Paper 2026/1135 Original: eprint.iacr.org/2026/1135 ↗

Private Information Retrieval: A Tutorial and Survey

Abstract

Private information retrieval (PIR) is a fundamental primitive for protecting user privacy. It enables a user to retrieve entries from a public database without revealing which entries are being retrieved. PIR has been studied in many settings, e.g., with information-theoretic or computational security, with a single server or multiple non-colluding servers, and with or without preprocessing to the database. In this article, we describe several PIR schemes that we believe are accessible to readers without prior knowledge in PIR. Although conceptually simple, these schemes capture the main ideas underlying mainstream design paradigms. We also describe extensions of PIR that support keyword queries and batch queries. Beyond describing the schemes themselves, we characterize the concrete efficiency of different PIR paradigms, provide guidance on selecting a paradigm in practice, and discuss practical applications of PIR. We hope this article helps readers understand the current research landscape in PIR and serves as a starting point for exploring more advanced topics in the field.