Computational and probabilistic methods in cryptanalysis: the Kryha machine

Extract

In the early part of this century, a mechanical ‘ciphering machine’ was invented and marketed by a Berlin engineer, Alexander von Kryha. The Kryha machine performed a polyalphabetic substitution on text controlled by one of 1050 possible keys. In this lecture we describe the general principles of cryptanalysis and its interplay with probability theory and show how the Kryha machine may be cryptanalyzed.