Paper 2026/077

Formalizing Privacy in Decentralized Identity: A Provably Secure Framework with Minimal Disclosure

Zongbin Wang, Beijing Infosec Technologies Co., Ltd.

Abstract

This paper presents a formal framework for enhancing privacy in decentralized identity (DID) systems, resolving the inherent conflict between blockchain verifiability and the principle of minimal data disclosure. At its core, we introduce a provably secure cryptographic protocol that leverages attribute commitments on-chain and zero-knowledge proofs for off-chain validation. This approach allows users to demonstrably prove the validity of predicates about their attributes without revealing the underlying sensitive values. We formally define the security and privacy requirements for such a system—including consistency, attribute-based indistinguishability, and predicate-based indistinguishability—within a semi-honest adversarial model. We then construct a concrete scheme that realizes these properties under standard cryptographic assumptions. The proposed architecture is designed for full backward compatibility with W3C DID standards, ensuring practical deployability. Security analysis provides rigorous, provable guarantees, while performance evaluation confirms the efficiency of the core cryptographic operations, supporting its use in resource-constrained environments. This work establishes a foundational and analyzable basis for building decentralized identity systems where both accountability and user privacy are essential.

Note: This work has been accepted by IEEE CSF 2026.

BibTeX

@misc{cryptoeprint:2026/077,
author = {Yu Zhang and Zongbin Wang},
title = {Formalizing Privacy in Decentralized Identity: A Provably Secure Framework with Minimal Disclosure},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/077},
year = {2026},
url = {https://eprint.iacr.org/2026/077}
}