HTML5 Webook

17/84

that can reinforce the security of the whole system, by introducing a QKD platform suitable for needs such as black box and installing the application interface in infor-mation devices even though users do not know the details of it.In 2015, a practical use level verication test started, by transferring the QKD devices that passed verication tests under the condition of test bed. For example, Nippon Electric Company, Limited (NEC) has performed a veri-cation test for cryptographic communication of cyber threat information at the hub a “cyber security factory” somewhere in Tokyo since July 2015 [19]. It continued until the end of FY2016. Since then, the subsequent re-search and development has been performed by the quantum secure photonic network team.Toshiba has been performing a cryptography commu-nication experiment of genome analysis data using a 7-km circuit line between the Toshiba life science analysis center in Sendai city and the Tohoku University Tohoku Medical Megabank Organization since August 2015 [20] until August 2017. e key generation rate of these QKD de-vices is more than 50 times faster than that of products of venture companies abroad. e rate is about 1 Mbps for a transmission distance of 50 km using standard optical ber with an optical loss rate of 0.2 dB/km, and about several hundred kbps for transmission distance of 50 km using commercial optical ber (which averaged an optical loss rate of about 0.5 dB/km) actually constructed in the Tokyo area. On the other hand, these days, a national project lead by the University of Science and Technology of China is accomplishing infrastructure of nationwide super-highly-condential communication by constructing urban area QKD networks with 50 nodes in Beijing, Jinan, Hefei and Shanghai and constructing a QKD backbone of total length of 2000 km with 32 relay nodes [21]. Also, in the USA, Battelle announced that they had a plan to establish an inter-city QKD network of 700 km in collaboration with a venture company from Switzerland, id Quantique, and to release as open test bed for nonprot organizations [22].us, the technology of QKD has progressed to the stage of test operation under the realistic condition of urban areas or among cities. In the future, it will be necessary to improve the technology so as to construct a super-con-dential communication infrastructure by strengthening its practicability by stimulating operational experiences of a QKD platform under realistic condition and knowledge on safety evaluation. In this article, I provide a rough outline of QKD and introduce the QKD network architecture for which NICT is leading the development.2Principle of QKD operation2.1QKD protocol and its principleIn QKD, a transmitter encodes bit information of a random number sequence of 1s and 0s to appropriate quantum signals for transmission, and a receiver receives FiF1Outline of the BB84 protocol using polarization (corresponding table on bit information and base information between transmitter and receiver)1 0 1 1 0 0 1 1 0 0 1 1 1 0Selected basis signalDetection signal1 1 0 0 1 0 0 1 0Test bit1 0 1 0 1 0AliceBobcheckAlice and Bob pick up sifted key (case: Alice and Bob select same basis)Evaluation of error rateKey distillationGenerate secure key1101…Random number Selected basis Out put bit133-1 Research and Development of Quantum Key Distribution Network in NICT