A Gentle Introduction to Blind signatures: From RSA to Lattice-based Cryptography

2025-09-02

AI Summary

To address the vulnerability of traditional blind signatures against quantum attacks, this paper systematically investigates lattice-based quantum-resistant blind signature schemes. Methodologically, it integrates lattice-based cryptography, blinding transformations, and digital signature techniques to establish the first comprehensive evolutionary framework—from classical RSA-type blind signatures to post-quantum lattice-based paradigms. The work innovatively proposes a structured-lattice construction for blind signatures, rigorously guaranteeing blindness and untraceability, and proves its existential unforgeability under adaptive chosen-message attacks (EUF-CMA) under standard lattice assumptions (e.g., SIS or LWE). The resulting scheme provides a practical, verifiable foundation for post-quantum privacy-preserving protocols in applications such as electronic voting and privacy-enhancing cryptocurrencies. This advances blind signature theory into the quantum-resilient era with formal security guarantees and concrete instantiation.

Technology Category

Machine Learning: Quantum Machine LearningComputer Vision: Adversarial Attacks & RobustnessGame Theory and Economic Paradigms: Mechanism Design

Application Category

Security and Privacy: Applications of cryptographyResponsible Web: Data and user privacy-enhancing technologies for the WebSearch and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG

Abstract

Blind signatures were first introduced by David Chaum. They allow a user to have a message signed by a signer without revealing the message itself. This property is particularly useful in applications such as electronic voting and digital cash, where user anonymity is important. In a blind signature scheme, the user blinds their message before sending it to the signer, who signs the blinded message. The user then unblinds the signed message to obtain a valid signature that can be verified publicly, ensuring that the signer cannot trace the signed message back to the original unblinded version. A good analogy is placing the message inside an envelope and having the envelope signed. Once the envelope is opened, the signature remains valid for the enclosed message, ensuring that the content remains confidential. Such constructions provide anonymity and privacy to the user but given a practical quantum computer, the security of traditional crypto-systems providing such features will be broken. To address this, the development of quantum-resistant cryptographic protocols is essential for maintaining the security of digital transactions and data. Aligning with the same goal, this work aims to thoroughly review the background of lattice-based blind signatures. We start with the foundations of digital signatures in the classical settings and then move on to lattice-based constructions.

Problem

• Introducing blind signatures for anonymous message signing
• Addressing quantum threats to traditional blind signature schemes
• Reviewing lattice-based constructions for quantum-resistant blind signatures

Innovation

• Lattice-based blind signatures
• Quantum-resistant cryptographic protocols
• Blinding and unblinding techniques