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

作者：Kish Laszlo B^*; Gingl Zoltan; Mingesz Robert; Vadai Gergely; Smulko Janusz; Granqvist Claes Goran

来源：Fluctuation and Noise Letters, 2015, 14(1): 1550011.

DOI：10.1142/S021947751550011X

• KLJN secure key exchange system
• directional coupler
• unconditional security
• experimental artifacts

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 builtin 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.

• 出版日期2015-3