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On page 14 of the WCS, table 11 lists the code letters belonging to the air temperature T.

The weather short key (abbreviation: WKS ) was a code book that was used by the submarines of the German Navy during the Second World War to encrypt the weather reports they sent via radio (“weather short signal”).

history

The key machine Enigma was primarily used to keep the radio communications between the commander of the submarines (BdU) and the German submarines, which were sunk by Allied ships and convoys in the Atlantic and Mediterranean, secret .

Since the danger of the discovery and localization of the submarines by Allied radio direction finding (“ Huff-Duff ”) was seen when they sent longer radio messages, and also for reasons of data compression , in order to increase the security of the encryption, it was only sought to send short sayings as possible. The weather short key was used for this purpose, in which, as is customary with code books, a number of weather reports often required in routine radio communication were compared with corresponding secret letter combinations. The table  (picture) shows the coding of the air temperature as an example. 

A +28 °C   +3 °C
B +27 °C   +2 °C
C +26 °C   +1 °C
D +25 °C    0 °C
E +24 °C   -1 °C
F +23 °C   -2 °C
G +22 °C   -3 °C
H +21 °C   -4 °C
I +20 °C   -5 °C
J +19 °C   -6 °C
K +18 °C   -7 °C
L +17 °C   -8 °C
M +16 °C   -9 °C
N +15 °C  -10 °C
O +14 °C  -11 °C
P +13 °C  -12 °C
Q +12 °C  -13 °C
R +11 °C  -14 °C
S +10 °C  -15 °C
T  +9 °C  -16 °C
U  +8 °C  -17 °C
V  +7 °C  -18 °C
W  +6 °C  -19 °C
Y  +5 °C  -20 °C
Z  +4 °C  -21 °C

Instead of a detailed message such as the air temperature is plus ten degrees , only the letter "S" was encrypted with the Enigma and then together with other encrypted information such as water temperature, air pressure, wind direction, wind strength, visibility conditions, cloud cover, position and sender, which were also sent before the Encryption encoded with similar tables of the weather short key were sent over the air. Due to the approximate knowledge of the position of the submarine, the recipient (BdU) was able to translate the letter "S", which according to the table above could mean 10 ° C or -15 ° C, back into the correct temperature.

Similarly, the direction and type of swell was also coded with just one letter: 

--------------------------------------------------------------------------
Richtung, aus der     |                  Art der Dünung
die Dünung kommt      |  niedrig   | mittelhoch |    hoch    |
--------------------------------------------------------------------------
 N                    |     a      |     i      |     q      |
 NO                   |     b      |     j      |     r      |
 O                    |     c      |     k      |     s      |
 SO                   |     d      |     l      |     t      |
 S                    |     e      |     m      |     u      |
 SW                   |     f      |     n      |     v      |
 W                    |     g      |     o      |     w      |
 NW                   |     h      |     p      |     x      |
 Keine Dünung         |            |            |            |     y
 Durcheinanderlaufend |            |            |            |     z

In the course of time, different editions of the weather short key were used. The first edition had the code name "Weimar". It was replaced on January 20, 1942 by the edition "Eisenach". On March 10, 1943, the third edition of the weather code came into force, which was codenamed "Naumburg".

It was fatal for the Germans that by hijacking the U 110 submarine on May 9, 1941 , the British were not only able to capture an intact Enigma-M3 key machine , but also all of their secret documents, including the weather code "Weimar" as well as the short signal booklet fell into the hands and this was not noticed by the German leadership. The code breakers in Bletchley Park, England , succeeded in breaking the encryption on the M3 and deciphering the German submarine radio messages.

There was an interruption in the ability to decipher (“black-out”) when the M3 was replaced by the Enigma-M4 on February 1, 1942 . In contrast to the M3, this has not only three, but four rollers that are used for encryption. The black-out could only be overcome after the British destroyer HMS Petard succeeded on October 30, 1942 in seizing the German submarine U 559 in the Mediterranean and stealing the weather short key edition "Eisenach" and the current version of the short signal booklet.

In autumn 1944, in the final phase of the Second World War, the courier method was tested as a technical innovation as a new method for transmitting short weather signals on some submarines. However, it has probably only been used on a single boat in the front line.

Cinematic reception

A weather code can be seen in the British feature film Enigma - The Secret , which is based on the novel Enigma and thematizes the deciphering work of the British code breakers from Bletchley Park. This is an authentic German book that was captured by a German submarine during World War II. The various radio messages have also been realistically generated and encrypted for the film according to the original rules and procedures.

Known copies

Only a few surviving copies of the weather short key are known, one in the Federal Archives-Military Archives in Freiburg im Breisgau and one in the National Cryptologic Museum in the United States . A copy of the third edition of the WKS “Naumburg” was sold by the Bonhams auction house in May 2018 for US $ 225,000 (approx. € 194,000).

literature

  • Arthur O. Bauer: Radio direction finding as an Allied weapon against German submarines 1939-1945 . Self-published, Diemen Netherlands 1997. ISBN 3-00-002142-6
  • Friedrich L. Bauer : Deciphered Secrets. Methods and maxims of cryptology. 3rd, revised and expanded edition. Springer, Berlin a. a. 2000, ISBN 3-540-67931-6 .
  • Paul N. Pfeiffer: Breaking the German Weather Ciphers in the Mediterranean Detachment G, 849th Signal Intelligence Service . In: Cryptologia . tape XXII , no. 4 , October 1998, p. 354-369 , doi : 10.1080 / 0161-119891886975 (English).
  • Heinz Ulbricht: The Enigma cipher machine - deceptive security . A contribution to the history of the intelligence services. Dissertation Braunschweig 2005. PDF; 4.7 MB

Web links

Individual evidence

  1. ↑ Friedrich L. Bauer: Deciphered secrets. Methods and maxims of cryptology. 3rd, revised and expanded edition. Springer, Berlin a. a. 2000, p. 75.
  2. ↑ Robert Harris: Enigma . Novel. Weltbild, Augsburg 2005. ISBN 3-89897-119-8
  3. ^ Tony Sale: Making the Enigma ciphers for the film "Enigma" . Retrieved March 26, 2008.
  4. ↑ PDF; 7 MB p. 722, accessed on March 1, 2018.
  5. ↑ Bonhams-Auktionhaus Lot 269 Fine books and manuscripts Jun 12, 2018, 1:00 PM EDT.