Private information retrieval with preprocessing based on the approximate GCD problem

Abstract

PIR protocols allow clients to privately recover data on a server. While many protocols exist, none of them are practical due to their high computation requirement. We explain how preprocessing is a necessity to solve this issue, then we present two independent but related results. First, we show how Goldberg’s robust multi-server PIR protocol is compatible with preprocessing techniques. We detail the theoretical computation/memory tradeoff and present practical implementation results. Then, we introduce a new single-server PIR protocol that is reminiscent of Goldberg’s protocol in its structure but relies on the unrelated Approximate GCD assumption. We describe its performance and security, along with implementation results.