The Rehmann Diskret
The Rehmann Diskret is a typewriter equipped with an integrated encryption function. Developed around 1899 in Berlin and Karlsruhe, it predates the widespread adoption of cipher machines by approximately three decades. Its encryption mechanism is comparatively simple. Despite its historical significance very little is known about the machine’s history.
The Rehmann Diskret (shown here at the Charlotte Symposium 2026) is an index typewriter with an integrated encryption function.
Unlike a conventional typewriter with a full keyboard, an index typewriter uses only a single key (located on the left side of the machine). Before printing a character, the operator selects the desired letter using the character wheel. Pressing the key then prints the letter currently indicated on the wheel.
The encryption function of the Rehmann Diskret (shown here in the collection of the Technical Museum Vienna) is based on a simple substitution cipher. The machine contains a second character wheel integrated into the main character wheel. This inner wheel can be rotated relative to the outer wheel, creating an offset between the plaintext and ciphertext alphabets.
The inner wheel can be rotated relative to the outer wheel, creating an offset between the plaintext and ciphertext alphabets.
The encryption function of the Rehmann Diskret (shown here at the Typewriter Museum in Partschins) is not particularly secure.
The Rehmann Diskret (shown here at the Beck Typewriter Museum in Pfäffikon, Switzerland) was probably invented by Richard Beger, a manufacturer of glassware and metal products in Deuben, near Dresden. Very little is known about this person.
As can be seen from this advertising poster, the Rehmann Diskret was sold for 75 Marks. Adjusted for inflation, this would correspond to more than €2,000 today. The machine was therefore a very expensive product.
The Rehmann Diskret (shown here at the Technical Museum in Vienna) was also sold by the company Giernat & Schröter under the name “Discret.” Unfortunately, nothing is known about this company either.
At the Technical Museum Vienna, a Rehmann Diskret is displayed alongside numerous typewriters without encryption capabilities. As a result, visitors with an interest in cryptography can easily overlook this remarkable machine.
Unfortunately, very little is known about the Rehmann Diskret overall. This specimen was displayed at a collectors’ gathering in Essen in 2014.
The Rehmann Diskret (shown here at the Heinz Nixdorf MuseumsForum in Paderborn) cannot have been particularly successful. So far, I am aware of only eight examples, which are housed in various museums or belong to private collectors. There are probably more, but it certainly wasn’t produced in large quantities.
Literature
Back to Crypto Galleries