arXiv:2607.21839cs.CRcs.LG2026-07

现有加密模型认证方法在真实场景中可能失效,作者提出新安全定义和通用协议解决此问题。

Certified in Theory, Broken in Practice: Assumption Gaps in Cryptographic Model Certification

论文配图:Certified in Theory, Broken in Practice: Assumption Gaps in Cryptographic Model Certification
图 1 · 摘自论文原文
  • 提出针对模型认证的严格安全定义,要求保证跨数据集泛化能力
  • 实验证明攻击者可在审计时显示99%准确率,实际部署后降至30%以下
  • 设计通用协议模板,支持隐私保护且具备真实世界可信保障

隐私保护机器学习审计协议使审计员可在不暴露模型内部结构或训练数据的前提下评估模型的准确性或公平性等属性,适用于医疗、金融等敏感领域。然而,现有安全定义通常仅保证模型在固定审计数据集上的行为,无法确保这些保证能推广到同分布下的其他数据集。本文揭示,这导致攻击者可精心构造训练数据,使模型在审计时表现良好,但实际部署时出现异常行为。例如,实验表明模型可在审计集上达到99%准确率,但在来自相同分布的新样本上准确率低于30%。为填补这一差距,本文形式化了适用于加密模型认证(CMC)框架的严格密码学安全概念,提出一个通用协议模板,并证明其满足这些要求。研究既警示了现有方法的脆弱性,也为构建真正安全的隐私保护机器学习审计协议提供了可行路径。

原文摘要 · Abstract (English)

Privacy-preserving machine learning auditing protocols allow auditors to assess models for properties such as accuracy or fairness, without revealing their internals or training data. This makes them especially attractive for auditing models deployed in sensitive domains such as healthcare or finance. For these protocols to be meaningful in real-world audit settings, though, their guarantees must reflect how the model will behave once deployed, rather than merely certifying its behavior during an audit. Existing security definitions often miss this mark: most certify model behavior only on a fixed audit dataset, without ensuring that the same guarantees generalize to other datasets drawn from the same distribution. As we show, this gap allows a model provider to attack many cryptographic model certification (CMC) schemes built on secure zero knowledge proofs (ZKP) by carefully engineering training data, resulting in models that exhibit benign behavior during an audit, but pathological behavior in practice. For example, we empirically demonstrate that an attacker can certify that a model achieves over 99% accuracy on an audit dataset, but less than 30% accuracy on fresh samples from the same distribution. To address this gap, we formalize rigorous cryptographic security notions tailored to CMC frameworks, introduce a generic protocol template, and prove that it satisfies these requirements. Our results thus offer both cautionary evidence about existing approaches and constructive guidance for designing secure, privacy-preserving ML auditing protocols.

模型审计加密认证隐私保护安全漏洞

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