S-Cred: An accountable anonymous credential scheme with decentralized verification and flexible revocation

Abstract

The popularization of digital credentials brings convenience to people, but it also increases the risks of privacy leakage and capability abuse. Designing an accountable anonymous credential scheme offers a promising solution to this problem. However, most existing schemes of accountable anonymous credentials cannot effectively support both decentralized verification and flexible revocation. In this paper, we present S-Cred, an accountable anonymous credential scheme with decentralized verification and flexible revocation, to provide a delegation issuance method for credentials. The ownership of attributes will be transferred to users' temporary identities on the blockchain. In order to prevent credentials misuse, we also design several constraint mechanisms for tracing misbehaving users and revoking their credentials. We further construct a non-fungible obfuscation mechanism by introducing special roles called cloakers. In addition, this paper conducts analysis on security, functionality, efficiency and performance. The results show that S-Cred combines decentralized authentication and flexible revocation with a low computational cost in verification, which demonstrates the practicality of our solution.