Homepage
Crypto
Index
Enigma
Hagelin
Fialka
Siemens
Philips
Nema
Transvertex
Gretag
Tadiran
Racal
USA
Spy sets
Burst encoders
Intercept
Covert
Radio
PC
Kits
Shop
News
Events
Wanted
Contact
Links
Logo (click for homepage)
Enigma I
The Service Enigma

In 1926, the German Army - then called the Reichswehr - adopted the Enigma machine. In early 1927, the first machine with an single-ended Steckerbrett (plug board) was developed. Later that year, the final version was released, with an improved double-ended Steckerbrett. It was based on the chassis of the Enigma D and was given the internal designator Ch. 11a. The first batch of machines (approx. 600 units) were delivered on 10 December 1927. The Rechswehr (the predecessor of the Wehrmacht) called this machine the Enigma I. It would be the standard on which all further Enigma machines, used by the German Army, were based.
 
This version of the Glühlampenmaschine (lamp machine) has three moving code wheels, a fixed reflector (UKW) and a Steckerbrett (plug board). The Steckerbrett was used exclusively for the German Army.

It was supplied with 5 different coding wheels, numbered I to V. Each wheel had 26 positions and had numbers (01-26) on the circumfere. The wiring of each wheel is given below.

About 20,000 machines of this type were manufactured by various manufacturers, but only a hand full have survived.
  
Click to enlarge

The Enigma I was used by both the Wehrmacht (Army) and the Luftwaffe (Airforce). It was later adopted by the Kriegsmarine (German Navy) where it was commonly known as the M3 (preceeded by the M1 and the M2). The only obvious differency between the Army version and the Navy version is that the wheels of the latter have letters (A-Z) around their perimiters.

The machine is known by different names:
  • Wehrmacht Enigma
  • Heeres Enigma
  • Army Enigma
  • Service Enigma
  • Army/GAF Enigma
  • 3-wheel Enigma
  • 3-wheeler
but the official name for it is Enigma I (Roman number 1) or Ch.11a.
 
Enigma Enigma Front View Serial Warning Steckerbrett The

 
Extra wheels
The Enigma I was supplied with 5 coding wheels, but only 3 of them were in the machine at any time. Each day, the operator would place 3 wheels in the machine in a particular order, as instructed by the codebook.
 
The remaining two (unused) wheels were stored in a small wooden box. The image on the right shows an example of such a storage box with two wheels.

In the picture, wheels I and V are currently stored inside the box, whilst wheels II, III and IV are fitted in the machine.

Other types of boxes are known to exist, but this is the most common model.
  
Click to enlarge

 

 
Enigma Uhr
During WWII, the Germans made several attempts to make the Enigma more secure.

In July 1944, the German Luftwaffe came up with a smart device called Enigma Uhr, which was introduced without any prior warning whatsoever. It was attached to the side of an Enigma I and connected directly to the Steckerbrett.

 More information
  

 
Wiring
Below is the wiring for each wheel, the ETW and all three known UKWs. UKW-A was used before WWII [1]. UKW-B was the standard reflector during the war and UKW-C was only temporarily used during the war. The wiring of all 5 wheels is identical to the wiring of the first 5 wheels of the Enigma M3 (used by the Kriegsmarine) and the U-Boot Enigma M4.
 
Wheel ABCDEFGHIJKLMNOPQRSTUVWXYZ Notch Turnover #
ETW ABCDEFGHIJKLMNOPQRSTUVWXYZ      
I EKMFLGDQVZNTOWYHXUSPAIBRCJ Y Q 1
II AJDKSIRUXBLHWTMCQGZNPYFVOE M E 1
III BDFHJLCPRTXVZNYEIWGAKMUSQO D V 1
IV ESOVPZJAYQUIRHXLNFTGKDCMWB R J 1
V VZBRGITYUPSDNHLXAWMJQOFECK H Z 1
UKW-A1 EJMZALYXVBWFCRQUONTSPIKHGD      
UKW-B YRUHQSLDPXNGOKMIEBFZCWVJAT      
UKW-C FVPJIAOYEDRZXWGCTKUQSBNMHL      

 
References
  1. Philip Marks and Frode Weierud,
    Recovering the Wiring of Enigma's Umkehrwalze A

    Cryptologia, January 2000, Volume XXIV, Number 1, pp. 55-66.

Further information


Any links shown in red are currently unavailable.
© Copyright 2009-2010, Paul Reuvers & Marc Simons
If you like this website, why not make a donation?
Last changed: Thu,26 Aug 2010.18:38:00
Click for homepage