We consider information leakage to the user in private information retrieval (PIR) systems. Information leakage can be measured in terms of individual message leakage or total leakage. Individual message leakage, or simply individual leakage, is defined as the amount of information that the user can obtain on any individual message that is not being requested, and the total leakage is defined as the amount of information that the user can obtain about all the other messages except the one being requested. In this work, we characterize the tradeoff between the minimum download cost and the individual leakage, and that for the total leakage, respectively. Coding schemes are proposed to achieve these optimal tradeoffs, which are also shown to be optimal in terms of the message size. We further characterize the optimal tradeoff between the minimum amount of common randomness and the total leakage. Moreover, we show that under individual leakage, common randomness is in fact unnecessary when there are more than two messages.

中文翻译：

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浅谈隐私信息检索系统中的信息泄露


我们考虑在私人信息检索（PIR）系统中向用户泄露信息。信息泄漏可以用单个消息泄漏或总体泄漏来衡量。单个消息泄漏，或简称单个泄漏，定义为用户可以获得的任何未被请求的单个消息的信息量，总泄漏定义为用户可以获得的所有消息的信息量。除所请求的消息之外的其他消息。在这项工作中，我们分别描述了最小下载成本和个体泄漏以及总泄漏之间的权衡。编码方案被提出来实现这些最佳权衡，这些方案在消息大小方面也被证明是最佳的。我们进一步描述了最小公共随机性和总泄漏之间的最佳权衡。此外，我们表明，在个体泄漏的情况下，当存在两个以上的消息时，公共随机性实际上是不必要的。