A zero-knowledge-proof-based digital identity management scheme in blockchain

The traditional centralized digital identity management system (DIMS) has been subject to threats such as fragmented identity, single point of failure, internal attacks and privacy leakage. Emerging blockchain technology allows DIMSs to be deployed in it, which largely alleviates the problems caused by the centralized third party, but its inherent transparency and lack of privacy pose a huge challenge to DIMSs. In this regard, we leverage the smart contracts and zero-knowledge proof (ZKP) algorithms to improve the existing claim identity model in blockchain to realize the identity unlinkability, effectively avoiding the exposure of the ownership of attributes. Furthermore, we implement a system prototype named BZDIMS that includes a challenge-response protocol, which allows users to selectively disclose their ownership of attributes to service providers to protect users' behavior privacy. Performance evaluation and security analysis show that our scheme achieves effective attribute privacy protection and a wider application scope compared with the prior model. (C) 2020 Elsevier Ltd. All rights reserved.