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Enigma KD
Commercial Enigma (K) with UKW-D - wanted item

The Enigma KD was a standard commercial Enigma K cipher machine, but had differently wired wheels and a rewirable reflector called UKW-D. Furthermore, the wheels each had nine turnover notches. It was used by the Militärisches Amt (Mil Amt) on the Berlin - Madrid - Lisbon link. It first appeared on 3 December 1944 and remained in use throughout the rest of the war. Mil Amt was a department of the German secret intelligence service and the successor to the Abwehr [1] .

The Enigma KD was supplied to Mil Amt with six different cipher wheels that each had nine turnover notches. Three of these wheels would be placed in the machine at any given time. The wiring of the Enigma KD used by Mil Amt is currently unknown (see wiring info below).

In 2009 an Enigma KD machine was discovered in the archives of the Swedish Intelligence Service FRA. It is currently not known whether this machine was used by the FRA or that it was confiscated after the war, but it appears to be identical to the Enigma KD used by Mil Amt.
Machine courtesy FRA Sweden [2]

The machine has three wheels, numbered I, II and III, each with nine turnover notches. The notches appear in the same position on all three wheels. The wiring of the wheels is given below. During the Enigma Reunion 2009 we were able to see the Enigma KD for the very first time, when it was brought to the event by FRA staff. The photographs presented on this page were made during that event. The FRA has also been helpful in recovering the wheel wiring.

The origin of the machine's name (KD) is unknown. It is suggested in [1] that it might be related to Kommando des Meldegebietes (KDM), which was the new name of the Abwehrstellen (Ast) after they were incorporated into the Reichssicherheitshauptamt (RSHA) on 1 June 1944. It is also possible that it was the merger of the machine's model (K) and the rewirable reflector (D).

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Wheel wiring
Below is the wiring if the first three wheels (I, II and III) of the Enigma KD that was found in the archives of the FRA [2]. This wiring might be identical to the first three wheels of the Enigma KD used by Mil Amt during WWII, but this is currently uncertain. The column marked 'Notch' shows the physical position of each notch on the circumference of the wheel, whilst the next column, marked 'Turnover', shows the letter that is visible through the window at the time of the turnover.

  1. Note that due to the nature of the (rewirable) UKW it does not have a fixed wiring. The table above shows the wiring of the UKW when the machine was (re)discovered at the FRA [2]. The actual wiring was probably changed frequently. Furthermore, the wiring as recorded by the FRA followed a different notation, starting with the contact at the top. For convenience, it has been converted to the official BP-notation. During WWII, Mil Amt changed the order of the wheels and the Ringstellung daily, whilst the Grundstellung (and probably also the wiring of UKW-D) was changed every three weeks [1].

  1. David Hamer, Geoff Sullivan and Frode Weierud
    Enigma Variations: An Extended Family of Machines

    Cryptologia, July 1998, Volume XXII, Number 3.

  2. Försvarets Radioanstalt (FRA), Sweden (National Defence Radio Establishment)
    Enigma KD from private collection of FRA.
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Crypto Museum. Created: Sunday 13 September 2009. Last changed: Tuesday, 15 September 2020 - 07:14 CET.
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