Mutaz Y. Melhem

Mutaz Melhem, Laszlo Kish

This study addresses a new question regarding the security of the Kirchhoff-Law-Johnson-Noise (KLJN) scheme compromised by DC sources at Alice and Bob: What is the impact of these parasitic sources on active attacks, such as the man-in-the-middle (MITM) attack, or the current injection attack? The surprising answer is that the parasitic DC sources actually increase the security of the system because, in the case of the MITM attack, they make easier to uncover the eavesdropping. In some of the cases Eve can fix this deficiency but then the problem gets reduced to the original MITM attack to which the KLJN scheme is immune, it is already as proven earlier

Mutaz Y. Melhem, Laszlo B. Kish

A new attack against the Kirchhoff Law Johnson Noise (KLJN) secure key distribution system is studied with unknown parasitic DC voltage sources at both Alices and Bobs ends. This paper is the generalization of our earlier investigation with a single end parasitic source. Under the assumption that Eve does not know the values of the parasitic sources, a new attack, utilizing the current generated by the parasitic dc voltage sources, is introduced. The attack is mathematically analyzed and demonstrated by computer simulations. Simple defense methods against the attack are shown. The earlier defense method based solely on the comparison of current/voltage data at Alice's and Bob's terminals is useless here since the wire currents and voltages are equal at both ends. However, the more expensive version of the earlier defense method, which is based on in situ system simulation and comparison with measurements, works efficiently.

Mutaz Y. Melhem, Laszlo B. Kish

A new attack against the Kirchhoff-Law-Johnson-Noise (KLJN) key distribution system is explored. The attack is based on utilizing a parasitic dc-voltage-source in the loop. Relevant situations often exist in the low-frequency limit in practical systems, especially when the communication is over a distance, due to a ground loop and/or electromagnetic interference (EMI). Surprisingly, the usual current/voltage comparison based defense method that exposes active attacks or parasitic features (such as wire resistance allowing information leak) does not function here. The attack is successfully demonstrated. Proposed defense methods against it are shown.