Unconditional Security in Cryptography

Yu‐Fang Chung, Zhen Yu Wu, Tzer‐Shyong Chen

Chiara Macchiavello, Anna Sanpera

Jai Wan Cho, Young Soo Choi, Jae Chul Lee +5 more

Quantum cryptography communication based on quantum mechanics provides and unconditional security between two users. Even though huge advance has been done since the 1984, having a complete system is still far away. In the case of real quantum cryptography communication systems, an unconditional security level is lowered by the imperfection of the communication unit. It is important to investigate the unconditional security of quantum communication protocols based on these experimental results and implementation examples for the advanced spread all over the world. The Japanese report, titled, 'Investigation report on the worldwide trends of quantum cryptography communications systems' was translated and summarized in this report. An unconditional security theory of the quantum cryptography and real implementation examples in the domestic area are investigated also. The goal of the report is to make quantum cryptography communication more useful and reliable alternative telecommunication infrastructure as the one of the cyber security program of the class 1-E communication system of nuclear power plant. Also another goal of this report is to provide the quantitative decision basis on the quantum cryptography communication when this secure communication system will be used in class 1-E communication channel of the nuclear power plant.

Yong Wang

Carlo Ottaviani, Stefano Pirandola

In first place we analysed the security of two-way QKD against coherent attacks achieving unconditional security in all encoding/decoding configurations. In second place we studied the security, at different wavelengths, of two-way thermal QKD finding a robust threshold in reverse reconciliation, improving the security distances for continuous variable quantum cryptography in the infrared.