SLVC-DIDA: Signature-less Verifiable Credential-based Issuer-hiding and Multi-party Authentication for Decentralized Identity

Abstract: As an emerging paradigm in digital identity, Decentralized Identity (DID) appears advantages over traditional identity management methods in a variety of aspects, e.g., enhancing user-centric online services and ensuring complete user autonomy and control. Verifiable Credential (VC) techniques are used to facilitate decentralized DID-based access control across multiple entities. However, existing DID schemes generally rely on a distributed public key infrastructure that also causes challenges, such as context information deduction, key exposure, and issuer data leakage. To address the issues above, this paper proposes a Permanent Issuer-Hiding (PIH)-based DID multi-party authentication framework with a signature-less VC model, named SLVC-DIDA, for the first time. Our proposed scheme avoids the dependence on signing keys by employing hashing and issuer membership proofs, which supports universal zero-knowledge multi-party DID authentications, eliminating additional technical integrations. We adopt a zero-knowledge RSA accumulator to maintain the anonymity of the issuer set, thereby enabling public verification while safeguarding the privacy of identity attributes via a Merkle tree-based VC list. By eliminating reliance on a Public Key Infrastructure (PKI), SLVC-DIDA enables fully decentralized issuance and verification of DIDs. Furthermore, our scheme ensures PIH through the implementation of the zero-knowledge Issuer set and VC list, so that the risks of key leakage and contextual inference attacks are effectively mitigated. Our experiments further evaluate the effectiveness and practicality of SLVC-DIDA.