High Quality Content by WIKIPEDIA articles! The Kish cypher is a technique purported to maintain secure communications utilizing classical statistical physics due to Laszlo B. Kish. The Kish cypher is a physical secure layer (hardware-based technique) where the security is provided by the laws of physics (the second law of thermodynamics and Kirchhoff`s laws) and it should not be confused with a software-based approach called the Kish–Sethuraman (KS) cypher.