Second-law-attack, and eliminating all cable resistance attacks in the Johnson noise based secure scheme
László B. Kish, Claes Goran Granqvist · arXiv (Cornell University) · 2014
We introduce the so far most efficient attack against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchanger. The attack utilizes the lack of exact thermal equilibrium at practical applications due to the cable resistance loss. Thus the Second Law of Thermodynamics cannot provide full security. While the new attack does not challenge the unconditional security of the KLJN scheme, due to its more favorable properties for Eve, it requires higher requirements for the security/privacy enhancing protocol than any earlier versions. We create a simple defense protocol to fully eliminate this attack by increasing the noise-temperature at the side of the lower resistance value. We show that, this simple defense protocol totally eliminates Eve's information not only in this but also in the old (Bergou)-Scheuer-Yariv attack. Thus the so far most efficient attack methods become useless against the KLJN scheme.