Traceable Revocable Anonymous Registration Scheme with Zero-knowledge Proof on Blockchain

Abstract

User registration is the beginning of the life cycle of an account for most information systems. Some registration servers have special requirements for the validity of the registrant's identity and attributes, and thus demand his real-life identity and raw attributes for verification, which poses a great threat to privacy. However, the exposure of the registrant's real-life identity and raw attributes is not necessary, as long as he can prove to the server that he is associated with a real-life identity (RId) that fulfills the requirements. In this paper, we propose the concept of anonymous registration, with which a user can register an anonymous identity (AId) without privacy leakage. Anonymous registration has two basic features, i.e. privacy and verifiability, and two extended features, i.e. traceability and revocability. We design and implement an anonymous registration scheme with the above features, named Traceable Revocable Anonymous Registration Scheme (TRARS) based on Blockchain. In the proposed registration process, the user can calculate a zero-knowledge proof for a self-generated AId, which can prove to the registration server that the AId is associated with a valid RId and the RId's attributes meet the server's requirements, without leaking any privacy. We also introduce an identity revocation coordinator, with which evil identities can be tracked and outdated AIds can be revoked timely.