title: Hacking on decoy-state quantum key distribution system with partial phase randomization.
abstract: Quantum key distribution (QKD) provides means for unconditional secure key transmission between two distant parties. However, in practical implementations, it suffers from quantum hacking due to device imperfections. Here we propose a hybrid measurement attack, with only linear optics, homodyne detection, and single photon detection, to the widely used vacuum + weak decoy state QKD system when the phase of source is partially randomized. Our analysis shows that, in some parameter regimes, the proposed attack would result in an entanglement breaking channel but still be able to trick the legitimate users to believe they have transmitted secure keys. That is, the eavesdropper is able to steal all the key information without discovered by the users. Thus, our proposal reveals that partial phase randomization is not sufficient to guarantee the security of phase-encoding QKD systems with weak coherent states.
authors.affiliation: Department of Physics, National University of Defense Technology, Changsha 410073, P. R. China.
authors.forename: Shi-Hai
authors.initials: SH
authors.lastname: Sun
authors.affiliation: Department of Physics, National University of Defense Technology, Changsha 410073, P. R. China.
authors.forename: Mu-Sheng
authors.initials: MS
authors.lastname: Jiang
authors.affiliation: Department of Physics, National University of Defense Technology, Changsha 410073, P. R. China.
authors.forename: Xiang-Chun
authors.initials: XC
authors.lastname: Ma
authors.affiliation: Department of Physics, National University of Defense Technology, Changsha 410073, P. R. China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Li
authors.affiliation: 1] Department of Physics, National University of Defense Technology, Changsha 410073, P. R. China [2] State Key Laboratory of High Performance Computing, National University of Defense Technology, Changsha 410073, People's Republic of China.
authors.forename: Lin-Mei
authors.initials: LM
authors.lastname: Liang
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