Cryptanalysis and improvement of Wu-Cai-Wu-Zhang's quantum private comparison protocol

TL;DR

This paper critically analyzes a recent quantum private comparison protocol, reveals its security flaws, and proposes an improved version that enhances security, reduces resource requirements, and increases feasibility.

Contribution

The paper identifies security issues in a recent protocol and introduces an improved version that eliminates entanglement and quantum memory needs while reducing information leakage.

Findings

The original protocol leaks more information than previously thought.

The improved protocol requires no entanglement or quantum memory.

The new protocol offers enhanced security and practicality.

Abstract

In a recent paper (Int. J. Quantum Inf. 17 (2019) 1950026), the authors discussed the shortcomings in the security of a quantum private comparison protocol that we previously proposed (Int. J. Quantum Inf. 15 (2017) 1750014). They also proposed a new protocol aimed to avoid these problems. Here we analysis the information leaked in their protocol, and find that it is even less secure than our protocol in certain cases. We further propose an improved version which has the following advantages: (1) no entanglement needed, (2) quantum memory is no longer required, and (3) less information leaked. Therefore, better security and great feasibility are both achieved.