Cross chain interoperability in blockchain systems exposes a fundamental tension between user privacy and regulatory accountability. Existing solutions enforce an all or nothing choice between full anonymity and mandatory identity disclosure, which limits adoption in regulated financial settings. We present VeilAudit, a cross chain auditing framework that introduces Auditor Only Linkability, which allows auditors to link transaction behaviors that originate from the same anonymous entity without learning its identity. VeilAudit achieves this with a user generated Linkable Audit Tag that embeds a zero knowledge proof to attest to its validity without exposing the user master wallet address, and with a special ciphertext that only designated auditors can test for linkage. To balance privacy and compliance, VeilAudit also supports threshold gated identity revelation under due process. VeilAudit further provides a mechanism for building reputation in pseudonymous environments, which enables applications such as cross chain credit scoring based on verifiable behavioral history. We formalize the security guarantees and develop a prototype that spans multiple EVM chains. Our evaluation shows that the framework is practical for today multichain environments.

翻译：区块链系统中的跨链互操作性暴露了用户隐私与监管可审计性之间的根本性矛盾。现有解决方案强制用户在完全匿名和强制身份披露之间做出非此即彼的选择，这限制了其在受监管金融环境中的采用。我们提出了VeilAudit，一个引入“仅审计者可关联性”的跨链审计框架，该框架允许审计者在不获知匿名实体身份的情况下，关联源自同一匿名实体的交易行为。VeilAudit通过用户生成的“可关联审计标签”实现这一点，该标签嵌入了一个零知识证明以证实其有效性，同时不暴露用户的主钱包地址；此外，还采用了一种特殊密文，只有指定的审计者才能测试其关联性。为了平衡隐私与合规性，VeilAudit还支持在正当程序下进行门限控制的身份揭示。VeilAudit进一步提供了一种在匿名环境下构建信誉的机制，从而支持基于可验证行为历史的跨链信用评分等应用。我们形式化了其安全保证，并开发了一个跨越多个EVM链的原型系统。评估结果表明，该框架适用于当今的多链环境。