Practical private database queries based on a quantum key distribution protocol

TL;DR

This paper presents a practical, loss-tolerant quantum key distribution-based protocol for private database queries that offers a meaningful security level grounded in physical principles, enhancing privacy and implementation feasibility.

Contribution

It introduces a novel approach to private queries using quantum key distribution with minimal classical post-processing modifications, improving practicality and security assumptions.

Findings

Protocol is easy to implement and loss-tolerant.

Achieves a significant degree of security based on physical principles.

Potential for practical quantum private query applications.

Abstract

Private queries allow a user Alice to learn an element of a database held by a provider Bob without revealing which element she was interested in, while limiting her information about the other elements. We propose to implement private queries based on a quantum key distribution protocol, with changes only in the classical post-processing of the key. This approach makes our scheme both easy to implement and loss-tolerant. While unconditionally secure private queries are known to be impossible, we argue that an interesting degree of security can be achieved, relying on fundamental physical principles instead of unverifiable security assumptions in order to protect both user and database. We think that there is scope for such practical private queries to become another remarkable application of quantum information in the footsteps of quantum key distribution.