The Kryha cipher machine

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Introduction

The Kryha machine is one of the very first cipher machines available to both businesses and government agencies (diplomatic and military). It dates back to the 1920s.

The most expert cryptologists quickly realized its weaknesses. However, the length of its key (several hundred letters) and the use of disordered alphabets may have fooled amateurs.

Even though sales weren't spectacular, Kryha machines are not very rare. They frequently appear in auction catalogs or even directly on online marketplaces like eBay. Unfortunately, sales at the time of its production never allowed its creator (Von Kryha) to make a fortune. On the contrary, he went bankrupt several times.

History

The Kryha machine was created by Alexander Von Kryha, born in 1891. Of Russian origin, he immigrated to Germany after the communist takeover.

In 1924, he created his first machine, which he called the "Kryha Standard." It was a mechanical machine that, from the outset, offered very little security.

The biggest deal was the sale of the Kryha license for the US to A.M. Evalenko in 1932 for $100,000. Evalenko tried to sell the Kryha to the American army but without success. The challenge he proposed to Army, was broken by Frideman and his team in 2 hours and 41 minutes (link).

Towards the end of the 1930s, he improved his machine, but it remained far inferior to competing machines (notably the Hagelin and Enigma machines). Towards the end of the war, his company ceased operations. In the 1950s, he tried again to sell the machines, but his company went bankrupt and he committed suicide in 1955.

Different models

Kryha offered three versions of his machine:

  • A purely mechanical version (the "standard" form) the size of a shoebox. Encrypted (or plaintext) letters were read on a dial.
  • A printing version, called the Elektric model, composed of two typewriters, which served as input/output units, and a partially electrical and partially mechanical casing that performed the encryption.
  • A tiny mechanical version, called Liliput, the size of a pocket watch.
Undoubtedly, its low security and the fact that it could not print (in its standard version) explain its poor sales.

References

Books & Articles

  • Schmeh, K. 2010. "Alexander von Kryha and his Encryption Machines." Cryptologia 34(4): 291-300. Note:
  • Marks, P. 2011. Operational Use and Cryptanalysis of the Kryha Cipher Machine. Cryptologia 35(2): 114-155.
  • Fuensanta, J. R. S. 2004. "Mechanical Cipher Systems in the Spanish Civil War", Cryptologia, 28:3. Note: The Kryha machine was one of the machines used by the Spanish forces.