基于图存储的弱隐私信息检索
Weak Private Information Retrieval for Graph-based Storage
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中文总结 AI 辅助
研究基于图存储的弱隐私信息检索问题，提出任意图的G-WPIR方案，确定其在不同泄露度量下速率与隐私的权衡，采用最小子分组化和简单概率查询实现平滑权衡，并扩展到特殊图确定相应权衡。
中文摘要 AI 辅助
基于图复制的分布式存储系统由数据库及其包含的文件组成。数据库为图的顶点，文件由边表示。在此系统上的隐私信息检索（G-PIR）旨在让客户端通过查询响应协议检索所需文件，同时不向任何数据库泄露所需文件索引的身份。G-PIR目标是在隐私约束下最大化速率。以往工作涉及完美信息理论隐私，若放松隐私约束，可设计更高速率的PIR协议，即基于图的弱隐私信息检索（G-WPIR）协议。本文提出任意图的G-WPIR方案，确定其在互信息泄露和最大泄露两种度量下速率与隐私的权衡。协议采用最小子分组化并通过简单概率查询实现平滑权衡，还扩展到完全图和完全二分图两类特殊图并确定相应权衡。
英文摘要
A distributed storage system with graph-based replication consists of a collection of databases and the files they contain. The databases (or servers) are represented as the vertices of a graph, while each file is stored in a distinct pair of servers and is represented by an edge of this graph. Private information retrieval (G-PIR) on such a graph-based storage system involves a client which seeks to retrieve a desired file via a query-response protocol, without leaking the identity of the desired file index to any database. The goal of G-PIR is to maximize the rate (reciprocal of the total normalized download) under the privacy constraint. Prior work on G-PIR has involved perfect information-theoretic privacy (i.e., null leakage). However, if the privacy constraint is relaxed, then PIR protocols could be designed that have even higher rates. We term such protocols as Graph-based Weak Private Information Retrieval (G-WPIR) protocols and initiate their formal study in this work. We propose a G-WPIR scheme for arbitrary graphs, and identify the trade-offs it achieves between rate and privacy, under two well known leakage metrics: mutual information leakage and maximal leakage. Our protocol employs minimal subpacketization (representing a file-size constraint) and employs a simple probabilistic query realization to obtain the smooth trade-off. We extend this protocol with some modifications to two special classes of graphs, the complete graphs and the complete bipartite graphs, and identify the corresponding rate-privacy trade-offs achieved.
