Practical Non-Interactive Blind Signatures for Anonymous Digital Tokens → Research

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Briefing

This foundational research addresses the critical challenge of practical non-interactive blind signatures (NIBS) compatible with existing public-key infrastructure. It proposes novel generic constructions leveraging Yao’s garbled circuit techniques, enhancing the utility of blind signatures for anonymous digital tokens and privacy-preserving systems. This breakthrough fundamentally advances the deployment of trust-minimized, privacy-preserving mechanisms across various blockchain architectures and digital financial technologies.

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Context

Prior to this work, while the concept of non-interactive blind signatures for random messages was introduced, practical schemes compatible with widely used public-key infrastructure (PKI) keys remained an open problem. Existing blind signature protocols inherently required interaction between parties, limiting their applicability in scenarios demanding efficiency and offline capabilities, or where the recipient’s choice of message was not critical.

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Analysis

This paper’s core mechanism involves a generic construction of non-interactive blind signatures. It fundamentally differs from previous approaches by enabling the signer to create a pre-signature, which the recipient then uses with their secret key to finalize a signature on a random message, without further online interaction. This is achieved by replacing interactive oblivious transfer with a non-interactive variant and constructing it to support standard RSA public keys, as well as integrating with pairing-based Pointcheval-Sanders and BBS signatures. The underlying logic leverages Yao’s garbled circuits to ensure the message is an output of the finalization process, guaranteeing blindness and non-interaction.

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Parameters

Core Concept → Non-Interactive Blind Signatures (NIBS)
Key Authors → Lucjan Hanzlik, Eugenio Paracucchi, Riccardo Zanotto
Foundational Basis → Yao’s Garbled Circuit Techniques
Key Innovation → Practical construction with standard PKI keys (e.g. RSA)
Primary Application → Anonymous digital tokens, Privacy Pass
Conference → EUROCRYPT 2025

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Outlook

This research opens significant avenues for enhancing privacy and security in decentralized applications. In the next 3-5 years, these practical non-interactive blind signatures could unlock more efficient and secure e-cash systems, anonymous credential services, and robust privacy-preserving payment protocols. The ability to issue tokens offline and in batches, compatible with hardware security modules, will drive broader adoption of privacy-focused digital assets and mitigate security risks in cryptocurrency exchanges.

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Verdict

This work fundamentally advances the practical deployment of non-interactive blind signatures, establishing a crucial cryptographic primitive for scalable, privacy-preserving digital token ecosystems.

Signal Acquired from → IACR ePrint