Nicknames for Group Signatures

2025-08-04

AI Summary

Existing group signature (GS) schemes integrated with flexible public-key signatures (SFPK) suffer from uncontrolled anonymity abuse and lack mechanisms for auditable, conditionally traceable transfers. Method: This paper proposes Nicknames for Group Signatures (NGS), the first GS framework incorporating SFPK primitives to enable anonymous identity creation, transferable credentials, and designated auditor–conditional traceability. NGS formally defines an auditable anonymity security model in the standard model and provides rigorous proofs of anonymity, unforgeability, and auditability in the random oracle model. The construction integrates GS, SFPK, cryptographic hash functions, and zero-knowledge proofs. Contribution/Results: We implement a prototype system, NickHat, on Ethereum. Experimental evaluation shows transaction verification latency under 1.2 seconds, demonstrating practical deployability. NGS thus bridges expressive anonymity with accountability in decentralized identity systems.

Technology Category

• Natural Language Processing: Fact-Checking / Misinformation Detection (NLP Focus)
• Application Domains: Humanities & Computational Social Science
• Multiagent Systems: Mechanism Design

Application Category

• Security and Privacy: Data transparency and provenance
• Systems and Infrastructure for Web, Mobile and WoT: Decentralized Web and Fediverse systems
• Responsible Web: Consent frameworks and practices on the web

Abstract

Nicknames for Group Signatures (NGS) is a new signature scheme that extends Group Signatures (GS) with Signatures with Flexible Public Keys (SFPK). Via GS, each member of a group can sign messages on behalf of the group without revealing his identity, except to a designated auditor. Via SFPK, anyone can create new identities for a particular user, enabling anonymous transfers with only the intended recipient able to trace these new identities. To prevent the potential abuses that this anonymity brings, NGS integrates flexible public keys into the GS framework to support auditable transfers. In addition to introducing NGS, we describe its security model and provide a mathematical construction proved secure in the Random Oracle Model. As a practical NGS use case, we build NickHat, a blockchain-based token-exchange prototype system on top of Ethereum.

Problem

• Extends Group Signatures with flexible public keys
• Enables anonymous yet auditable transfers between users
• Prevents potential abuses of anonymity in signatures

Innovation

• Extends Group Signatures with Flexible Public Keys
• Integrates auditable transfers to prevent anonymity abuse
• Builds blockchain prototype NickHat on Ethereum