4,410 research outputs found
Experimental implementation of non-Gaussian attacks on a continuous-variable quantum key distribution system
An intercept-resend attack on a continuous-variable quantum-key-distribution
protocol is investigated experimentally. By varying the interception fraction,
one can implement a family of attacks where the eavesdropper totally controls
the channel parameters. In general, such attacks add excess noise in the
channel, and may also result in non-Gaussian output distributions. We implement
and characterize the measurements needed to detect these attacks, and evaluate
experimentally the information rates available to the legitimate users and the
eavesdropper. The results are consistent with the optimality of Gaussian
attacks resulting from the security proofs.Comment: 4 pages, 5 figure
Complete elimination of information leakage in continuous-variable quantum communication channels
In all lossy communication channels realized to date, information is
inevitably leaked to a potential eavesdropper. Here we present a communication
protocol that does not allow for any information leakage to a potential
eavesdropper in a purely lossy channel. By encoding information into a
restricted Gaussian alphabet of squeezed states we show, both theoretically and
experimentally, that the Holevo information between the eavesdropper and the
intended recipient can be exactly zero in a purely lossy channel while
minimized in a noisy channel. This result is of fundamental interest, but might
also have practical implications in extending the distance of secure quantum
key distribution.Comment: 9 pages, 5 figure
Intercept Probability Analysis of Cooperative Wireless Networks with Best Relay Selection in the Presence of Eavesdropping Attack
Due to the broadcast nature of wireless medium, wireless communication is
extremely vulnerable to eavesdropping attack. Physical-layer security is
emerging as a new paradigm to prevent the eavesdropper from interception by
exploiting the physical characteristics of wireless channels, which has
recently attracted a lot of research attentions. In this paper, we consider the
physical-layer security in cooperative wireless networks with multiple
decode-and-forward (DF) relays and investigate the best relay selection in the
presence of eavesdropping attack. For the comparison purpose, we also examine
the conventional direct transmission without relay and traditional max-min
relay selection. We derive closed-form intercept probability expressions of the
direct transmission, traditional max-min relay selection, and proposed best
relay selection schemes in Rayleigh fading channels. Numerical results show
that the proposed best relay selection scheme strictly outperforms the
traditional direct transmission and max-min relay selection schemes in terms of
intercept probability. In addition, as the number of relays increases, the
intercept probabilities of both traditional max-min relay selection and
proposed best relay selection schemes decrease significantly, showing the
advantage of exploiting multiple relays against eavesdropping attack.Comment: 5 pages. arXiv admin note: substantial text overlap with
arXiv:1305.081
Security of Continuous Variable Quantum Cryptography
We discuss a quantum key distribution scheme in which small phase and
amplitude modulations of CW light beams carry the key information. The presence
of EPR type correlations provides the quantum protection. We identify universal
constraints on the level of shared information between the intended receiver
(Bob) and any eavesdropper (Eve) and use this to make a general evaluation of
security. We identify teleportation as an optimum eavesdropping technique.Comment: 6 figure
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