Conference article

The Zschweigert Cryptograph is one of the many cipher machine designs developed in the years following the First World War (1914-1918). It was invented by textile engineer Rudolf Zschweigert, who had designed programmable stitching machines before and apparently transfered his computing expertise to cryptology. Unlike the Enigma and as good as all other crypto devices of the time, the Zschweigert Cryptograph implements a transposition cipher, not a substitution cipher. To the author’s knowledge, it was the first encryption machine that worked with keys provided on punched cards. The goal of this paper is to introduce the Zschweigert Cryptograph and its history, to provide a mathematical specification of its encryption algorithm, and to explore how it can be cryptanalyzed. It will be shown that the Zschweigert Cryptograph, which was probably never used in practice, was insecure even by the standards of the 1920s and not convenient enough to compete with other encryption machines of the time.

Zschweigert Cryptograph; Rudolf Zschweigert; encryption machine; transposition cipher