Physics – Quantum Physics
Scientific paper
2003-09-17
Quantum Information and Computation. Vol. 5, No.1 (2005) 40-47.
Physics
Quantum Physics
Replaced with revised version. 8 pages. No figure. Abstract truncated because of the 24-line limit in quant-ph
Scientific paper
Quantum-based cryptographic protocols are often said to enjoy security guaranteed by the fundamental laws of physics. However, even carefully designed quantum-based cryptographic schemes may be susceptible to subtle attacks that are outside the original design. As an example, we give attacks against a recently proposed ``secure communication using mesoscopic coherent states'', which employs mesoscopic states, rather than single-photon states. Our attacks can be used either as a known-plaintext attack or in the case where the plaintext has not been randomized. One of our attacks requires beamsplitters and the replacement of a lossy channel by a lossless one. It is successful provided that the original loss in the channel is so big that Eve can obtain 2^k copies of what Bob receives, where k is the length of the seed key pre-shared by Alice and Bob. Substantial improvements over such an exhaustive key search attack can be made, whenever a key is reused. Furthermore, we remark that, under the same assumption of a known or non-random plaintext, Grover's exhaustive key search attack can be applied directly to "secure communication using mesoscopic coherent states", whenever the channel loss is more than 50 percent. Therefore, as far as information-theoretic security is concerned, optically amplified signals necessarily degrade the security of the proposed scheme, when the plaintext is known or non-random. Our attacks apply even if the mesoscopic scheme is used only for key generation with a subsequent use of the key for one-time-pad encryption.
Ko Tsz-Mei
Lo Hoi-Kwong
No associations
LandOfFree
Some Attacks On Quantum-based Cryptographic Protocols does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Some Attacks On Quantum-based Cryptographic Protocols, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Some Attacks On Quantum-based Cryptographic Protocols will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-137902