A Static-Loop-Current Attack against the KLJN Secure Key Exchange System

Melhem, Mutaz Y.; Kish, László B.

doi:10.20944/preprints201806.0157.v1

Cited by 5 publications

(21 citation statements)

References 22 publications

(63 reference statements)

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“…Several potential security vulnerabilities of the KLJN system have been addressed in previous research [4,42,[73][74][75][76][77][78][79][80][81][82][83][84][85][86]. However, in each case it was shown that these attacks do not compromise the unconditional security of the KLJN scheme because, similarly to quantum encryption, the information leak can be eliminated by defense hardware and privacy amplification.…”

Section: { } M a Bmentioning

confidence: 99%

“…However, if there is, that serves with potential information leak toward Eve. Papers [75,76] explored passive attack schemes that exploit the existence of parasitic DC sources, which is typical in digital circuitry through nonzero ground resistance (ground loop effects). In [75] the parasitic DC source is located at one end of the information channel while in [76] DC sources are located at both ends.…”

Section: Loop Current Attacksmentioning

confidence: 99%

“…It was shown that non-zero information leak exists which can be eliminated by various methods, such as filtering, compensation, increased temperature, privacy amplification, etc. [75,76].…”

Section: Loop Current Attacksmentioning

confidence: 99%

“…Eve can attack the secure bit exchange if she knows the time function U AAC (t) of the periodic source. The attack has the same basic steps as the DC attack procedure described in [75,76]:…”

Section: Attack In the Low-frequency Limitmentioning

confidence: 99%

“…where N i + is the number of samples that are above a threshold voltage U th,i which is fixed during the i-th bit exchange period. The new aspect of the low-frequency AC attacks compared to the DC attacks [75,76] is that here the threshold U th,i varies between bit exchange periods. The actual threshold U th,i is the time average of the periodic component over the i-th bit exchange period:…”

Section: Attack In the Low-frequency Limitmentioning

confidence: 99%

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Alternating (AC) Loop Current Attacks Against the KLJN Secure Key Exchange Scheme

et al. 2021

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Recently, several passive and active attack methods have been proposed against the Kirchhoff–Law–Johnson–Noise (KLJN) secure key exchange scheme by utilizing direct (DC) loop currents. The DC current attacks are relatively easy, but their practical importance is low. On the other hand, parasitic alternating (AC) currents are virtually omnipresent in wire-based systems. Such situations exist due to AC ground loops and electromagnetic interference (EMI). However, utilizing AC currents for attacks is a harder problem. Here, we introduce and demonstrate AC current attacks in various frequency ranges. The attacks exploit a parasitic/periodic AC voltage-source at either Alice’s or Bob’s end. In the low-frequency case, the procedure is the generalized form of the former DC ground-loop-based attack. In the high-frequency case, the power density spectrum of the wire voltage is utilized. The attack is demonstrated in both the low and the high-frequency situations. Defense protocols against the attack are also discussed.

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Section: { } M a Bmentioning

confidence: 99%

Section: Loop Current Attacksmentioning

confidence: 99%

“…It was shown that non-zero information leak exists which can be eliminated by various methods, such as filtering, compensation, increased temperature, privacy amplification, etc. [75,76].…”

Section: Loop Current Attacksmentioning

confidence: 99%

Section: Attack In the Low-frequency Limitmentioning

confidence: 99%

Section: Attack In the Low-frequency Limitmentioning

confidence: 99%

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Alternating (AC) Loop Current Attacks Against the KLJN Secure Key Exchange Scheme

et al. 2021

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Perspective—On the thermodynamics of perfect unconditional security

Chamon

Kish

2021

Applied Physics Letters

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A secure key distribution (exchange) scheme is unconditionally secure if it is unbreakable against arbitrary technological improvements of computing power and/or any development of new algorithms.There are only two families of experimentally realized and tested unconditionally secure key distribution technologies: Quantum Key Distribution (QKD), the base of quantum cryptography, which utilizes quantum physical photonic features; and the Kirchhoff-Law-Johnson-Noise (KLJN) system that is based on classical statistical physics (fluctuation-dissipation theorem). The focus topic of this paper is the thermodynamical situation of the KLJN system. In all the original works, the proposed KLJN schemes required thermal equilibrium between the devices of the communicating parties to achieve perfect security. However, Vadai, et al, in (Nature) Science Reports 5 ( 2015) 13653 shows a modified scheme, where there is a non-zero thermal noise energy flow between the parties, yet the system seems to resist all the known attack types. We introduce a new attack type against their system. The new attack utilizes coincidence events between the line current and voltages. We show that there is non-zero information leak toward the Eavesdropper, even under idealized conditions. As soon as the thermal equilibrium is restored, the system becomes perfectly secure again. In conclusion, perfect unconditional security requires thermal equilibrium.

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Man in the Middle and Current Injection Attacks Against the KLJN Key Exchanger Compromised by DC Sources

Melhem

Kish

2020

Fluct. Noise Lett.

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This study addresses a new question regarding the security of the Kirchhoff-Law-Johnson-Noise (KLJN) scheme compromised by DC sources at Alice and Bob: What is the impact of these parasitic sources on active attacks, such as the man-in-the-middle (MITM) attack, or the current injection attack if Alice and Bod did not eliminate these sources? The surprising answer is that the parasitic DC sources actually increase the security of the system because, in the case of the MITM attack, they make easier to uncover the eavesdropping than the ideal situation. In some of the cases, Eve can fix this deficiency but then the problem gets reduced to the original MITM attack to which the KLJN scheme is immune, it is already proven earlier.

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A Static-Loop-Current Attack against the KLJN Secure Key Exchange System

Cited by 5 publications

References 22 publications

Alternating (AC) Loop Current Attacks Against the KLJN Secure Key Exchange Scheme

Alternating (AC) Loop Current Attacks Against the KLJN Secure Key Exchange Scheme

Perspective—On the thermodynamics of perfect unconditional security

Man in the Middle and Current Injection Attacks Against the KLJN Key Exchanger Compromised by DC Sources

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