Cryptanalysis of a multi-party quantum key agreement protocol with single particles

Abstract

Recently, Sun et al. (Quantum Inf Process 12:3411-3420, 2013) presented an efficient multi-party quantum key agreement (QKA) protocol by employing single particles and unitary operations. The aim of this protocol is to fairly and securely negotiate a secret session key among N parties with a high qubit efficiency. In addition, the authors claimed that no participant can learn anything more than his/her prescribed output in this protocol, i.e.; the sub-secret keys of the participants can be kept secret during the protocol. However, here we point out that the sub-secret of a participant in Sun et al.'s protocol can be eavesdropped by the two participants next to him/her. Moreover, a certain number of dishonest participants can fully determine the final shared key in this protocol. Finally, we discuss the factors that should be considered when designing a really fair and secure QKA protocol. © 2014 Springer Science+Business Media New York.Recently, Sun et al. (Quantum Inf Process 12:3411-3420, 2013) presented an efficient multi-party quantum key agreement (QKA) protocol by employing single particles and unitary operations. The aim of this protocol is to fairly and securely negotiate a secret session key among N parties with a high qubit efficiency. In addition, the authors claimed that no participant can learn anything more than his/her prescribed output in this protocol, i.e.; the sub-secret keys of the participants can be kept secret during the protocol. However, here we point out that the sub-secret of a participant in Sun et al.'s protocol can be eavesdropped by the two participants next to him/her. Moreover, a certain number of dishonest participants can fully determine the final shared key in this protocol. Finally, we discuss the factors that should be considered when designing a really fair and secure QKA protocol. © 2014 Springer Science+Business Media New York