Pervasive Vulnerability Analysis and Defense for QKD-based Quantum Private Query

TL;DR

This paper identifies security vulnerabilities in QKD-based Quantum Private Query protocols, especially in post-processing, and proposes a multi-encryption defense scheme to enhance their security against various attacks.

Contribution

It reveals overlooked vulnerabilities in existing QKD-based QPQ protocols and introduces a multi-encryption defense strategy to improve their security against information leakage attacks.

Findings

Direct observation attack causes information leakage

Minimum error discrimination attack steals database information

Multi-encryption scheme effectively defends against these attacks

Abstract

Quantum Private Query (QPQ) based on Quantum Key Distribution (QKD) is among the most practically viable quantum communication protocols, with application value second only to QKD itself. However, prevalent security vulnerabilities in the post-processing stages of most existing QKD-based QPQ protocols have been severely overlooked. This study focuses on hidden information extraction under undetermined signal bits, revealing that most such QPQ protocols face severe security threats even without complex quantum resources. Specifically, direct observation attack causes incremental information leakage, while the minimum error discrimination attack efficiently steals additional database inforamtion. To address these critical flaws, the proposed multi-encryption defense scheme is compatible with existing QPQ protocols. The study demonstrates the necessity of the multi-encryption strategy for the security of databases in QPQ, providing key theoretical and technical support for constructing practical QPQ protocols resistant to real-world attacks.