Quantum Information Processing, Vol. 6, No. 2, April 2007 (© 2006)
Immunity against Correlation Attack on Quantum
Stream Cipher by Yuen 2000 Protocol
and Kaoru Kurosawa
Received April 6, 2006; accepted June 12, 2006; Published online: November 28, 2006
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 typi-
cal attack on stream ciphers. Although the security of a very simple experimental
model of the quantum stream cipher without a randomization may be reduced to
a complexity based security against the correlation attacks under a large number
of known plaintexts, it is not a basic feature of Yuen 2000 protocol. In fact, we
clarify that there exists a randomization scheme which attains the perfect correla-
tion 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 broken off also by quantum noise. In such a case, any fast
correlation attack does not work on the quantum stream cipher.
KEY WORDS: Quantum cryptography; Randomized stream cipher.
PACS: 03.67.Dd; 42.50.Lc.
The quantum stream cipher by quantum noise randomization
Yuen 2000 protocol might be an attractive new quantum cryptography
which can realize the ultra high speed data encryption. In fact, many
remarkable experiments have been demonstrated.
If this type of the
quantum cryptography can provide a pretty good security, it may be
widely applied to the real telecommunication networks. So the concrete
security analysis on the quantum stream cipher is one of the most inter-
esting subjects. In this paper, we will clarify the security property of
Research Center for Quantum Information Science, Tamagawa University, 6-1-1, Tamagawa-
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To whom correspondence should be addressed.
1570-0755/07/0400-0081/0 © 2006 Springer Science+Business Media, Inc.