scholarly journals On the “Cracking” Scheme in the Paper “A Directional Coupler Attack Against the Kish Key Distribution System” by Gunn, Allison and Abbott

2014 ◽  
Vol 21 (3) ◽  
pp. 389-400 ◽  
Author(s):  
Hsien-Pu Chen ◽  
Laszlo B. Kish ◽  
Claes G. Granqvist ◽  
Claes G. Granqvist
Keyword(s):  
Distribution System ◽  
Electromagnetic Waves ◽  
Directional Coupler ◽  
Key Distribution ◽  
Mean Square ◽  
Johnson Noise ◽  
Dc Offset ◽  
Relative Variance ◽  
Harmonic Components ◽  
Non Gaussian

Abstract Recently, Gunn, Allison and Abbott (GAA) [http://arxiv.org/pdf/1402.2709v2.pdf] proposed a new scheme to utilize electromagnetic waves for eavesdropping on the Kirchhoff-law-Johnson-noise (KLJN) secure key distribution. We proved in a former paper [Fluct. Noise Lett. 13 (2014) 1450016] that GAA’s mathematical model is unphysical. Here we analyze GAA’s cracking scheme and show that, in the case of a loss-free cable, it provides less eavesdropping information than in the earlier (Bergou)-Scheuer-Yariv mean-square-based attack [Kish LB, Scheuer J, Phys. Lett. A 374:2140-2142 (2010)], while it offers no information in the case of a lossy cable. We also investigate GAA’s claim to be experimentally capable of distinguishing—using statistics over a few correlation times only—the distributions of two Gaussian noises with a relative variance difference of less than 10-8. Normally such distinctions would require hundreds of millions of correlations times to be observable. We identify several potential experimental artifacts as results of poor KLJN design, which can lead to GAA’s assertions: deterministic currents due to spurious harmonic components caused by ground loops, DC offset, aliasing, non-Gaussian features including non-linearities and other non-idealities in generators, and the timederivative nature of GAA’s scheme which tends to enhance all of these artifacts.

Performance analysis of the “intelligent” Kirchhoff-Law-Johnson-Noise secure key exchange

2014 ◽  
Vol 33 ◽  
pp. 1460368
Author(s):  
Janusz Smulko
Keyword(s):  
Performance Analysis ◽  
Distribution System ◽  
Key Distribution ◽  
Key Exchange ◽  
Johnson Noise ◽  
Statistical Tools ◽  
Information Theoretic ◽  
The Wire ◽  
Averaging Time

The Kirchhoff-Law-Johnson-Noise (KLJN) secure key distribution system provides a way of exchanging information theoretic secure keys by measuring the random voltage and current through the wire connecting two different resistors at Alice's and Bob's ends. Recently new advanced protocols for the KLJN method have been proposed with enhanced performance. In this paper we analyze the KLJN system and compare with “intelligent” KLJN (iKLJN) scheme. This task requires the determination of the applied resistors and the identification of the various superpositions of known and unknown noise components. Some statistical tools to determine how the duration of the bit exchange window (averaging time) influences the performance of secure bit exchange will be explored.

scholarly journals Experimental Implementation of Non-Gaussian Attacks on a Continuous-Variable Quantum-Key-Distribution System

2007 ◽  
Vol 98 (3) ◽  
Author(s):  
Jérôme Lodewyck ◽  
Thierry Debuisschert ◽  
Raúl García-Patrón ◽  
Rosa Tualle-Brouri ◽  
Nicolas J. Cerf ◽  
...  
Keyword(s):  
Distribution System ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Experimental Implementation ◽  
Non Gaussian

scholarly journals Comments on “A New Transient Attack on the Kish Key Distribution System”

2016 ◽  
Vol 23 (3) ◽  
pp. 321-331 ◽  
Author(s):  
Laszlo B. Kish ◽  
Claes G. Granqvist
Keyword(s):  
Distribution System ◽  
Key Distribution ◽  
Key Exchange ◽  
Security Measures ◽  
Johnson Noise ◽  
Exchange System ◽  
Classical Physics ◽  
The One

Abstract A recent IEEE Access Paper by Gunn, Allison and Abbott (GAA) proposed a new transient attack against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system. The attack is valid, but it is easy to build a defense for the KLJN system. Here we note that GAA’s paper contains several invalid statements regarding security measures and the continuity of functions in classical physics. These deficiencies are clarified in our present paper, wherein we also emphasize that a new version of the KLJN system is immune against all existing attacks, including the one by GAA.

Performance Analysis of the "Intelligent" Kirchhoff-Law–Johnson-Noise Secure Key Exchange

2014 ◽  
Vol 13 (03) ◽  
pp. 1450024 ◽  
Author(s):  
Janusz Smulko
Keyword(s):  
Performance Analysis ◽  
Distribution System ◽  
Key Distribution ◽  
Key Exchange ◽  
Johnson Noise ◽  
Statistical Tools ◽  
The Wire ◽  
Averaging Time

The Kirchhoff-law–Johnson-noise (KLJN) secure key distribution system provides a way of exchanging theoretically secure keys by measuring random voltage and current through the wire connecting two different resistors at Alice's and Bob's ends. Recently new advanced protocols for the KLJN method have been proposed with enhanced performance. In this paper, we analyze the KLJN system and compare with the "intelligent" KLJN (iKLJN) scheme. That task requires determination of the applied resistors and identification of various superpositions of known and unknown noise components. Some statistical tools will be explored to determine how the duration of the bit exchange window (averaging time) influences the performance of the secure bit exchange.

scholarly journals Bit errors in the Kirchhoff-Law–Johnson-Noise secure key exchange

2014 ◽  
Vol 33 ◽  
pp. 1460367 ◽  
Author(s):  
Yessica Saez ◽  
Laszlo B. Kish ◽  
Robert Mingesz ◽  
Zoltan Gingl ◽  
Claes G. Granqvist
Keyword(s):  
Distribution System ◽  
Error Probability ◽  
Key Distribution ◽  
Key Exchange ◽  
Mitigation Strategy ◽  
Current Measurement ◽  
Combination Method ◽  
Exponential Dependence ◽  
Johnson Noise ◽  
Error Mitigation

We classify and analyze bit errors in the voltage and current measurement modes of the Kirchhoff-law–Johnson-noise (KLJN) secure key distribution system. In both measurement modes, the error probability decays exponentially with increasing duration of the bit sharing period (BSP) at fixed bandwidth. We also present an error mitigation strategy based on the combination of voltage-based and current-based schemes. The combination method has superior fidelity, with drastically reduced error probability compared to the former schemes, and it also shows an exponential dependence on the duration of the BSP.

Experimental study of the Kirchhoff-Law-Johnson-Noise secure key exchange

2014 ◽  
Vol 33 ◽  
pp. 1460365 ◽  
Author(s):  
Robert Mingesz
Keyword(s):  
Experimental Study ◽  
Distribution System ◽  
Communication Protocol ◽  
Experimental Tests ◽  
Key Distribution ◽  
Key Exchange ◽  
Theoretical Studies ◽  
Johnson Noise ◽  
Classical Physics ◽  
Dedicated Hardware

The Kirchhoff-Law-Johnson-Noise (KLJN) secure key distribution system provides a way of exchanging secure keys by using classical physics (electricity and thermodynamics). Several theoretical studies have addressed the performance and applicability of the communication protocol, and they have indicated that it is protected against all known types of attacks. However, until now, there have been very few real physical implementations and experimental tests of the protocol. With our work, we continue filling this gap. Details of implementing a KLJN based system are presented using a dedicated hardware and an off-the-shelf solution as well. Furthermore, the results of experimental tests and analysis of the performance will be presented.

scholarly journals Reconstruction of Diffusion Coefficients and Power Exponents from Single Lagrangian Trajectories

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 111
Author(s):  
Leonid M. Ivanov ◽  
Collins A. Collins ◽  
Tetyana Margolina
Keyword(s):  
Black Sea ◽  
Diffusion Coefficients ◽  
Current System ◽  
Mean Square Displacement ◽  
California Current ◽  
The Black Sea ◽  
Mean Square ◽  
California Current System ◽  
The Mean ◽  
Non Gaussian

Using discrete wavelets, a novel technique is developed to estimate turbulent diffusion coefficients and power exponents from single Lagrangian particle trajectories. The technique differs from the classical approach (Davis (1991)’s technique) because averaging over a statistical ensemble of the mean square displacement (<X2>) is replaced by averaging along a single Lagrangian trajectory X(t) = {X(t), Y(t)}. Metzler et al. (2014) have demonstrated that for an ergodic (for example, normal diffusion) flow, the mean square displacement is <X2> = limT→∞τX2(T,s), where τX2 (T, s) = 1/(T − s) ∫0T−s(X(t+Δt) − X(t))2 dt, T and s are observational and lag times but for weak non-ergodic (such as super-diffusion and sub-diffusion) flows <X2> = limT→∞≪τX2(T,s)≫, where ≪…≫ is some additional averaging. Numerical calculations for surface drifters in the Black Sea and isobaric RAFOS floats deployed at mid depths in the California Current system demonstrated that the reconstructed diffusion coefficients were smaller than those calculated by Davis (1991)’s technique. This difference is caused by the choice of the Lagrangian mean. The technique proposed here is applied to the analysis of Lagrangian motions in the Black Sea (horizontal diffusion coefficients varied from 105 to 106 cm2/s) and for the sub-diffusion of two RAFOS floats in the California Current system where power exponents varied from 0.65 to 0.72. RAFOS float motions were found to be strongly non-ergodic and non-Gaussian.

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