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← U-534 messages
← Enigma M4
← Enigma
  
Enigma M4 message
Message from Dönitz - 1 May 1945

The following message was sent by Grand Admiral Dönitz on 1 May 1945 at 06:55, announcing his appointment as Hitler's successor. Hitler was already dead at this point. He committed suicide a day earlier, on 30 April at about 15:30. Dönitz was officially informed about this by Reichsleiter Bormann on 30 April at 18:35. Please note that this message was sent before Hitler's death was officially announced on 1 May 1945 at 22:30. Broken again by Michael Hörenberg (see below).

The image on the right show the message form as it was found aboard the sunken U-boat U534. Although this sheet has been at the bottom of the sea for more than 40 years, most of it is still readable. Nevertheless, decoding each individual Enigma operator's handwriting can be a real challenge by itself, as you can see here.

Below are the settings of the Enigma machine, followed by the ciphertext and the plaintext. Note that the first two groups of the ciphertext are the message indicator. They should be ignored as they are not part of the text.
  

One special feature of this message can be spotted immediately. The settings below reveal that reflector C was used in combination with Zusatzwalze (Greek wheel) Beta rather than Gamma. Although Enigma messages were commonly written down in groups of 5 letters, the Navy used 4-letter groups. They were written down on special message forms (Schlüsselzettel/Funkspruch).

Although the message forms were rather large, there often wasn't enough room for the entire text, which is why the Enigma operators used every free spot on the form for a 4-letter group, even columns that were intended for something else. With the current message, the last two 4-letter groups are at the top of the bottom left column under the heading 'Abgegeben An'. This is a repeat of the message indicator that is also in the first two 4-letter groups of the message.

Reading a German plaintext message after it has been decoded is not easy. There are no spaces and some infrequently used letters are used as punctuation marks. Furthermore, many abbreviations and military expressions are used. Please note that the text contains errors which can be the result of typing errors, writing error and errors in sending and receiving morse code. Dan Girard has written a great article about reconstructing the message below [4].


Enigma settings
  • Enigma: M4
  • Umkehrwalze (reflector): C
  • Zusatzwalze (Greek wheel): Beta
  • Walzenlage (wheel order): 568
  • Ringstellung (ring setting): EPEL
  • Grundstellung (start position): NAEM
  • Steckern (plugs): AE BF CM DQ HU JN LX PR SZ VW
  • Message key: ??? (see below)
Message key
The first two 4-letter groups of the message are the message indicator. To ensure good reception, the message indicator is repeated at the end of the message. These message indicators are not part of the actual message and should therefore be omitted from the ciphertext below. The message indicator is:
   
   DUHF TETO
   
Through a complex process of lookup tables [2], this produces the Verfahrenkenngruppe:
   
   QEOB
   
Entering QEOB at the basic setting (Grundstellung) NEAM, reveals the message key:
   
   CDSZ
   
The Enigma wheels are now set to CDSZ in order to decode the rest of the message.

Ciphertext
   DUHF TETO LANO TCTO UARB BFPM HPHG CZXT DYGA HGUF XGEW KBLK GJWL QXXT
   GPJJ AVTO CKZF SLPP QIHZ FXOE BWII EKFZ LCLO AQJU LJOY HSSM BBGW HZAN
   VOII PYRB RTDJ QDJJ OQKC XWDN BBTY VXLY TAPG VEAT XSON PNYN QFUD BBHH
   VWEP YEYD OHNL XKZD NWRH DUWU JUMW WVII WZXI VIUQ DRHY MNCY EFUA PNHO
   TKHK GDNP SAKN UAGH JZSM JBMH VTRE QEDG XHLZ WIFU SKDQ VELN MIMI THBH
   DBWV HDFY HJOQ IHOR TDJD BWXE MEAY XGYQ XOHF DMYU XXNO JAZR SGHP LWML
   RECW WUTL RTTV LBHY OORG LGOW UXNX HMHY FAAC QEKT HSJW DUHF TETO

Plaintext
   KRKRALLEXXFOLGENDESISTSOFORTBEKANNTZUGEBENXXICHHABEFOLGELNBEBEFEHLERH
   ALTENXXJANSTERLEDESBISHERIGXNREICHSMARSCHALLSJGOERINGJSETZTDERFUEHRER
   SIEYHVRRGRZSSADMIRALYALSSEINENNACHFOLGEREINXSCHRIFTLSCHEVOLLMACHTUNTE
   RWEGSXABSOFORTSOLLENSIESAEMTLICHEMASSNAHMENVERFUEGENYDIESICHAUSDERGEG
   ENWAERTIGENLAGEERGEBENXGEZXREICHSLEITEIKKTULPEKKJBORMANNJXXOBXDXMMMDU
   RNHFKSTXKOMXADMXUUUBOOIEXKP

Formatted
   KRKR ALLE XX
   FOLGENDES IST SOFORT BEKANNTZUGEBEN XX
   ICH HABE FOLGELNBE BEFEHL ERHALTEN XX
   J ANSTERLE DES BISHERIGXN REICHSMARSCHALLS J GOERING J SETZT DER
   FUEHRER SIE Y HVRR GRZSSADMIRAL Y
   ALS SEINEN NACHFOLGER EIN X SCHRIFTLSCHE VOLLMACHT UNTERWEGS X
   ABSOFORT SOLLEN SIE SAEMTLICHE MASSNAHMEN VERFUEGEN Y DIE SICH
   AUS DER GEGENWAERTIGEN LAGE ERGEBEN X
   GEZ X REICHSLEITEI KK TULPE KK J BORMANN J
   OB.D.MMM DURNH FKST.KOM.ADM.UUU BOOIE.KP

In normal German
   KRIEGSNOTMELDUNG [An] Alle:
   
   Folgendes ist sofort bekanntzugeben:
   Ich habe folgende Befehl erhalten:
   'Anstelle des bisherigen Reichsmarschalls 'Göring' setzt der Führer
   Sie, Herr Großadmiral, als seinen Nachfolger ein.
   Schriftlische Vollmacht unterwegs.
   Ab sofort sollen Sie sämtliche Maßnahmen verfügen,
   die sich aus die gegenwärtigen Lage ergeben.
   Gez. Reichsleiter (Tulpe) 'Bormann'
   
   [Von] Oberbefehlshaber der Marine,
   durch Funkstelle der Kommandierender Admiral der Unterseeboote.

Translated to English
   WAR EMERGENCY MESSAGE [To] All:
   
   The following is to be announced immediately:
   I have received the following order: 'In place of former
   Reichsmarschall 'Göring', the Führer has appointed you,
   Herr Grossadmiral, as his successor.
   Written authorization [is] on the way.
   Effective immediately, you are to order all measures
   that are required by the present situation.
   Signed, Reichsleiter (Tulpe) 'Bormann':
   
   [From] Commander-in-Chief of the Navy,
   [sent] by way of the Radio Station
   of the Commanding Admiral of Submarines



U-534
The message shown here was recovered from the German submarine U-534 that was sunk on 5 May 1945. In 1993 the ship was recovered and some Enigma messages were found intact. In 2012, Michael Hörenberg set out to break the recovered messages by means of distributed computing power, using a modified software Turing Bombe and ciphertext-only attacks.

The image on the right shows part of the original message sheet as it was recovered from the U-534. It was broken by Michael Hörenberg on 20 October 2012. You may download the original message sheets1 by using these links:

 Original message
 Alternative copy

The first one is a message on an original sheet (Schlüsselzettel), whilst the second one is a copy that was written at the back of another form. It was probably taken at a later time or date.
  

Reconstructing the ciphertext of the message above was not an easy task. Both copies of the ciphertext contain a series of mistakes that were probably caused by bad reception of the morse code, e.g. where an 'L' (•–••) was mistaken for an 'R' (•–•). Furthermore, the exact sequence of the 4-letter groups on the original form (Schlüsselzettel) was not entirely clear, whilst on the second copy one 4-letter group was missing completely. Dan Girard has written a great article in which he describes the difficulties he encountered when reconstructing the Dönitz Message [4].

 More about the U-534

  1. Enigma M4 messages reproduced here by kind permission from Michael Hörenberg [1].


References
  1. Michael Hörenberg, Message P-1030681
    1 May 1945. Broken 20 October 2012.

  2. Michael Hörenberg, The Kenngruppen System
    How to use the Kenngruppenbuch (K.Buch) and Doublebuchstabentauschtafel
    or: How did the Germans got the message key? July 2012.

  3. Dirk Rijmenants, Enigma Message Procedures
    Retrieved October 2012.

  4. Dan Girard, Degarbling the Dönitz Message
    24 October 2012.
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Crypto Museum. Created: Sunday 03 May 2015. Last changed: Saturday, 30 September 2017 - 10:26 CET.
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