Comment on “efficient and feasible quantum private comparison of equality against the collective amplitude damping noise”

Abstract

In this paper, protocols of quantum private comparison of equality (QPCE) are investigated. We study the security of previous QPCE protocols with a semi-honest third party (TP) from the viewpoint of secure multiparty computation and show that QPCE protocol (Chen et al. Quantum Inf Process 2012) has an obvious security flaw. A vicious inside attacker impersonating TP or the compromised TP colluding with a dishonest inside player can steal other player's secret successfully. An improved efficient and feasible QPCE protocol is proposed. In our improved scheme, only the two players can deduce the results of comparisons based on their shared key, and others will learn no information of the comparison results, even the length of secrets. The cost of communication is also be optimized. Our scheme can resist various kinds of attacks from both the outside eavesdroppers and the inside players, even the TP.