Security and performance analysis of the Kirchhoff-Law-Johnson-Noise secure key exchange protocol

The Kirchhoff-Law-Johnson-(like)-Noise (KLJN) key exchange system is a promising low-cost alternative to the quantum key distribution and is based solely on the laws of classical physics. Although several papers have been published in the field, there is still an ongoing debate about the security of the method. In our paper we will give an overview the most important findings about the security of the KLJN system and show the effects of the non-idealities of the system on the information leak. We will also analyze different methods of proposed cracking the KLJN protocol, including the latest directional coupler attack.