Operational Use and Cryptanalysis of the Kryha Cipher Machine

Abstract

The Kryha machine was introduced in 1924 and continued to be marketed into the 1950s. The cryptologic literature surveyed for this article includes descriptions of various models of the machine and methods of attacking it, but relatively little has been written about its operational use. This article reviews both published and archival material, and provides some examples of actual use and cryptanalysis from the period immediately before and during the Second World War.

Diplomatic Ciphers Used by Slovak Attaché During the WW2

“…From cryptological point of view, the cipher is a polyalphabetic substitution with individual alphabets rotated by the amount given by clocking se-quence of the machine. Such a system was known to be broken even before WW2 (Marks, 2011).…”