arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.10174cs.ITmath.IT
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多服务器弱隐私信息检索

Multi-Server Weakly-Private Information Retrieval

Hsuan-Yin Lin, Siddhartha Kumar, Eirik Rosnes, Alexandre Graell i Amat, Eitan Yaakobi

摘要:

私有信息检索(PIR)协议确保用户可以从数据库下载文件,而不会向存储数据库的服务器泄露关于所请求文件的身份的任何信息。虽然现有的协议严格规定,没有信息泄露的文件的身份,这项工作开始研究的权衡,可以通过放松完美的隐私要求。我们将这样的协议称为弱私有信息检索(WPIR)协议。特别是,对于多个noncoluding复制服务器的情况下,我们研究了如何下载速率,上传成本,和访问的复杂性,可以改善时,放松充分的隐私约束。为了量化关于所请求文件的身份的信息泄漏,我们考虑互信息(MI)、最坏情况信息泄漏和最大泄漏(MaxL)。我们提出了两个WPIR计划,表示为方案A和方案B,基于最近的两个PIR协议,并表明前者的下载速率可以通过求解凸优化问题进行优化。我们还表明,方案A实现了改进的下载速率相比,最近提出的方案由Samy等人。根据所谓的$ε$隐私度量。此外,一个家庭的计划的基础上划分。此外,我们提供了一个信息理论上的逆界的最大可能的下载速率的MI和MaxL隐私指标的查询和答案的字母表大小的实际限制下。对于两个服务器和两个文件,在MaxL度量下,边界是紧的,这在此特定情况下确定了WPIR容量。最后,我们比较了所提出的方案的性能和他们的差距的逆界。

英文摘要:

Private information retrieval (PIR) protocols ensure that a user can download a file from a database without revealing any information on the identity of the requested file to the servers storing the database. While existing protocols strictly impose that no information is leaked on the file's identity, this work initiates the study of the tradeoffs that can be achieved by relaxing the perfect privacy requirement. We refer to such protocols as weakly-private information retrieval (WPIR) protocols. In particular, for the case of multiple noncolluding replicated servers, we study how the download rate, the upload cost, and the access complexity can be improved when relaxing the full privacy constraint. To quantify the information leakage on the requested file's identity we consider mutual information (MI), worst-case information leakage, and maximal leakage (MaxL). We present two WPIR schemes, denoted by Scheme A and Scheme B, based on two recent PIR protocols and show that the download rate of the former can be optimized by solving a convex optimization problem. We also show that Scheme A achieves an improved download rate compared to the recently proposed scheme by Samy et al. under the so-called $ε$-privacy metric. Additionally, a family of schemes based on partitioning is presented. Moreover, we provide an information-theoretic converse bound for the maximum possible download rate for the MI and MaxL privacy metrics under a practical restriction on the alphabet size of queries and answers. For two servers and two files, the bound is tight under the MaxL metric, which settles the WPIR capacity in this particular case. Finally, we compare the performance of the proposed schemes and their gap to the converse bound.

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