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Current Injection Attack against the KLJN Secure Key Exchange

Chen Hsien-Pu, Mohammad Muneer, László B. Kish

Published Jun 1, 2016• 28 citations
Publisher

Abstract

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.

DOI
10.1515/mms-2016-0025

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Current Injection Attack against the KLJN Secure Key Exchange

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Abstract 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.

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We introduce the so far most efficient attack against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system. This attack utilizes the lack of exact thermal equilibrium in practical applications and is based on cable resistance losses and the fact that the Second Law of Thermodynamics cannot provide full security when such losses are present. The new attack does not challenge the unconditional security of the KLJN scheme, but it puts more stringent demands on the security/privacy enhancing protocol than for any earlier attack. In this paper we present a simple defense protocol to fully eliminate this new attack by increasing the noise-temperature at the side of the smaller resistance value over the noise-temperature at the side with the greater resistance. It is shown that this simple protocol totally removes Eve’s information not only for the new attack but also for the old Bergou-Scheuer-Yariv attack. The presently most efficient attacks against the KLJN scheme are thereby completely nullified.

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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
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.
Abstract 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.
The security of the Kirchhoff-law-Johnson-(like)-noise (KLJN) key exchange system is based on the fluctuation-dissipation theorem of classical statistical physics. Similarly to quantum key distribution, in practical situations, due to the non-idealities of the building elements, there is a small information leak, which can be mitigated by privacy amplification or other techniques so that unconditional (information-theoretic) security is preserved. In this paper, the industrial cable and circuit simulator LTSPICE is used to validate the information leak due to one of the non-idealities in KLJN, the parasitic (cable) capacitance. Simulation results show that privacy amplification and/or capacitor killer (capacitance compensation) arrangements can effectively eliminate the leak.
In this paper, the vulnerability of the Vadai, Mingesz and Gingl (VMG)- Kirchhoff-Law–Johnson-Noise (KLJN) Key Exchanger (Nature, Science Report 5 (2015) 13653) against two active attacks is demonstrated. The security vulnerability arises from the fact that the effective driving impedances are different between the HL and LH cases for the VMG-KLJN scheme; whereas for the ideal KLJN scheme, they are the same. Two defense schemes are shown against these attacks but each of them can protect against only one of the attack types; but not against the two attacks simultaneously. The theoretical results are confirmed by computer simulations.
We introduce the so far most efficient attack against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system. This attack utilizes the lack of exact thermal equilibrium in practical applications and is based on cable resistance losses and the fact that the Second Law of Thermodynamics cannot provide full security when such losses are present. The new attack does not challenge the unconditional security of the KLJN scheme, but it puts more stringent demands on the security/privacy enhancing protocol than for any earlier attack. In this paper we present a simple defense protocol to fully eliminate this new attack by increasing the noise-temperature at the side of the smaller resistance value over the noise-temperature at the side with the greater resistance. It is shown that this simple protocol totally removes Eve’s information not only for the new attack but also for the old Bergou-Scheuer-Yariv attack. The presently most efficient attacks against the KLJN scheme are thereby completely nullified.
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.