Cryptanalysis and improvement of a semi-quantum private comparison protocol based on Bell states

TL;DR

This paper analyzes a semi-quantum private comparison protocol based on Bell states, revealing vulnerabilities to attacks and proposing improvements to enhance security against malicious parties and eavesdroppers.

Contribution

The paper identifies specific security flaws in Jiang's SQPC protocol and introduces an improved version that resists these identified attacks.

Findings

Two attack types can compromise Jiang's protocol without detection.

An improved protocol resists both external eavesdropping and malicious insider attacks.

The improved protocol enhances the security of semi-quantum private comparison methods.

Abstract

Semi-quantum private comparison (SQPC) allows two participants with limited quantum ability to securely compare the equality of their secrets with the help of a semi-dishonest third party (TP). Recently, Jiang proposed a SQPC protocol based on Bell states (Quantum Inf Process 19(6): 180, 2020) and claimed it is secure. In this paper, we present two types of attack on Jiang's SQPC protocol. In the first type of attack, an outside eavesdropper will make participants accept a wrong result. In the second type of attack, a malicious participant will not only make the other participant accept a wrong result, but also learn the secret of the honest participant. Neither type of attack will be detected. In addition, we propose an improved SQPC protocol that can resist these two types of attack.