Communication-efficient, Fault Tolerant PIR over Erasure Coded Storage

Private information retrieval (PIR) is a technique for a client to retrieve an item from a public database without revealing to an adversarial server the item that was queried. While multi-server PIR has been well-studied in order to obtain better communication and computation relative to single-server schemes, there are far fewer fault-tolerant PIR schemes which can remain functional even in the presence of malicious adversaries. In this paper, we present a solution that combines techniques from both the cryptography and information theory communities to design robust PIR protocols that obtain better computation, communication, and storage compared to prior state-of-the-art schemes. Our results show that our PIR protocols achieve up to 9.1× lower latency, at least 39.2× less total communication, and up to 7.3× less computation than the state-of-art robust PIR protocols for a database 4GB in size and can withstand two malicious servers, and continually outperform the robust PIR baselines for a variety of parameter configurations and failure scenarios.