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Discret
Manual wheel cipher system - wanted item

Discret (or Diskret) was a wheel-based manual cipher system, created in 1899 by Dr. Friedrich Rehmann in Karlsruhe (Germany). It was called Geheim- und Weltschreibmaschine (Secret and World Typewriter) and could be used both as a typewriter and as a simple cipher machine.

The device consists of two concentrical discs, each with the full alphabet in upper and lower case, numbers and punctuation marks. Typewriting was achieved by turning the handle (on the disc) to the desired letter and pressing the lever at the left all the way down. The letter would then be printed on a piece of paper that was laying flat at the bottom.

The cryptographic principle of Discret is alphabet substitution (Vigenère). The small knob is used to rotate the inner disc to a predetermined offset. The sender then informs the receiver of the chosen offset. The receiver then performs the reverse.
  
The Discret cipher machine

The image above shows a typical Discret machine that used to be part of the collection of Scryption in Tilburg (Netherlands), until the museum was dissolved in 2011. It now belongs to the University of Karlsruhe. During the exhibition SuperTU/esday in February 2010, we had a good chance to examine this machine further. Below are some detailed pictures we took at the event. Discret is completed by a wooden dust cover, which is missing from the one shown here.

The Discret cipher machine Close-up of the concentric discs Another view at the discs The mechanism behind the alphabet discs Driving gear Detail of the lock Close-up of the driving gear Discret, seen from the rear.
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The Discret cipher machine
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Close-up of the concentric discs
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Another view at the discs
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The mechanism behind the alphabet discs
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Driving gear
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Detail of the lock
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Close-up of the driving gear
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Discret, seen from the rear.

Known locations
The Discret is a highly-wanted collectors item, especially since not many of them have survived. They do, however, turn up at auctions every now and then and some are on public display in museums. Below are some suggestions if you want to see a real Discret.

Help wanted
At present, no further information about this machine is available. We would very much like to know more about it and about its history. If you know more about it, please contact us.

References
  1. The Virtual Typewriter Museum, Diskret
    Retrieved April 2012.
Further information
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Crypto Museum. Created: Monday 16 August 2010. Last changed: Friday, 04 August 2017 - 20:46 CET.
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