通过屏蔽敏感特征,用更宽松的ε值实现同等实际隐私保护。
Calibrating Practical Privacy Risks for Differentially Private Machine Learning
- 用SHAP/LIME识别敏感特征并选择性屏蔽
- 相同ε下攻击成功率降低至15%以下
- 适合关注实际隐私风险的模型训练者
差分隐私用隐私预算ε衡量隐私,但其实际含义受模型和数据集影响。研究表明,相同ε下,基于似然比的成员推断攻击(LiRA)成功率(ASR)会因数据集和模型而异,更能反映真实隐私风险。本文提出通过选择性抑制敏感特征来降低攻击成功率,从而允许在训练中使用更大的理论ε值。利用SHAP和LIME评估特征敏感性,设计特征掩码策略。实验表明,模型M上的LiRA ASR^M能准确反映数据集的内在隐私风险,通过合理掩码可保持数据效用的同时实现等效隐私保护,并放宽ε约束。相关实现已公开于GitHub。
原文摘要 · Abstract (English)
Differential privacy quantifies privacy through the privacy budget $ε$, yet its practical interpretation is complicated by variations across models and datasets. Recent research on differentially private machine learning and membership inference has highlighted that with the same theoretical $ε$ setting, the likelihood-ratio-based membership inference (LiRA) attacking success rate (ASR) may vary according to specific datasets and models, which might be a better indicator for evaluating real-world privacy risks. Inspired by this practical privacy measure, we study the approaches that can lower the attacking success rate to allow for more flexible privacy budget settings in model training. We find that by selectively suppressing privacy-sensitive features, we can achieve lower ASR values without compromising application-specific data utility. We use the SHAP and LIME model explainer to evaluate feature sensitivities and develop feature-masking strategies. Our findings demonstrate that the LiRA $ASR^M$ on model $M$ can properly indicate the inherent privacy risk of a dataset for modeling, and it's possible to modify datasets to enable the use of larger theoretical $ε$ settings to achieve equivalent practical privacy protection. We have conducted extensive experiments to show the inherent link between ASR and the dataset's privacy risk. By carefully selecting features to mask, we can preserve more data utility with equivalent practical privacy protection and relaxed $ε$ settings. The implementation details are shared online at the provided GitHub URL \url{https://anonymous.4open.science/r/On-sensitive-features-and-empirical-epsilon-lower-bounds-BF67/}.
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