What kind of noise guarantees security for the Kirchhoff-Loop-Johnson-Noise key exchange?
This work addresses a specific security issue in physical-layer key exchange systems, providing a theoretical foundation but is incremental as it builds on prior assumptions and does not cover all attack types.
The paper tackles the problem of determining which noise properties guarantee security for the Kirchhoff-Loop-Johnson-Noise (KLJN) key exchange system, proving mathematically that only a normal distribution with specific scaling ensures security and showing through simulations that improper noise selection leads to insecurity.
This article is a supplement to our recent one about the analysis of the noise properties in the Kirchhoff-Law-Johnson-Noise (KLJN) secure key exchange system [Gingl and Mingesz, PLOS ONE 9 (2014) e96109, doi:10.1371/journal.pone.0096109]. Here we use purely mathematical statistical derivations to prove that only normal distribution with special scaling can guarantee security. Our results are in agreement with earlier physical assumptions [Kish, Phys. Lett. A 352 (2006) 178-182, doi: 10.1016/j.physleta.2005.11.062]. Furthermore, we have carried out numerical simulations to show that the communication is clearly unsecure for improper selection of the noise properties. Protection against attacks using time and correlation analysis is not considered in this paper.