Hierarchical Cache-Aided Linear Function Retrieval with Security and Privacy Constraints

TL;DR

This paper introduces a new hierarchical caching scheme for linear function retrieval that ensures security and privacy, optimizing data transmission and subpacketization in multi-layer caching networks.

Contribution

It proposes the hierarchical placement delivery array (HPDA) and constructs two classes of schemes addressing security, privacy, and efficiency in hierarchical caching systems.

Findings

Achieves optimal transmission load for the first hop without security constraints.

Provides a flexible scheme with lower subpacketization and a tradeoff between load and subpacketization.

Ensures content security and demand privacy in hierarchical caching.

Abstract

The hierarchical caching system where a server connects with multiple mirror sites, each connecting with a distinct set of users, and both the mirror sites and users are equipped with caching memories has been widely studied. However all the existing works focus on single file retrieval, i.e., each user requests one file, and ignore the security and privacy threats in communications. In this paper we investigate the linear function retrieval problem for hierarchical caching systems with content security and demand privacy, i.e., each user requests a linear combination of files, and meanwhile the files in the library are protected against wiretappers and users' demands are kept unknown to other users and unconnected mirror sites. First we propose a new combination structure named hierarchical placement delivery array (HPDA), which characterizes the data placement and delivery strategy of a coded caching scheme. Then we construct two classes of HPDAs. Consequently two classes of schemes with or without security and privacy are obtained respectively where the first dedicates to minimizing the transmission load for the first hop and can achieve the optimal transmission load for the first hop if ignoring the security and privacy constraints; the second has more flexible parameters on the memory sizes and a lower subpacketization compared with the first one, and achieves a tradeoff between subpacketization and transmission loads.