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Masaru Fuse

Publications and source records attributed to Masaru Fuse.

2 recordsLinked to original sources
arXiv2005

Quantum stream cipher by Yuen 2000 protocol: Design and experiment by intensity modulation scheme

This paper shall investigate Yuen protocol, so called Y-00, which can realize a randomized stream cipher with high bit rate(Gbps) for long distance(several hundreds km). The randomized stream cipher with randomization by quantum noise based on Y-00 is called quantum stream cipher in this paper, and it may have security against known plaintext attacks which has no analog with any conventional symmetric key ciphers. We present a simple cryptanalysis based on an attacker's heterodyne measurement and the quantum unambiguous measurement to make clear the strength of Y-00 in real communication. In addition, we give a design for the implementation of an intensity modulation scheme and report the experimental demonstration of 1 Gbps quantum stream cipher through 20 km long transmission line.

quant-ph↗
arXiv2004

A quantum symmetric key cipher(Y-00) and key generation (Quantum stream cipher-Part II)

What obstructs the realization of useful quantum cryptography is single photon scheme, or entanglement which is not applicable to the current infrastructure of optical communication network. We are concerned with the following question: Can we realize the information theoretically secure symmetric key cipher under "the finite secret key" based on quantum-optical communications? A role of quantum information theory is to give an answer for such a question. As an answer for the question, a new quantum cryptography was proposed by H.P.Yuen, which can realize a secure symmetric key cipher with high speeds(Gbps) and for long distance(1000 Km). Although some researchers claim that Yuen protocol(Y-00) is equivalent to the classical cryptography, they are all mistaken. Indeed it has no classical analogue, and also provides a generalization even in the conventional cryptography. At present, it is proved that a basic model of Y-00 has at least the security such as $H(X|Y_E)=H(K|Y_E)=H(K)$, $H(K|Y_E,X)\sim 0$ under the average photon number per signal light pulse:$ \sim 10000$. Towards our final goal, in this paper, we clarify a role of classical randomness(secret key) and quantum randomness in Y-00, and give a rigorous quantum mechanical interpretation of the security, showing an analysis of quantum collective attack.

quant-ph↗