Secure communications using the KLJN scheme

Hadi Zayyani, Felipe A. P. de Figueiredo, Mohammad Salman +1 more

In this paper, a Resistor Hopping (RH) scheme with the addition of biases is proposed for secure Kirchhoff Law Johnson-Noise (KLJN) communication. The RH approach enables us to increase the bit rate of secure communication between Alice and Bob, while also ensuring that the inherent unconditional security of KLJN is satisfied. The biases are added to the proposed scheme to better distinguish between Gaussian distributed noises in terms of their means, rather than just using variances. Throughout the paper, we strive to minimize biases to achieve a power-efficient scheme. For the detection part of the proposed algorithm, a Maximum-Likelihood (ML) detector is derived. The separability condition of Gaussian distributions is investigated, along with the provision of a threshold-based detector that offers both simple and optimal thresholds in terms of minimizing the error probability. Some analysis of the proposed RH-KLJN communication scheme is provided, including Physical Layer Security (PLS) equations. Simulation results demonstrate the advantages of the proposed scheme over the classical KLJN scheme, offering a higher data rate and lower bit error probability at the expense of increased complexity.

Nkm Nieke Aerts

Christiana Chamon

The Kirchhoff-Law-Johnson-Noise (KLJN) secure key exchange scheme leverages statistical physics to enable secure communication with zero average power flow in a wired channel. While the original KLJN scheme requires significant power for operation, a recent wireless modification, TherMod, proposed by Basar claims a “low power” implementation. This paper critically examines this claim. We explain that the additional components inherent in the wireless adaptation substantially increase power consumption, rendering the “low power” assertion inappropriate. Furthermore, we clarify that the security claims of the original KLJN scheme do not directly translate to this wireless adaptation, implying significant security breach. Finally, the scheme looks identical to one of the stealth communicators from 2005, which was shown not to be secure.

Kyatsandra G. Nagananda

Andor Tönköly, Robert Mingesz

The Kirchhoff-Law–Johnson-Noise (KLJN) key exchange protocol offers a classical, physics-based alternative to quantum key distribution for achieving informationtheoretic security. It offers a classical and cost-effective solution to secure communications. In this paper we present a simulation framework that models the entire KLJN loop, enabling detailed exploration of the scheme, and propose workflows to generate KLJN key-exchange probability density functions, and to validate their accuracy against analytically calculated ones. We also use our simulation to empirically verify that voltage and current standard deviations of a KLJN scheme follow chi-distributions, a result that crucially impacts threshold optimization and bit-classification algorithms. We also introduce correction techniques that reconstruct the original statistical behavior after signal-processing operations such as windowing and low-pass filtering, which are essential for reducing transients between bit transfers and enhancing security. This work integrates statistical signal analysis, and simulation-driven validation to strengthen the theoretical and practical foundations of KLJN-based secure communication.