50 research outputs found
Current Injection Attack against the KLJN Secure Key Exchange
The Kirchhoff-law-Johnson-noise (KLJN) scheme is a statistical/physical
secure key exchange system based on the laws of classical statistical physics
to provide unconditional security. We used the LTSPICE industrial cable and
circuit simulator to emulate one of the major active (invasive) attacks, the
current injection attack, against the ideal and a practical KLJN system,
respectively. We show that two security enhancement techniques, namely, the
instantaneous voltage/current comparison method, and a simple privacy
amplification scheme, independently and effectively eliminate the information
leak and successfully preserve the system's unconditional security
Analysis of an attenuator artifact in an experimental attack by Gunn-Allison-Abbott against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system
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.Comment: Accepted for publication in Fluctuation and Noise Letters, on
November 3, 201
On the "cracking" scheme in the paper "A directional coupler attack against the Kish key distribution system" by Gunn, Allison and Abbott
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 (2010) 2140-2142], 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 time-derivative
nature of GAA's scheme which tends to enhance all of these artifacts.Comment: This version is accepted for publication in Metrology and Measurement
System
Resource requirements and speed versus geometry of unconditionally secure physical key exchanges
The imperative need for unconditional secure key exchange is expounded by the
increasing connectivity of networks and by the increasing number and level of
sophistication of cyberattacks. Two concepts that are information theoretically
secure are quantum key distribution (QKD) and Kirchoff-law-Johnson-noise
(KLJN). However, these concepts require a dedicated connection between hosts in
peer-to-peer (P2P) networks which can be impractical and or cost prohibitive. A
practical and cost effective method is to have each host share their respective
cable(s) with other hosts such that two remote hosts can realize a secure key
exchange without the need of an additional cable or key exchanger. In this
article we analyze the cost complexities of cable, key exchangers, and time
required in the star network. We mentioned the reliability of the star network
and compare it with other network geometries. We also conceived a protocol and
equation for the number of secure bit exchange periods needed in a star
network. We then outline other network geometries and trade-off possibilities
that seem interesting to explore.Comment: 13 pages, 7 figures, MDPI Entrop