论文标题

重建攻击对差异隐私的积极放松

Reconstruction Attacks on Aggressive Relaxations of Differential Privacy

论文作者

Protivash, Prottay, Durrell, John, Ding, Zeyu, Zhang, Danfeng, Kifer, Daniel

论文摘要

差异隐私是广泛接受的正式隐私定义,允许在控制数据中出现记录的个人的隐私泄漏时发布有关数据集的汇总信息。由于隐私与实用性之间的不可避免的紧张关系,许多著作试图放松差异隐私的要求以实现更大的效用。在隐私社区之外开始获得支持的一类放松是由个人差异隐私(IDP)和引导差异隐私(BDP)的定义所体现的。差异隐私的原始版本定义了一组相邻的数据库对,并通过要求每对邻居对攻击者几乎没有区别来实现其隐私保证。但是,我们研究的隐私定义会积极地减少受保护的相邻对的集合。 IDP和BDP都定义了“隐私损失”的度量,该量度满足了正式的隐私属性,例如后处理和组成,并比传统的差异隐私变体获得了明显更好的效用。但是,有一个很大的缺点 - 我们表明,它们允许使用在其隐私会计规则下任意较低隐私损失的算法对数据集的很大一部分进行重建。我们使用这些隐私定义的首选机制证明了这些攻击。特别是,我们设计了一组查询,这些查询受到具有高噪声设置的这些机制(即具有非常低隐私损失的索赔)的保护,就会产生有关数据集的更精确信息,而不是完全没有保护。

Differential privacy is a widely accepted formal privacy definition that allows aggregate information about a dataset to be released while controlling privacy leakage for individuals whose records appear in the data. Due to the unavoidable tension between privacy and utility, there have been many works trying to relax the requirements of differential privacy to achieve greater utility. One class of relaxation, which is starting to gain support outside the privacy community is embodied by the definitions of individual differential privacy (IDP) and bootstrap differential privacy (BDP). The original version of differential privacy defines a set of neighboring database pairs and achieves its privacy guarantees by requiring that each pair of neighbors should be nearly indistinguishable to an attacker. The privacy definitions we study, however, aggressively reduce the set of neighboring pairs that are protected. Both IDP and BDP define a measure of "privacy loss" that satisfies formal privacy properties such as postprocessing invariance and composition, and achieve dramatically better utility than the traditional variants of differential privacy. However, there is a significant downside - we show that they allow a significant portion of the dataset to be reconstructed using algorithms that have arbitrarily low privacy loss under their privacy accounting rules. We demonstrate these attacks using the preferred mechanisms of these privacy definitions. In particular, we design a set of queries that, when protected by these mechanisms with high noise settings (i.e., with claims of very low privacy loss), yield more precise information about the dataset than if they were not protected at all.

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