arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1906.09259cs.ITmath.IT
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带编码边信息的多服务器私有信息检索

Multi-Server Private Information Retrieval with Coded Side Information

Fatemeh Kazemi, Esmaeil Karimi, Anoosheh Heidarzadeh, Alex Sprintson

摘要:

在本文中,我们研究了多服务器设置的\emph{Private Information Retrieval with Coded Side Information (PIR-CSI)}问题。在这个问题中,存在跨$N$服务器复制的$K$消息,并且存在希望从服务器下载一个消息而不向任何服务器泄露关于所请求消息的身份的任何信息的用户。用户具有辅助信息,该辅助信息是数据库中$M$消息子集的线性组合。参数$M$预先为所有服务器所知,而用户侧信息中的消息的索引和系数为任何服务器\emph{a priori}所知。我们专注于一类PIR-CSI方案,称为\emph{server-symmetric schemes},其中查询/答案/从不同的服务器是对称的结构。我们将PIR-CSI方案的\emph{rate}定义为所有问题实例中的最小下载速率,并将PIR-CSI问题的\emph{server-symmetric capacity}定义为所有服务器对称PIR-CSI方案的速率上确界。我们的主要结果如下:(i)当侧信息不是用户的请求消息的函数时,对于任何${1\leq M\leq K-1}$,容量由${(1+{1}/{N}+\dots+{1}/{N^{\left\lceil \frac{K}{M+1}\right\rceil -1}})^{-1}}$给出;以及(ii)当侧信息是用户的请求消息的函数时,对于$M=2$和$M=K$,容量等于$1$,并且对于任何${3 \leq M \leq K-1}$,容量等于${N}/{(N+1)}$。逆证明依赖于新的信息理论参数,和可扩展性计划的灵感来自我们最近提出的单服务器PIR-CSI方案以及多服务器PIR的Sun-Jafar方案。

英文摘要:

In this paper, we study the multi-server setting of the \emph{Private Information Retrieval with Coded Side Information (PIR-CSI)} problem. In this problem, there are $K$ messages replicated across $N$ servers, and there is a user who wishes to download one message from the servers without revealing any information to any server about the identity of the requested message. The user has a side information which is a linear combination of a subset of $M$ messages in the database. The parameter $M$ is known to all servers in advance, whereas the indices and the coefficients of the messages in the user's side information are unknown to any server \emph{a priori}. We focus on a class of PIR-CSI schemes, referred to as \emph{server-symmetric schemes}, in which the queries/answers to/from different servers are symmetric in structure. We define the \emph{rate} of a PIR-CSI scheme as its minimum download rate among all problem instances, and define the \emph{server-symmetric capacity} of the PIR-CSI problem as the supremum of rates over all server-symmetric PIR-CSI schemes. Our main results are as follows: (i) when the side information is not a function of the user's requested message, the capacity is given by ${(1+{1}/{N}+\dots+{1}/{N^{\left\lceil \frac{K}{M+1}\right\rceil -1}})^{-1}}$ for any ${1\leq M\leq K-1}$; and (ii) when the side information is a function of the user's requested message, the capacity is equal to $1$ for $M=2$ and $M=K$, and it is equal to ${N}/{(N+1)}$ for any ${3 \leq M \leq K-1}$. The converse proofs rely on new information-theoretic arguments, and the achievability schemes are inspired by our recently proposed scheme for single-server PIR-CSI as well as the Sun-Jafar scheme for multi-server PIR.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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