PQC Hash Signatures for Legacy Documents Facing Quantum Forgery
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Solution Overview
Problem
The threat of quantum computers poses a significant risk to classical encryption algorithms, potentially allowing attackers to forge or modify already signed documents, which are currently vast in number and impractical to re-sign using Post-Quantum Cryptography (PQC) algorithms.
Innovation Solution
Generate a hash of already signed documents using classical encryption algorithms and sign the hash with PQC algorithms to protect against quantum attacks, ensuring the integrity and authenticity of the documents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If classical encryption algorithms are used to sign documents, then the signing process is efficient and widely compatible, but the signatures become vulnerable to quantum computer attacks
Solution Approach 1:
The solution segments the protection mechanism into two independent layers: the original classical digital signature and a new PQC signature on the document hash. This segmentation allows each signature type to operate independently with its own strengths, avoiding the need to replace the entire cryptographic system while adding quantum-resistant protection.
Solution Approach 2:
The patent creates a composite cryptographic system by combining classical encryption algorithms and Post-Quantum Cryptography algorithms. This composite approach leverages the efficiency and widespread compatibility of classical algorithms while incorporating the quantum-resistant properties of PQC, achieving enhanced security without complete system replacement.
2Reliability
If every already signed document is re-signed with PQC algorithms, then quantum resistance is achieved, but the time and effort required is complex and practically impossible
Solution Approach 1:
The patent extracts only the essential element that needs protection - the document's hash value - and applies PQC signing only to this extracted component. This avoids the need to re-sign entire documents or involve original signers, significantly reducing the time and effort required while maintaining security against quantum attacks.
Solution Approach 2:
The solution performs preliminary hashing of the document content before applying the PQC signature. This preliminary action creates a fixed-size representation that is efficient to sign with PQC algorithms, enabling bulk processing of already signed documents without requiring access to original documents or signers.
3Ease of manufacture
If a PQC signature is applied to the document hash instead of the original document, then quantum security is achieved with minimal effort, but the process requires hashing the signed document
Solution Approach 1:
The patent introduces a hash function as an intermediary between the original signed document and the PQC signature. This intermediary transforms the potentially large and complex signed document into a fixed-size hash value, making the PQC signing process efficient and standardized while maintaining the integrity link to the original document.
4Productivity
If classical encryption is used, then document signing is widely accepted and efficient, but the signatures are at risk from future quantum computing capabilities
Solution Approach 1:
The patent applies preliminary anti-action by adding PQC signatures to documents before quantum computers become capable of breaking classical encryption. This proactive measure creates a defensive layer that will remain valid even after quantum computers advance, preventing future security breaches rather than responding to them after they occur.
Data Source
AI summary
Protecting already signed documents and code using classical encryption algorithms includes obtaining a signed document where the signed document has previously been signed using a classical encryption algorithm; determining a hash of the signed document; encrypting the hash of the signed document to obtain a digital signature, wherein the encrypting utilizes a private key associated with a Post-Quantum Cryptography (PQC) algorithm; and attaching the digital signature to the signed document to provide a PQC signed document which is protected against quantum attacks on the classical encryption algorithm. Verification includes receiving a document that purports to be the PQC signed document; decrypting the digital signature using a public key associated with the private key to obtain the hash; determining a second hash of the document that purports to be the PQC signed document; and comparing the hash and the second hash to determine validity.