Data Structures and Algorithms


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

Authors: Hsien-Pu Chen, Laszlo B. Kish, Claes-Göran Granqvist, Gabor Schmera

Recently, Gunn, Allison and Abbott (GAA) [] 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 [] that GAA’s mathematical model is unphysical. Here we analyze GAA’s cracking scheme and show that in the cable loss free case it serves less eavesdropping information than the old mean-square based attack, while in the loss-dominated case it offers no information. We also investigate GAA's experimental claim to be capable of distinguishing, with a poor statistics over a few correlation times, 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 experimental artifacts due to poor design that can lead to GAA’s assertions; deterministic currents due to spurious harmonic components ground loop, DC offset; aliasing; non-Gaussian features including non-linearities and other non-idealities in the generators; and the time-derivative nature of their scheme enhancing all these aspects.

Comments: 11 Pages. missing/incorrect abstract fixed; extended (second) version

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Submission history

[v1] 2014-04-10 23:52:54
[v2] 2014-04-11 08:37:35
[v3] 2014-05-15 06:52:11
[v4] 2014-05-15 23:12:47

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