Multi-Authority Anonymous Credentials With Efficient and Decentralized Supervision

Anonymous credential is widely used in online services, where issuers in authorities issue credentials to users and then users can selectively and privately prove their identities and attributes. However, users may misbehave under anonymous settings. Therefore, we need to trace the credential proof to obtain the user’s identity and link credential proofs to achieve supervision. Existing solutions either have the single point of failure problem or require multiple supervisors perform threshold computations on all users’ identities, it is inefficient in practice especially when the number of users increases. In this paper, we present a credential management system in multiple authorities with efficient and decentralized supervision. Specifically, we design a multi-authority credential management architecture, where each issuer in authorities issues credentials to users and supervisors trace and link credential proofs in multiple authorities. Then, we present efficient and decentralized credential proof tracing and linking protocols, where more than threshold supervisors can trace credential proofs to obtain users’ identities and generate users’ linking keys. Verifiers can link each malicious user’s credential proofs efficiently with those linking keys. We conduct experiments on our system in the WAN and LAN settings and compare it with another threshold attribute-based credential scheme. The experimental results demonstrate that our solution is efficient in practice.