Quantum Inf Process (2012) 11:373–384
New quantum private comparison protocol using EPR
Hsin-Yi Tseng · Jason Lin · Tzonelih Hwang
Received: 17 December 2010 / Accepted: 18 May 2011 / Published online: 5 June 2011
© Springer Science+Business Media, LLC 2011
Abstract Based on EPR pairs, this paper proposes a different quantum private com-
parison (QPC) protocol enabling two parties to compare the equality of their informa-
tion without revealing the information content. Due to the use of quantum entanglement
of Bell state as well as one-way quantum transmission, the new protocol provides
easier implementation as well as better qubit efﬁciency (near 50%) than the other
QPCs. It is secure against Trojan horse attack and other well-known attacks.
Keywords EPR pair · Quantum private comparison · Bell state · Qubit efﬁciency
Since the ﬁrst quantum key distribution (QKD) protocol presented by Bennett and
Brassard , many quantum cryptographic protocols, such as teleportation [6–11],
quantum secret sharing (QSS) [12–20], quantum secure direct communication (QSDC)
[21–25], and so on, have been proposed to solve various security problems. Recently,
quantum private comparison (QPC) has become an important branch of quantum
cryptography [26,27]. The main goal of a QPC is to privately compare the equality of
two parties’ information. Based on the properties of quantum mechanics, the equality
comparison can be easily achieved without any complex computation.
H.-Y. Tseng · J. Lin · T. Hwang (
Department of Computer Science and Information Engineering, National Cheng Kung University,
No. 1, University Rd., Tainan 701, Taiwan, R.O.C.