In the trail of an Enigma message |
![]() |
Introduction | ![]() |
![]() | |
The whole process of of encoding and decoding message is rather complex
and can be very time consuming. Nevertheless, many Enigmae were used in
the field and in U-boats. Setting up an Enigma and operating it, wasn't
easy either. But the most difficult task that had to be carried out
every day, was probably the breaking of the daily keys at Bletchley Park.
This pages describes the path of a message, from the German Enigma operator
in the field, to the Intelligence officers in the UK and elsewhere.
|
Sending a message | ![]() |
![]() | |
Interception by the Y-Stations | ![]() |
![]() | |
In order to copy with the large number of messages sent by the Germans each day, a big intercept organisation had to be exploited. This organisation would be called the Y Service. Hundreds of man and woman would write down long sequences of seemingly unrelated letters each day. |
| |||
The Teleprinter Room | ![]() |
![]() | |
The Y Stations were scattered all over the UK, but were mainly located at
the coast line, in order to avoid radio interference. Some German
signals were so weak that the intercepts from several stations had to
be combined in order to get a complete message.
In the early days, messages were brought to Bletchley Park by courier, but later on in the war, teleprinters were used to send the messages via secure telephone lines. This photograph shows an example of a teleprinter room (not at BP). |
| |||
Breaking the Code | ![]() |
![]() | |
Most of the messages were sent to Bletchley Park via teleprinter.
Here is an example of a typical message at it was received by the
BP cryptanalists.
The codebreakers used coloured pencils to put their own markings
on the paper sheet, as can be seen here. The letters MAFPKR
were probably the initial settings for that day.
Other markings show Red, to indicate the origin of the message (e.g. Luftwaffe) and 'Key 31/10' which tells us that the message was encrypted with the key for 31 October 1944. The message was received at Bletchley Park on 1 November 1944 as we can see in the preample of the message. |
| |||
The bombes | ![]() |
![]() | |
Breaking the Enigma messages wasn't an easy job at all.
Once the cryptanalists had a sufficiently large crib to
work on they would use it to program the Bombe, which
was some kind of mechanical computer.
A crib is a part of the plaintext, that is likely to occur at the start of the message, 'to the chief in command'. The longer the crib, the easier it would be to break the key. The bombe shown here was used to break 3-wheel Enigma traffic. The machines used to break the 4-wheel Enigma messages, was even more complicated and had several extensions. |
| |||
Interpreting the message | ![]() |
![]() | |
Once the key was broken, a modified British Type-X machine
(the British variant of the Enigma) was used to decode the
message. The Type-X machine would print it on long strokes
of paper, which were glued to the back of the message.
The message then went on to another part of Bletchley Park, were someone, capable of interpreting German, would clean up the message. Word breaks were added and typos were corrected. Once complete, the message was sent to the Intelligence department, who would use the contents of the message for strategic purposes. |
| |||
A real example of a message | ![]() |
![]() | |
Below is an example of a real message as it was sent on 21 September 1938.
The message was sent in three parts and is reproduced here with kind
permission from Frode Weierud, Enigma Researcher.
|
+ HRKM 13617 1807 - |
Once it was decoded, it would look like this:
|
AUF BEFEHL DES OBERSTEN BEFEHLSHABERS SIND IM |
As the Enigma only contains the letters A-Z, a space and
full-stop are missing. Furthermore, any special German
characters, such as the ü (u-umlaut), had to be spelled
in an alternative manner (e.g. 'ue'). Numbers were also
missing on the Enigma keyboard and had to be spelled.
In plain German, the message looks like this:
|
Auf Befehl des Obersten Befehlshabers sind im Falle, |
Translated into plain English, the message looks like this:
|
The Commander-in-Chief orders as follows: |
© Copyright Paul Reuvers. Last changed: Wed,15 Oct 2003.17:28:04 | ||
![]() |