Deanonymizable Scoped Linkable Ring Signatures

2026-05-12

AI Summary

This work addresses the challenge of balancing privacy preservation and controllable identity traceability in applications such as medical consent management, where traditional ring signatures fall short. The paper proposes a novel ring signature scheme that uniquely integrates *scoped linkability* and a *k-of-N decentralized de-anonymization mechanism* within a unified framework. By leveraging scope identifiers and dynamic key mirrors, the scheme enables flexible cross-domain linkability control, while an embedded ElGamal component supports on-demand collaborative decryption. Notably, the construction requires no centralized arbitrator or additional commitments, and its security is formally proven in the random oracle model under the Elliptic Curve Discrete Logarithm Problem (ECDLP) and Decisional Diffie-Hellman (DDH) assumptions. The design achieves a practical synthesis of privacy and regulatory accountability, demonstrated through implementation in a blockchain-based medical consent system.

Abstract

Although ring signatures offer highly desirable privacy requirements like anonymity and ad-hoc group formation with signer autonomy, they partially lack trust requirements like linkability and accountability that are required for strict use-cases, such as consent management in healthcare. Existing signature schemes fail to natively integrate scoped linkability with decentralized accountability (on-demand deanonymization) in a single scheme without relying on separate commitments or a centralized opener. We therefore introduce Deanonymizable Scoped Linkable Ring Signatures (DSLRS). The originality of the DSLRS is manifold. DSLRS uses scopes (context identifiers) and dynamic key images to provide scoped linkability and unlinkability across different scopes. Decentralized accountability is provided thanks to two ELGamal components deeply embedded in the signature, and a decentralized deanonymization network of k-of-N nodes that can collaboratively extract the signer's public key. DSLRS scheme is defined and proved under the ECDLP and DDH hardness assumptions in the Random Oracle Model (ROM). Formal security definitions and formal reduction proofs are provided before introducing a blockchain-based instantiation for a consent management application using DSLRS.

Problem

• ring signatures
• scoped linkability
• decentralized accountability
• deanonymization
• consent management

Innovation

• Scoped Linkability
• Decentralized Deanonymization
• Ring Signatures
• Dynamic Key Images
• Accountability