Re: Enigma Settings Sheets

I might be able to throw some light on the last few questions that Phil could not answer.

Frode Weierud

On 18 Feb 2012, at 14:34, Philip Marks wrote:

Here are some answers to Craig Heath's Enigma questions posted last week.

Phil Marks


-----Original Message-----
From: Bletchley Park discussion [mailto:BLETCHLEYPARK-0lvw86wZMd/[email protected]] On
Behalf Of Craig Heath
Sent: Friday, February 10, 2012 1:27 PM
To: BLETCHLEYPARK-0lvw86wZMd/[email protected]<mailto:BLETCHLEYPARK-0lvw86wZMd/[email protected]>
Subject: [BPARK] Enigma Settings Sheets


I have a couple of other random Enigma questions as well, so I may as well
ask while I'm here :-)
- What's the difference between an Enigma M2 and M3?


Here is an extract from some of my unpublished studies:
The naval Enigma machines were made in four different models, M 1 to M 4, with M 1 and M 2 also having the sub models, M 1a and M 2a. M 1 to M 3 where 3-wheel Enigma machines, while M 4 was the model number for the 4-wheel Enigma. It has been a wide held belief that M 3 and M 4 respectively referred to 3-wheel and 4-wheel naval Enigma machines, but the documents do not support this theory. The model designations M 1 to M 4 were simply model numbers where M 4 happened to be the designation for the 4-wheel naval Enigma. Curiously enough the in-house designation for the naval machines remained Ch. 11 g irrespective of which M-model was being produced; however the M 4 would sometimes be referred to as Ch. 11 g/4. Other names for the M 4 were Enigma M Form 4, Funkschlüssel Form M 4, or simply Funkschlüssel M 4. The different naval models that were first produced are shown in Table 1.
Production
Year

Total number
of machines

Serial numbers

Model

1934

401

M 501 – M 901

M 1

1935

60

M 902 – M 961

M 1a

1937

150

M 962 – M 1111

M 1a

1938

310

M 1112 – M 1421

M 2

1939

580

M 1422 – M 2001

M 2a, M 3

1940

800

M 2002 – M 2801

M 3

1941

1011

M 2802 – M 3812

M 4

Table 1. Production of Naval Enigma models from 1934 to 1941.

Further information on differences:
The number of machines made for the three main models of the 3-wheel Naval Enigma is shown to be M 1: 611 machines, M2: 770 machines, M3: 920 machines; a total of 2301 machines. Unfortunately we do not know much about the differences between these 3-wheel models, but there are some clues. In November 1978 there was an international meeting in Bonn – Bad Godesberg and Stuttgart with the theme Signal Intelligence and its Role in the Second World War.[1] A year later the proceedings from the conference was published in book form by the two organizers, Professor Dr. Jürgen Rohwer and Professor Dr. Eberhard Jäckel.[2] On page 129 in this book there are three photos from an early instruction manual for the Naval Enigma. One of these photos shows the machine together with the opened box for the extra wheels, Walzenkaste. On the inner, rear wall of the wheel box the plate with the serial number is fixed and it shows M 50_. This means the photos are of one of first nine machines, probably M 501, and therefore tells us that the photos are of a model M 1. The two other photos, which show the machine with open wheel cover, make it possible to identify a few characteristics of this model. First of all the wheel cover is equipped with two security locks instead of only one as on the M4. Secondly the machine does not seem to have a battery. In the place where the battery holder is normally situated there is instead a plate with a large power connector for connecting to an external power source. The machine is equipped with the usual green celluloid plate (Zellonplatte) that fits over the lamp field to reduce the eyestrain in weak light environments, but it is also equipped with a light screen (Lichtblende), which can be mounted behind the lamps field. This was intended to make it possible to use the machine in strong sunlight or under strong artificial lighting. On other Enigma versions it was usually the wooden box lid that served as a light screen because it was possible to lock it in a 45° half-open position.

________________________________

[1] Internationale Tagung in Bonn – Bad Godesberg und Stuttgart vom 15. – 18. November 1978: „Die Funkaufklärung und ihre Rolle im Zweiten Weltkrieg.“

[2] „Die Funkaufklärung und ihre Rolle im Zweiten Weltkrieg,“ ed. Jürgen Rohwer und Eberhard Jäckel, Motorbuch Verlag, Stuttgart, 1979.

-----------

There are probably other internal differences but they are probably minor, mechanical differences which does not in any way change the way the machine operates as a cipher machine.


- Deavours and Kruh 1985 (and hence Wikipedia) states that Enigma models
prior to I used a different rotor construction, where the turn-over notches
are fixed to the rotor core rather than to the settable ring.  Is this true?
(I haven't seen any other reference) and if so, which models?


D&K repeat this information in various articles.  I believe it to be true -
looking at Cryptologia 26:1, they seem to be saying it applied to the early
commercial models B, C, and D.  Can someone else on the list with more
knowledge than me pitch in here?


Enigma A and Enigma B were the large commercial printing Enigma machines and their rotors did not have notches for the wheel transport but used gear wheels. The first Enigma machines with notches were Enigma C and Enigma D. Enigma D was also called Enigma A 26 as the serial numbers were issued in the A-series and it was developed in 1926. The internal drawing reference was Ch. 8. Both Enigma C and D had the notches fixed to the wheel body and not on the alphabet ring. When the Reichwehr decided to buy Enigma machines in 1927 they also started discussion with the Enigma firm Chiffriermaschinen A-G (ChiMAG) to made modifications to the commercial D machine such as to make it more secure and better adapted to the Reichswehr use. The first modification was the addition of a Steckerbrett. These discussions started already in February 1928 and the details were ironed out in two meeting on 14 and 17 February 1928. On 1 March 1928 ChiMAG received an order to change the transport notches on two of the ordered Enigma machines, A 866 and A 867. Wheel I should have its notch on the alphabet or number ring at 25 (Y), wheel II at 13 (M) and wheel III at 04 (D). So the wheel notches of the three first Enigma wheels were  decided already in March 1928. ChiMAG replied on 6 March 1928 that they were ready to make this modification on all the other 400 machines that the Reichswehr had ordered and that for the time were stored with them for making the other modifications such as the addition of the Steckerbrett. The added cost would be 10.35 RM per machine.

Frode