This paper presents the security analysis on the quantum stream cipher so called Yuen-2000 protocol (or $αη$ scheme) against the fast correlation attack, the typical attack on stream ciphers. Although a very simple experimental model of the quantum stream cipher without a random mapper may be decrypted in the information theoretic sense by the fast correlation algorithm, it is not a basic feature of Yuen 2000 protocol. In fact, we clarify that there exists a randomization scheme which attains the perfect correlation immunity against such attacks under an approximation. And in this scheme, the running key correlation from the second randomization that determines the mapping patterns is dismissed also by quantum noise. In such a case, any fast correlation attack does not work on the quantum stream cipher.This paper presents the security analysis on the quantum stream cipher so called Yuen-2000 protocol (or $αη$ scheme) against the fast correlation attack, the typical attack on stream ciphers. Although a very simple experimental model of the quantum stream cipher without a random mapper may be decrypted in the information theoretic sense by the fast correlation algorithm, it is not a basic feature of Yuen 2000 protocol. In fact, we clarify that there exists a randomization scheme which attains the perfect correlation immunity against such attacks under an approximation. And in this scheme, the running key correlation from the second randomization that determines the mapping patterns is dismissed also by quantum noise. In such a case, any fast correlation attack does not work on the quantum stream cipher.

arXiv:quant-ph/0604036Apr 6, 20061 citation

Quantum-noise randomized ciphers

Ranjith Nair, Horace P. Yuen, Eric Corndorf +2 more

We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as $\ensuremath{\alpha}\ensuremath{\eta}$ and show that it is equivalent to a random cipher in which the required randomization is affected by coherent-state quantum noise. We describe the currently known security features of $\ensuremath{\alpha}\ensuremath{\eta}$ and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext attacks. We show how $\ensuremath{\alpha}\ensuremath{\eta}$ used in conjunction with any standard stream cipher such as the Advanced Encryption Standard provides an additional, qualitatively different layer of security from physical encryption against known-plaintext attacks on the key. We refute some claims in the literature that $\ensuremath{\alpha}\ensuremath{\eta}$ is equivalent to a nonrandom stream cipher.We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as $\ensuremath{\alpha}\ensuremath{\eta}$ and show that it is equivalent to a random cipher in which the required randomization is affected by coherent-state quantum noise. We describe the currently known security features of $\ensuremath{\alpha}\ensuremath{\eta}$ and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext attacks. We show how $\ensuremath{\alpha}\ensuremath{\eta}$ used in conjunction with any standard stream cipher such as the Advanced Encryption Standard provides an additional, qualitatively different layer of security from physical encryption against known-plaintext attacks on the key. We refute some claims in the literature that $\ensuremath{\alpha}\ensuremath{\eta}$ is equivalent to a nonrandom stream cipher.

arXiv:quant-ph/0603263Physical Review ANov 7, 200661 citations

Randomization techniques for the intensity modulation-based quantum stream cipher and progress of experiment

Kentaro Kato, Osamu Hirota

The quantum noise based direct encryption protocol Y-OO is expected to provide physical complexity based security, which is thought to be comparable to information theoretic security in mathematical cryptography, for the. physical layer of fiber-optic communication systems. So far, several randomization techniques for the quantum stream cipher by Y-OO protocol have been proposed, but most of them were developed under the assumption that phase shift keying is used as the modulation format. On the other hand, the recent progress in the experimental study on the intensity modulation based quantum stream cipher by Y-OO protocol raises expectations for its realization. The purpose of this paper is to present design and implementation methods of a composite model of the intensity modulation based quantum stream cipher with some randomization techniques. As a result this paper gives a viewpoint of how the Y-OO cryptosystem is miniaturized.The quantum noise based direct encryption protocol Y-OO is expected to provide physical complexity based security, which is thought to be comparable to information theoretic security in mathematical cryptography, for the. physical layer of fiber-optic communication systems. So far, several randomization techniques for the quantum stream cipher by Y-OO protocol have been proposed, but most of them were developed under the assumption that phase shift keying is used as the modulation format. On the other hand, the recent progress in the experimental study on the intensity modulation based quantum stream cipher by Y-OO protocol raises expectations for its realization. The purpose of this paper is to present design and implementation methods of a composite model of the intensity modulation based quantum stream cipher with some randomization techniques. As a result this paper gives a viewpoint of how the Y-OO cryptosystem is miniaturized.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIESep 1, 201114 citations

This paper presents the security analysis on the quantum stream cipher so called Yuen-2000 protocol (or

αη

scheme) against the fast correlation attack, the typical attack on stream ciphers. Although a very simple experimental model of the quantum stream cipher without a random mapper may be decrypted in the information theoretic sense by the fast correlation algorithm, it is not a basic feature of Yuen 2000 protocol. In fact, we clarify that there exists a randomization scheme which attains the perfect correlation immunity against such attacks under an approximation. And in this scheme, the running key correlation from the second randomization that determines the mapping patterns is dismissed also by quantum noise. In such a case, any fast correlation attack does not work on the quantum stream cipher.