Current and voltage based bit errors and their combined mitigation for the Kirchhoff-law-Johnson-noise secure key exchange

We classify and analyze bit errors in the current measurement mode of the Kirchhoff-law-Johnson-noise (KLJN) key distribution. The error probability decays exponentially with increasing bit exchange period and fixed bandwidth, which is similar to the error probability decay in the voltage measurement mode. We also analyze the combination of voltage and current modes for error removal. In this combination method, the error probability is still an exponential function that decays with the duration of the bit exchange period, but it has superior fidelity to the former schemes.Comment: 9 pages, accepted for publication in Journal of Computational Electronic

Noise properties in the ideal Kirchhoff-Law-Johnson-Noise secure communication system

In this paper we determine the noise properties needed for unconditional security for the ideal Kirchhoff-Law-Johnson-Noise (KLJN) secure key distribution system using simple statistical analysis. It has already been shown using physical laws that resistors and Johnson-like noise sources provide unconditional security. However real implementations use artificial noise generators, therefore it is a question if other kind of noise sources and resistor values could be used as well. We answer this question and in the same time we provide a theoretical basis to analyze real systems as well

Error Elimination in the KLJN Secure Key Exchange and Vehicular Applications

The Kirchhoff-law-Johnson-noise (KLJN) system is a classical physical secure key exchange scheme based on the Kirchhoff’s circuit loop law and the fluctuation-dissipation theorem of statistical physics. This dissertation contains two main studies related to this scheme: bit error analysis and removal, and applications in vehicular communication systems. The thesis starts with a presentation of some of the challenges faced by modern communications. It also includes a description of the working principle of the KLJN system and the motivation upon which this dissertation is built. Then, a study of the errors in this scheme is carried out. In the first part, the types of errors due to statistical inaccuracies in the voltage-based and current-based measurement modes are classified and analyzed. In both measurement modes and for all types of errors, at fixed bandwidth, the error probabilities decay exponentially versus the duration of the bit sharing period. In the second part, an error removal method is proposed to improve the fidelity of the system. This method is based on the combination of the voltage-based and current-based schemes and it drastically reduces the error probabilities. The second topic of study in the thesis explores a potential practical application for the KLJN key exchange scheme. First, we present a vehicular communication network architecture with unconditionally secure KLJN keys. Secondly, a new solution for secure KLJN key donation to vehicles is proposed and an upper limit for the lifetime of this key is given. A summary of the work is given in the last section and the main results of the research are discussed. These contributions include: closed-form expressions for the error probabilities in the KLJN system, error removal methods without the need of implementing any error correcting technique, and a new potential vehicular application for the KLJN scheme. Some of the future research initiatives related to these topics are discussed

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

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

Transient Attacks against the VMG-KLJN Secure Key Exchanger

The security vulnerability of the Vadai, Mingesz, and Gingl (VMG) Kirchhoff-Law-Johnson-Noise (KLJN) key exchanger, as presented in the publication "Nature, Science Report 5 (2015) 13653," has been exposed to transient attacks. Recently an effective defense protocol was introduced (Appl. Phys. Lett. 122 (2023) 143503) to counteract mean-square voltage-based (or mean-square current-based) transient attacks targeted at the ideal KLJN framework. In the present study, this same mitigation methodology has been employed to fortify the security of the VMG-KLJN key exchanger. It is worth noting that the protective measures need to be separately implemented for the HL and LH scenarios. This conceptual framework is corroborated through computer simulations, demonstrating that the application of this defensive technique substantially mitigates information leakage to a point of insignificance