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

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.

Resource Requirements and Speed versus Geometry of Unconditionally Secure Physical Key Exchanges

“…The Quantum Key Distribution (QKD) [5] and the Kirchhoff-Law-Johnson-Noise (KLJN) [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] secure key exchange are two examples of hardware-based secure key exchange concepts that are information theoretically secure [27]. Thus even with infinite computing resources the key will not be extracted by Eve, because the security offered by these schemes are based on fundamental laws of physics, to crack the key exchange would require Eve to break the underpinning laws of physics.…”

Random-Resistor-Random-Temperature Kirchhoff-Law-Johnson-Noise (RRRT-KLJN) Key Exchange

“…The Kirchhoff-law-Johnson-noise (KLJN) secure key distribution scheme [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] is a classical-statistical physical alternative to the quantum key distribution. Figure 1 depicts a binary version of the KLJN scheme and shows that, during a single-bit exchange, the communicating parties (Alice and Bob) connect their randomly chosen resistor (including its Johnson noise generator) to a wire channel.…”

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

“…The present paper concerns the classical statistical-physicsbased Kirchhoff-law-Johnson-noise (KLJN) key distribution system, delineated in Figure 1, which is no exception to the tradition of the research area, and the creation of the KLJN schemes [3,4] immediately triggered attacks [5][6][7]. The various attacks [5][6][7][8][9][10][11][12][13][14][15][16] have led to useful discussions [17][18][19][20][21][22][23], including corrections of flaws in the attacks [19][20][21][22][23] and developments of new defense protocols [5,10,11,13,24,25] as well as protocols that have increased immunity against attacks in general [24][25][26][27]. Furthermore, KLJN schemes that are totally immune to a certain attack have been presented [13,[28][29][30] as has a new system that is immune to all existing attacks [31].…”

“…Furthermore, KLJN schemes that are totally immune to a certain attack have been presented [13,[28][29][30] as has a new system that is immune to all existing attacks [31]. Responses to the attacks have included plain denials of their validity [18,[21][22][23], and in some cases experimental results that purportedly supported an attack have been found flawed [23]. The debates sometimes represent a standoff between opposing parties with different scientific backgrounds, which is a typical feature of science debates on breakthrough results in physics, as observed already by Max Planck [32].…”

“…A general comment is that GAA's paper is poorly documented and void of details regarding simulations: for example, what cable model or software was used, how were the noise generated, what simplifications were assumed, etc? All of these questions point at essential information needed for assessing the validity of, and and potential flaws in, GAA's simulations [14,[22][23][24].…”