Threshold quantum secure direct communication without entanglement

For the first time, a threshold quantum secure direct communication (TQSDC) scheme is presented. Similar to the classical Shamir's secret sharing scheme, the sender makes n shares, S1, …, Sn of secret key K and each receiver keeps a share secretly. If the sender wants to send a secret message M to the receivers, he en-codes the information of K and M on a single photon sequence and sends it to one of the receivers. According to the secret shares, the t receivers sequentially per-form the corresponding unitary operations on the single photon sequence and ob-tain the secret message M. The shared shares may be reusable if it can be judged that there is no eavesdropper in line. We discuss that our protocol is feasible with current technology.

Threshold quantum secure direct communication without entanglement

For the first time, a threshold quantum secure direct communication (TQSDC) scheme is presented. Similar to the classical Shamir’s secret sharing scheme, the sender makes n shares, S ₁, ..., S _n of secret key K and each receiver keeps a share secretly. If the sender wants to send a secret message M to the receivers, he encodes the information of K and M on a single photon sequence and sends it to one of the receivers. According to the secret shares, the t receivers sequentially perform the corresponding unitary operations on the single photon sequence and obtain the secret message M. The shared shares may be reusable if it can be judged that there is no eavesdropper in line. We discuss that our protocol is feasible with current technology. Supported by the National Basic Research Program of China (973 Program) (Grant No. 2007CB311100), the National High Technology Research and Development Program of China (Grant Nos. 2006AA01Z419 and 20060101Z4015), the Major Research Plan of the National Natural Science Foundation of China (Grant No. 90604023), the 2008 Scientific Research Common Program of Beijing Municipal Commission of Education; the Scientific Research Foundation for the Youth of Beijing University of Technology (Grant No. 97007016200701), the National Research Foundation for the Doctoral Program of Higher Education of China (Grant No. 20040013007), the National Laboratory for Modern Communications Science Foundation of China (Grants No. 9140C1101010601), the Doctor Scientific Research Activation Foundation of Beijing University of Technology (No. 52007016200702), and the Open Foundation of State Key Laboratory of Information Security (Graduate School of the Chinese Academy of Sciences)