Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1411.0818 · Fluctuation and Noise Letters

Analysis of an Attenuator Artifact in an Experimental Attack by Gunn–Allison–Abbott Against the Kirchhoff-Law–Johnson-Noise (KLJN) Secure Key Exchange System

Laszlo B. Kish, Zoltán Gingl, Robert Mingesz, Gergely Vadai, Janusz Smulko, Claes-Göran Granqvist

Published Dec 25, 2014• 38 citations
arXivHTMLPDF

Abstract

A recent paper by Gunn–Allison–Abbott (GAA) [L. J. Gunn et al., Scientific Reports 4 (2014) 6461] argued that the Kirchhoff-law–Johnson-noise (KLJN) secure key exchange system could experience a severe information leak. Here we refute their results and demonstrate that GAA's arguments ensue from a serious design flaw in their system. Specifically, an attenuator broke the single Kirchhoff-loop into two coupled loops, which is an incorrect operation since the single loop is essential for the security in the KLJN system, and hence GAA's asserted information leak is trivial. Another consequence is that a fully defended KLJN system would not be able to function due to its built-in current-comparison defense against active (invasive) attacks. In this paper we crack GAA's scheme via an elementary current-comparison attack which yields negligible error probability for Eve even without averaging over the correlation time of the noise.

DOI
10.1142/s021947751550011x

Related papers

ANALYSIS OF THE ATTENUATOR-ARTIFACT IN THE EXPERIMENTAL ATTACK OF GUNN-ALLISON-ABBOTT AGAINST THE KLJN SYSTEM

László B. Kish, Zoltán Gingl, Róbert Mingesz +3 more

After briefly summarizing our general theoretical arguments, we show that, the experienced strong information leak at the Gunn-Allison-Abbott attack [Scientific Reports 4 (2014) 6461] against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange scheme, resulted from a serious design flaw of the system. The attenuator broke the single Kirchhoff-loop into two coupled loops. This is an illegal operation because the single loop is essential for the security, thus the observed leak is obvious. We demonstrate this by cracking the system with an elementary current comparison attack yielding close to 1 success probability for Eve even without averaging within a sub-correlation-time measurement window. A fully defended KLJN system would not be able to function, at all, due to its built-in current-comparison defense against active (invasive) attacks.

•Jan 1, 2014•0 citations

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

László B. Kish, Claes G. Granqvist

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.

arXiv:1606.02697•Metrology and Measurement Systems•Jul 18, 2016•22 citations

ON THE "CRACKING" EXPERIMENTS IN GUNN, ALLISON, ABBOTT, "A DIRECTIONAL COUPLER ATTACK AGAINST THE KISH KEY DISTRIBUTION SYSTEM"

Hsien-Pu Chen, László B. Kish, Claes‐Göran Granqvist +1 more

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. In a former paper [http://vixra.org/pdf/1403.0964v4.pdf], we proved that CAA's wave-based attack is unphysical. Here we address their experimental results regarding this attack. Our analysis shows that GAA virtually claim that they can identify, in a few correlation times that, from two Gaussian distributions with zero mean, which one is wider when their relative width difference is <10 -4 . Normally, such decision would need millions of correlations times to observe. We identify the experimental artifact causing this situation: existing DC current and/or ground loop (yielding slow deterministic currents) in the system. It is important to note that, while the GAA's cracking scheme, the experiments and the analysis are invalid, there is an important benefit of their attempt: our analysis implies that, in practical KLJN systems, DC currents ground loops or any other mechanisms carrying a deterministic current/voltage component must be taken care of to avoid information leak about the key.

•Jan 1, 2014•0 citations

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

Hsien-Pu Chen, László B. Kish, Claes G. Granqvist +1 more

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.

arXiv:1405.2034•Metrology and Measurement Systems•Aug 20, 2014•39 citations

A Static-loop-current Attack Against the Kirchhoff-Law-Johnson-Noise (KLJN) Secure Key Exchange System

Mutaz Y. Melhem, László B. Kish

In this study, a new attack against the Kirchhoff-Law-Johnson-Noise (KLJN) key distribution system is explored. The attack is based on utilizing a parasitic voltage-source in the loop. Relevant situations often exist in the low-frequency limit in practical systems, especially when the communication is over a distance, or between different units within an instrument, due to a ground loop and/or electromagnetic interference (EMI). Our present study investigates the DC ground loop situation when no AC or EMI effects are present. Surprisingly, the usual current/voltage comparison-based defense method that exposes active attacks or parasitic features (such as wire resistance allowing information leaks) does not function here. The attack is successfully demonstrated and proposed defense methods against the attack are shown.

Applied Sciences•Feb 15, 2019•23 citations

Transient attacks against the Kirchhoff–Law–Johnson–Noise (KLJN) secure key exchanger

Shahriar Faysal Ferdous, László B. Kish

We demonstrate the security vulnerability of an ideal Kirchhoff–Law–Johnson–Noise key exchanger against transient attacks. Transients start when Alice and Bob connect a wire to their chosen resistor at the beginning of each clock cycle. A transient attack takes place during a short duration of time, before the transients reflected from the end of Alice and Bob mix together. The information leak arises from the fact that Eve (the eavesdropper) monitors the cable and analyzes the transients during this time period. We will demonstrate such a transient attack, and then, we introduce a defense protocol to protect against the attack. Computer simulations demonstrate that after applying the defense method the information leak becomes negligible.

Applied Physics Letters•Apr 3, 2023•9 citations
A recent paper by Gunn–Allison–Abbott (GAA) [L. J. Gunn et al., Scientific Reports 4 (2014) 6461] argued that the Kirchhoff-law–Johnson-noise (KLJN) secure key exchange system could experience a severe information leak. Here we refute their results and demonstrate that GAA's arguments ensue from a serious design flaw in their system. Specifically, an attenuator broke the single Kirchhoff-loop into two coupled loops, which is an incorrect operation since the single loop is essential for the security in the KLJN system, and hence GAA's asserted information leak is trivial. Another consequence is that a fully defended KLJN system would not be able to function due to its built-in current-comparison defense against active (invasive) attacks. In this paper we crack GAA's scheme via an elementary current-comparison attack which yields negligible error probability for Eve even without averaging over the correlation time of the noise.
After briefly summarizing our general theoretical arguments, we show that, the experienced strong information leak at the Gunn-Allison-Abbott attack [Scientific Reports 4 (2014) 6461] against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange scheme, resulted from a serious design flaw of the system. The attenuator broke the single Kirchhoff-loop into two coupled loops. This is an illegal operation because the single loop is essential for the security, thus the observed leak is obvious. We demonstrate this by cracking the system with an elementary current comparison attack yielding close to 1 success probability for Eve even without averaging within a sub-correlation-time measurement window. A fully defended KLJN system would not be able to function, at all, due to its built-in current-comparison defense against active (invasive) attacks.
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.
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. In a former paper [http://vixra.org/pdf/1403.0964v4.pdf], we proved that CAA's wave-based attack is unphysical. Here we address their experimental results regarding this attack. Our analysis shows that GAA virtually claim that they can identify, in a few correlation times that, from two Gaussian distributions with zero mean, which one is wider when their relative width difference is <10 -4 . Normally, such decision would need millions of correlations times to observe. We identify the experimental artifact causing this situation: existing DC current and/or ground loop (yielding slow deterministic currents) in the system. It is important to note that, while the GAA's cracking scheme, the experiments and the analysis are invalid, there is an important benefit of their attempt: our analysis implies that, in practical KLJN systems, DC currents ground loops or any other mechanisms carrying a deterministic current/voltage component must be taken care of to avoid information leak about the key.
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.
In this study, a new attack against the Kirchhoff-Law-Johnson-Noise (KLJN) key distribution system is explored. The attack is based on utilizing a parasitic voltage-source in the loop. Relevant situations often exist in the low-frequency limit in practical systems, especially when the communication is over a distance, or between different units within an instrument, due to a ground loop and/or electromagnetic interference (EMI). Our present study investigates the DC ground loop situation when no AC or EMI effects are present. Surprisingly, the usual current/voltage comparison-based defense method that exposes active attacks or parasitic features (such as wire resistance allowing information leaks) does not function here. The attack is successfully demonstrated and proposed defense methods against the attack are shown.
We demonstrate the security vulnerability of an ideal Kirchhoff–Law–Johnson–Noise key exchanger against transient attacks. Transients start when Alice and Bob connect a wire to their chosen resistor at the beginning of each clock cycle. A transient attack takes place during a short duration of time, before the transients reflected from the end of Alice and Bob mix together. The information leak arises from the fact that Eve (the eavesdropper) monitors the cable and analyzes the transients during this time period. We will demonstrate such a transient attack, and then, we introduce a defense protocol to protect against the attack. Computer simulations demonstrate that after applying the defense method the information leak becomes negligible.