Authors:
Hiroki Yamamuro
;
Shohei Beppu
;
Kazuhide Fukushima
and
Shinsaku Kiyomoto
Affiliation:
KDDI Research, Inc., 2-1-15 Ohara, Fujimino, Saitama, 356-8502, Japan
Keyword(s):
Quantum Key Distribution, Efficient BB84, Intercept-Resend Attack.
Abstract:
Quantum key distribution (QKD) is a secure protocol for exchanging a secret key that is based on the principles of quantum physics and fulfills information-theoretical security requirements. The first QKD protocol, BB84, was proposed in 1984. Bit information is sent via four types of quantum states, combining two types of the bits and bases in BB84. However, half of the bits are discarded after the basis information is exchanged since a sender and receiver select a basis equally likely. Lo et al. (J. Cryptol.’05) proposed Efficient BB84, in which basis selection is biased to improve the efficiency. The biased basis selection increases the probability that the selected bases match, which results in fewer bits being discarded. This letter describes an attack method against Efficient BB84 that exploits the bias in basis selection and analyzes the security of the method. An eavesdropper intercepts the first part of the quantum states, performs measurements in the basis with high selectio
n probability, and obtains bit information without being detected. We then evaluate the extent to which the obtained bit information compromises the security of the secret key.
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