exists in identical form at multiple locations. This copying approach provides fault tolerance through redundancy while simplifying the system compared to complex distributed consensus mechanisms, as nodes simply replicate and verify the chain structure.

Inventive Principle:
Principle #26Copying

3Reliability

If hash chains are used to create immutable records, then the transparency and auditability improve, but the ability to modify or update records is reduced

Engineering Contradiction:
Improvetransparency and auditability of documentationVSAvoidflexibility to modify documentation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary cryptographic hashing of each block before adding it to the chain, creating an immutable reference that prevents future modification. This preliminary action ensures transparency and auditability from the outset, while the immutable structure itself becomes the feature that provides security rather than a limitation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3803652B1Method and system for secure digital documentation of subjects using hash chains
Publication Date: 2025.10.29 INTUIT INC
  • EP3803652B1 patent drawingFigure 1
  • EP3803652B1 patent drawingFigure 2A~2B
  • EP3803652B1 patent drawingFigure 3A~3B

AI summary

The invention relates to a method for documenting subjects using hash chains. The method includes receiving a subject data write request including one or more subject attribute values, generating a fingerprint from a current last block of a hash chain, and generating a payload from the subject data, the payload including the one or more subject attribute values and one or more keys identifying the one or more subject attribute values. The method further includes appending a block to the hash chain. The appended block includes the payload and the fingerprint.