Absolutely Secure Communications by Johnson-like Noise and Kirchhoff's Laws

TL;DR

This paper reviews the security of classical physical communication systems based on Johnson-like noise and Kirchhoff's laws, emphasizing their thermodynamic foundations and discussing recent developments and open questions.

Contribution

It provides a comprehensive survey of secure key exchange protocols grounded in thermodynamics and classical physics, highlighting their advantages and unresolved issues.

Findings

Classical physical systems can offer high security based on thermodynamic principles.

Recent developments explore systems where the Second Law's relevance is questioned.

Open questions remain about the security and practical application of these systems.

Abstract

We survey the most important results and some recent developments about the secure key exchange protocol where the security is based on the Second Law of Thermodynamics and the robustness of classical physical information. We conclude that a classical physical system offers a higher level of control and security during the communication. We also mention some recent attempts inspired by this communicator to create other systems where Alice and Bob do not form an organic single system and/or the Second Law is irrelevant. It seems philosophically that they cannot be unconditionally secure, however it is yet an open question how to crack them; how can they be best used for conditionally secure communications, and what are the practical implications.