A decentralized identity system that can provide users with self-sovereign digital identities to facilitate complete control over their own data is paramount to Web 3.0. The account system on blockchain is an ideal archetype for realizing Web 3.0 decentralized identity. However, a disadvantage of such completely anonymous identity system is that users can create multiple accounts without authentication to obfuscate their activities on the blockchain. In particular, the current anonymous blockchain account system cannot accurately register the social relationships and interactions between real human users, given the amorphous mappings between users and blockchain identities. This work proposes zkBID, a zero-knowledge blockchain-account-based Web 3.0 decentralized identity scheme, to overcome endemic mistrust in blockchain account systems. zkBID links souls (blockchain accounts) to humans (users' personhood credentials) in a one-to-one manner to truly reflect the social relationships and interactions between humans on the blockchain. zkBID conceals the one-to-one relationships between blockchain accounts and users' personhood credentials for privacy protection using zero-knowledge proofs and linkable ring signatures. Thus, with zkBID, the users' blockchain accounts are credibly anonymous. Importantly, zkBID is fully decentralized: all user-related data are generated by users and verified by smart contracts on the blockchain. We implemented zkBID and built a blockchain test network for evaluation purposes. Our tests demonstrate the effectiveness of zkBID and suggest proper ways to configure zkBID system parameters.

翻译：能够为用户提供自主主权数字身份、使其完全掌控自身数据的去中心化身份系统，对于Web 3.0至关重要。区块链账户系统是实现Web 3.0去中心化身份的理想原型。然而，此类完全匿名身份系统的缺陷在于，用户无需认证即可创建多个账户以混淆其在区块链上的活动。特别是，由于用户与区块链身份之间存在非结构化映射关系，当前匿名区块链账户系统无法准确记录真实人类用户间的社会关系与交互行为。为克服区块链账户系统中普遍存在的信任缺失问题，本研究提出zkBID——一种基于零知识证明的区块链账户Web 3.0去中心化身份方案。zkBID以一对一方式将灵魂（区块链账户）与人类（用户人格凭证）相连接，从而真实反映人类在区块链上的社会关系与交互行为。通过零知识证明与可链接环签名技术，zkBID隐藏了区块链账户与用户人格凭证间的一一对应关系以实现隐私保护。因此，在zkBID框架下，用户的区块链账户具有可信匿名性。值得注意的是，zkBID完全去中心化：所有用户相关数据均由用户生成，并通过区块链上的智能合约进行验证。我们实现了zkBID系统并构建了区块链测试网络进行评估。实验结果表明了zkBID的有效性，并为系统参数配置提供了合理方案。