Tutorial

Abstract

Private information retrieval (PIR) is a cryptographic primitive that facilitates the seemingly impossible task of letting users fetch records from untrusted and remote database servers without revealing to those servers which records are being fetched. The research literature on PIR is vast; the over two decades since its 1995 introduction by Chor, Goldreich, Kushilevitz, and Sudan, the cryptography, privacy, and theoretical computer science research communities have studied PIR intensively and from a variety of perspectives. Alas, despite a series of significant advances, most privacy practitioners and theoreticians alike fall into one of two camps: (i) those who believe that PIR is so inefficient and abstruse as to make it all-but-useless practice, and (ii) those who remain blissfully unaware that PIR even exists. Indeed, to date not even one of the numerous PIR-based applications proposed the research literature has been deployed at scale to protect the privacy of users in the wild. This tutorial targets both of the above camps, presenting a bird's-eye overview of the current state of PIR research. Topics covered will span the spectrum from purely theoretical through imminently applicable and all the high points between, thereby providing participants with an awareness of what modern PIR techniques have (and do not have) to offer, dispelling the myth of PIR's inherent impracticality, and hopefully inspiring participants to identify practical use cases for PIR within their own niche areas of expertise. This introductory tutorial will be accessible to anyone comfortable with college-level mathematics (basic linear algebra and some elementary probability and number theory).