Performing private database queries in a real-world environment using a quantum protocol

TL;DR

This paper introduces a fault-tolerant quantum private query protocol that incorporates error correction, enabling practical and secure database queries over noisy channels, demonstrated through a fiber-optic implementation.

Contribution

It presents the first fault-tolerant quantum private query protocol with integrated error correction, suitable for real-world noisy environments.

Findings

Protocol is secure against noise and errors.

Successful demonstration over deployed fiber.

Error correction is crucial for security.

Abstract

In the well-studied cryptographic primitive 1-out-of-N oblivious transfer, a user retrieves a single element from a database of size N without the database learning which element was retrieved. While it has previously been shown that a secure implementation of 1-out-of-N oblivious transfer is impossible against arbitrarily powerful adversaries, recent research has revealed an interesting class of private query protocols based on quantum mechanics in a cheat sensitive model. Specifically, a practical protocol does not need to guarantee that database cannot learn what element was retrieved if doing so carries the risk of detection. The latter is sufficient motivation to keep a database provider honest. However, none of the previously proposed protocols could cope with noisy channels. Here we present a fault-tolerant private query protocol, in which the novel error correction procedure is integral to the security of the protocol. Furthermore, we present a proof-of-concept demonstration of the protocol over a deployed fibre.