The current top political news of the day (Snowden leak) brings into sharp relief why encryption and the capabilities to break it receive so much attention.
It puts into context why a single algorithm (Shor’s) accounts for most of quantum computing’s notoriety and why quantum encryption receives so much funding.
All the more surprising then that Laszlo Kish’s work received comparatively little attention. After all, it poses a direct challenge to the field’s claim to offer the only communication channels where being tamper-proof is baked into the very protocol. Yet, with Charles Bennett et al. going for a knock-out, this decidedly changed. Now this exciting ‘match’ goes to the next round with the Kish et al. follow up paper, and it is quite the come-back. From the abstract:
Recently, Bennett and Riedel (BR) argued that thermodynamics is not essential in the Kirchhoff-law–Johnson-noise (KLJN) classical physical cryptographic exchange method in an effort to disprove the security of the KLJN scheme. They attempted to prove this by introducing a dissipation-free deterministic key exchange method with two batteries and two switches. In the present paper, we first show that BR’s scheme is unphysical and that some elements of its assumptions violate basic protocols of secure communication. Furthermore we crack the BR system with 100% success via passive attacks, in ten different ways, and demonstrate that the same cracking methods do not function for the KLJN scheme that employs Johnson noise to provide security underpinned by the Second Law of Thermodynamics. We also present a critical analysis of some other claims by BR; for example, we prove that their equations for describing zero security do not apply to the KLJN scheme. Finally we give mathematical security proofs for each of the attacks on the BR scheme and conclude that the information theoretic (unconditional) security of the KLJN method has not been successfully challenged.
The original post on this subject resulted in a high quality follow-up discussion on LinkedIn that I hope may get triggered again. After all, science is more fun as a spectator sport with well-informed running commentary.