The Role of Coded Side Information in Single-Server Private Information Retrieval

We study the role of coded side information in single-server Private Information Retrieval (PIR). An instance PIR problem includes a server that stores database K independently and uniformly distributed messages, user who wants to retrieve one these messages from server. consider settings which initially has access linear combination subset M database. assume identities form support set as well coding coefficients are unknown two different models, depending on whether requested message or not. also following privacy requirements: (i) both demand need be protected, (ii) only identity needs protected. For each model for requirements, we designing protocol generating user's query server's answer enables decode they while satisfying requirement. characterize (scalar-linear) capacity setting, defined ratio number bits minimum downloaded over all protocols satisfy condition. Our converse proofs rely new information-theoretic arguments-tailored setting commonly-used techniques multi-server settings. present novel capacity-achieving scalar-linear being considered.