Hash Chain Verification for Multi-Signature Integrity
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Solution Overview
Problem
Existing techniques for aggregating multiple signatures in electronic documents do not effectively prevent unauthorized operations, such as signature replacement, without disclosing the modified document to the verifier, especially when the document creator and reviewers belong to different organizations.
Innovation Solution
A method involving a first computer system calculating hash values for an original and modified document, combining these values to create a hash chain, and transmitting information to a second computer system to verify the validity of the signatures without disclosing the original or modified documents, using a shared random number to ensure the integrity of the signature verification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the verifier views all modified version documents and calculates hash values to verify multi-signatures, then the verification reliability is improved, but the document confidentiality is compromised
Solution Approach 1:
The verification process is segmented into two independent parts: (1) the verifier only receives and verifies hash values and aggregate signatures without accessing the actual documents, and (2) the document chain integrity is maintained through cryptographic hashing. This segmentation allows verification reliability to be improved while preserving document confidentiality, as the verifier works with segmented hash data rather than complete documents.
Solution Approach 2:
Hash values serve as an intermediary between the documents and the verification process. The hash values act as a mediator that carries the essential verification information without exposing the actual document content. This intermediary mechanism enables the verifier to confirm signature validity while the original documents remain confidential within the creating organization.
2Loss of information
If the existing multi-signature aggregation technique is used without document disclosure, then the document confidentiality is maintained, but the ability to detect unauthorized operations is reduced
Solution Approach 1:
Hash values are calculated and bound to each document version in advance before the verification process. This preliminary action creates a cryptographic commitment to the document content at each stage. When verification occurs later, the pre-calculated hash values enable the verifier to detect any unauthorized operations (such as signature replacement) without needing to access the actual documents, thus maintaining both confidentiality and reliability.
Solution Approach 2:
The system implements a feedback mechanism where hash values from each document version are chained together, creating a verifiable history. The verifier receives feedback in the form of hash values and aggregate signatures that confirm the integrity of the signature chain. This feedback loop enables detection of unauthorized operations while keeping the documents confidential.
3Loss of information
If hash values and aggregate signatures are transmitted to the verifier without documents, then the document confidentiality is preserved, but the verification complexity increases
Solution Approach 1:
Multiple individual signatures are merged into a single aggregate signature using Schnorr multi-signature aggregation. This combining process reduces the verification complexity by allowing the verifier to validate all signatures in one operation rather than processing each signature separately. The aggregate signature, together with the hash values, provides a streamlined verification process that maintains document confidentiality while reducing computational complexity.
Data Source
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AI summary
A verification method implemented by a first system including a plurality of computers, the method includes: calculating a first hash value for an original document; calculating a second hash value for an original document by using the first hash value; calculating a first modified version's first hash value for the first modified version document; calculating a first modified version's second hash value that is a hash value obtained by combining the first modified version's first hash value and the original document's second hash value; in response to a second modified version document obtained by modifying the first modified version document, calculating a second modified version's first hash value for the second modified version document; and calculating a second modified version's second hash value that is a hash value obtained by combining the second modified version's first hash value and the first modified version's second hash value.