Quantum Inf Process (2014) 13:573–585
Comment on “efﬁcient and feasible quantum private
comparison of equality against the collective amplitude
Yi-Hua Zhou · Wei-Min Shi · Yu-Guang Yang
Received: 18 December 2012 / Accepted: 28 October 2013 / Published online: 9 November 2013
© Springer Science+Business Media New York 2013
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.
Keywords Secure multiparty quantum computation · Quantum private comparison·
single photons · Quantum cryptography
People often have to make important decisions that should remain as their secrets.
Protecting the privacy of messages that is intelligible only for the two legitimated
parties is a challenging problem. Secure multiparty computation (SMC) that allows
a group of mutually distrustful players to perform correct, distributed computations
without leaking their respective secret inputs is an efﬁcient method to deal with this
Y.-H. Zhou (
) · W.-M. Shi · Y. - G . Ya n g
College of Computer Science and Technology, Beijing University of Technology,
Beijing 100124, China
e-mail: firstname.lastname@example.org; email@example.com