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1

Generalized DC loop current attack against the KLJN secure key exchange scheme

Melhem Mutaz Y., Kish Laszlo B.

Metrology and Measurement Systems

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2019

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Vol. 26, nr 4

607--616

EN

A new attack against the Kirchhoff-Law-Johnson-Noise (KLJN) secure key distribution system is studied with unknown parasitic DC-voltage sources at both Alice’s and Bob’s ends. This paper is the generalization of our earlier investigation with a single-end parasitic source. Under the assumption that Eve does not know the values of the parasitic sources, a new attack, utilizing the current generated by the parasitic dc-voltage sources, is introduced. The attack is mathematically analyzed and demonstrated by computer simulations. Simple defense methods against the attack are shown. The earlier defense method based solely on the comparison of current/voltage data at Alice’s and Bob’s terminals is useless here since the wire currents and voltages are equal at both ends. However, the more expensive version of the earlier defense method, which is based on in-situ system simulation and comparison with measurements, works efficiently.

2

Current Injection Attack against the KLJN Secure Key Exchange

Chen H.-P., Mohammad M., Kish L. B.

Metrology and Measurement Systems

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2016

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Vol. 23, nr 2

173--181

EN

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.

3

Unconditional security by the laws of classical physics

Mingesz R., Kish L. B., Gingl Z., Granqvist C.-G., Wen H., Peper F., Eubanks T., Schmera G.

Metrology and Measurement Systems

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2013

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Vol. 20, nr 1

3-16

EN

There is an ongoing debate about the fundamental security of existing quantum key exchange schemes. This debate indicates not only that there is a problem with security but also that the meanings of perfect, imperfect, conditional and unconditional (information theoretic) security in physically secure key exchange schemes are often misunderstood. It has been shown recently that the use of two pairs of resistors with enhanced Johnsonnoise and a Kirchhoff-loop - i.e., a Kirchhoff-Law-Johnson-Noise (KLJN) protocol . for secure key distribution leads to information theoretic security levels superior to those of today's quantum key distribution. This issue is becoming particularly timely because of the recent full cracks of practical quantum communicators, as shown in numerous peer-reviewed publications. The KLJN system is briefly surveyed here with discussions about the essential questions such as (i) perfect and imperfect security characteristics of the key distribution, and (ii) how these two types of securities can be unconditional (or information theoretical).

4

Data warehouses, mobile agents, and security

Stokłosa J.

Systems : journal of transdisciplinary systems science

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1999

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Vol. 4, No. 1-2

81-90

EN

A problem in the use of cryptographic mobile agents in the multilevel data warehouse environment is discussed. First, a systematic approach to cryptographic systems is presented. A cryptographic system is a collection of cryptographic primitives and protocols which help to ensure the confidentiality, integrity, and authenticity of data as well as secure key exchange for these primitives. Cryptography is a good tool for protecting sensitive data stored in data warehouses and transmitted through the corporate network. Mobile agents are intelligent programs that can migrate on a computer network. The authority of each agent can be established by way of cryptographic techniques.