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Quantum stream cipher based on optical communications

Hirota, O, Kato, K, Sohma, M, Usuda, T S, Harasawa, K

Published Jan 1, 2004• 8 citations
OpenAlex

Abstract

In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:$<n> = 1000 \\sim 10000$. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has $H(K) << H(X)$. In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the advantage distillation by scheme consisting of intensity modulation/direct detection optical communication.

Related papers

Quantum stream cipher based on optical communications

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In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse: <n> = 1000 ~ 10000. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has H(K)<<H(X). This is a challenge to overcome Shannon limit in the cryptography theory. In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the scheme consisting of intensity modulation/direct detection optical communication.

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In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:<n>=1000sim10000<n> = 1000 \\sim 10000<n>=1000sim10000. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has H(K)<<H(X)H(K) << H(X)H(K)<<H(X). In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the advantage distillation by scheme consisting of intensity modulation/direct detection optical communication.
In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse: <n> = 1000 ~ 10000. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has H(K)<<H(X). This is a challenge to overcome Shannon limit in the cryptography theory. In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the scheme consisting of intensity modulation/direct detection optical communication.
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-OO) is equivalent to the classical cryptography they arc 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-OO has at least the security such as H(X/YE)=H(K/YE)=H(K), H(K/YE,X)~0 under the average photon number per signal light pulse:<n>~10000. Towards our final goal in this paper we clarify a role of classical randomness(secret key) and quantum randomness in Y-OO and give a rigorous quantum mechanical interpretation of the security showing an analysis of quantum collective attack.
We investigate the Yuen 2000 (so-called Y-00)-protocol, which can realize a randomized stream cipher with high bit rate (Gbit/s) for long distances (several hundreds km). The randomized stream cipher with randomization by quantum noise based on the Y-00 protocol is called a 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 a quantum unambiguous measurement to make clear the strength of the Y-00 protocol in real communication. In addition, we give a design for the implementation of an intensity-modulation scheme and report an experimental demonstration of 1Gbit∕s1\phantom{\rule{0.3em}{0ex}}\mathrm{Gbit}∕\mathrm{s}1Gbit∕s quantum stream cipher through a $20\text{\ensuremath{-}}\mathrm{km}$-long transmission line.
The security in the next generation optical network which realizes "Cloud Computing System Service with data center" is one of the most important problems. In such a network, the encryption in physical layer which provide super security and small delay is a preferable. It has to be applicable, however, to very high speed data because the basic link is operated at 2.5 Gbit/sec ~ 10 Gbit/sec. The quantum stream cipher by Yuen-2000 protocol (Y00) is a completely new type of random cipher, which can exceed the Shannon limit of the symmetric key cipher. This paper extends some theoretical results on the security for quantum stream cipher such as Y00 protocol and generalized Y00. First, the conditions to exceed the Shannon limit are summarized. We formulate a generalized secret capacity in the sense of wire tap channel supported by secret key to clarify a cipher exceeding the Shannon limit. The generalized secret capacities for space communication and fiber communication based on the generalized Y00 are given. When the relaxation of physical constraint or device limit of the eavesdropper is allowed, we point out that a cipher scheme exceeding the Shannon limit can be realized only by the conventional optical system.
This paper is concerned with the intensity modulation-based quantum stream cipher by Yuen 2000 protocol with a nonlinear pseudorandom number generator. First we show the minimum error probability of the basic model of the intensity modulation-based quantum stream cipher in cases of ciphertext-only attacks and known plaintext attack, by using the quantum signal detection theory. Second we propose the intensity modulation-based quantum stream cipher having a nonlinear pseudorandom number generator that is realized by the basis converter. We compare the error profile of the system having the nonlinear pseudorandom number generator with that of the basic model. As a result we will see that the use of the nonlinear pseudorandom number generator yields an advantage to the legitimate users.
This paper is the part-II of the previous paper and introduces the world of Yuen's concept. In the theory of cryptology, the Shannon impossibility theorem states that the upper bound of the security of a plaintext against a ciphertext-only attack is the entropy of the secret key. At the same time, it gives the upper bound of the unicity distance against a known plaintext attack. Hence the development of a new symmetric key cipher requires finding a way to undo or lift this theorem. Such challenges have been attempted with quantum stream cipher and quantum data locking as block cipher. Both ciphers are designed by means of differentiating the receiving performance of Bob with key and Eve without key according to the principle of quantum communication theory. Thus, the origin of security of both ciphers come from the principle of keyed communication in quantum noise (KCQ) proposed by Yuen. In this paper, we explain and compare the principles and features of both cipher and assist to improve the quantum data locking scheme. Then we will introduce experimental research on quantum stream cipher towards commercialization, which has performance superior to conventional cipher.