The encryption codes of German spies in World War 2 are still little researched. Today I will introduce an interesting spy telegram that was sent from Buenos Aires to Hamburg in 1940.

Intelligence work plays an important role in every war. In World War 2, the Germans operated their secret service “Abwehr” in order to gather information of military relevance about their enemies.


German spy codes

The Abwehr tried hard to deploy a worldwide network of spies, but they were never as successful as other secret services, like the CIA, the Mossad or the KGB. As the war went on, Abwehr director Wilhelm Canaris together with some of his closest colleagues became important opponents of Hitler. Canaris was arrested and murdered in a Nazi concentration camp in April 1945.

One of the Abwehr’s strategies was to send secret agents to enemy countries and to other places of interest. These agents were camouflaged as businessmen, travellers, journalists or somehow else. Some of the information they were looking for was easily available by observing harbours or simply reading  newspapers. In addition, Abwehr agents tried to hire local people with access to less obvious information. While this did work in many cases, the Abwehr was not especially successful in recruiting high-ranked persons in the military or the government.

One major challenge for the Abwehr was to communicate with their foreign agents. Some messages were sent by radio or telegram, others by mail. Both steganography and cryptography played an important role. The USA, Great Britain and some other countries established censorship agencies with thousands of employees in order to search for spy messages in the mail and in telegrams.

So far, the encryption and steganography techniques used by the Abwehr are little researched. There must have been many different methods in use. Of course, ciphers used by spies had to be simple, cheap and unobtrusive. Encryption machines like the Enigma could not be used.  Usually, the only tools available for enciphering and deciphering were paper and pencil.


A spy message from Argentina

The following telegram (today kept by the British National Archives) was sent by a German named Ottomar Müller from Buenos Aires, Argentina, to a company named NLT Technico in Hamburg, Germany:


Here’s the English translation of it:


The telegram has the appearance of a commercial note. It contains several code numbers, which was quite common for a business telegram of the time. The meanings of code numbers were listed in codebooks. The main purpose of using code numbers was to make telegrams shorter (and therefore cheaper), while privacy only played a minor role.

The telegram above was forwarded to British crypto experts, who recognised that it was a spy message. The two code numbers containing a slash were derived from a German-English dictionary (e.g., 264/6 means page 264, word number 6).


With the dictionary the crypto experts found out that 264/6 stands for “pier” and 112/3 for “December”. With this information, the telegram can be partially encrypted:


The British codebreakers could not find out what the numbers 244, 1345 and 4992 mean. They might stand for persons, places or time/date information. My guess is that the secret message only consists of the five code numbers, while the rest is meaningless. If I’m right, the message reads “Pier 244 1345 December 4992” – whatever this means.

Has anybody ever heard of a company named NLT Technico? What do the numbers 244, 1345 and 4992 mean? And who is “NAN”? If you have an idea, please tell me.

Further reading: Who can make sense of a child murderer’s encrypted notes?

Kommentare (9)

  1. #1 Thomas
    20. Oktober 2016

    According to McGaha, The Politics of Espionage (p. 185), Ottomar Müller in 1940 was solicitated by the Hamburg-based firm Schmitt and Company which operated as a front for the Abwehrstelle Hamburg. I suppose “NLT Technico” was a codename of this firm.
    Müller’s task was to provide reports on British ships entering and leaving Buenos Aires. Maybe the undecoded numbers refer to such ships.

  2. #2 Bernhard Gruber
    21. Oktober 2016

    “as other secret services, like the CIA, the Mossad or the KGB”: Yes, as these organisations did not exist at this time: Founded 1947/1949/1954.

  3. #3 Klaus Schmeh
    21. Oktober 2016

    I know, but it’s still possible to compare the Abwehr with CIA, Mossad and KGB.

  4. #4 Max Baertl
    21. Oktober 2016

    Möglicherweise ist das erste N in “Nan” nur ein Tippfehler und es heißt richtig “Man”

  5. #5 Thomas
    21. Oktober 2016

    Meine Theorie zu “Nan”:
    Im Dezember 1939 war das deutsche Schiff “Admiral Graf Spee” vor Montevideo auf Befehl des Kapitäns versenkt worden. Die Besatzung wurde nach Argentinien gebracht und interniert. Die Abwehr bemühte sich darum, Besatzungsmitglieder nach Deutschland zurückzubringen, wofür japanische Schiffe herangezogen wurden. Meine Vermutung ist, dass Müller als in Buenos Aires eingesetzter Agent der Abwehr mit der japanischen Reederei Nanyo Kaiun über einen Transport von Besatzungspersonal nach Deutschland verhandelt hatte. Im Telegramm teilte er der unter dem Decknamen “NLT Technico” für die Abwehrstelle Hamburg tätigen Firma mit, dass die mit “Nan” bezeichnete japanische Reederei ihr Angebot aufrechterhielt.

  6. #6 Thomas
    21. Oktober 2016

    Einige Tage nach dem Telegramm wurden aus Argentinien geflohene Besatzungsmitglieder der “Graf Spee” auf einem japanischen Schiff festgenommen,

  7. #7 Thomas
    21. Oktober 2016

    Das Bundesarchiv hat Unterlagen zu “Fragen der Rückholung von Teilen der Besatzung des Panzerschiffes “Admiral Graf Spee”, leider nicht online als Digitalisat, Möglicherweise ließe sich dort mehr erfahren.

  8. #8 Thomas
    22. Oktober 2016

    If you are interested in cryptography and its broad variety used by the Abwehr in South America during WW II: .
    The dictionary code is mentioned on page 67. In Chile it was based on the Langenscheidt´s Spanish-German Pocket dictionary.

  9. #9 Thomas
    23. Oktober 2016

    Ergänzend zu #5:
    Eine “NLT Technico” ist im Hamburger Adressverzeichnis für 1940 nicht zu finden, was aber auch nicht verwunderlich ist: Dabei handelte es sich um das “Drahtwort” des Unternehmens. Da sich die Telegrammgebühren nach der Länge des übermittelten Textes (einschließlich der Angabe des Empfängers) richtete, hatten Unternehmen ein sogenanntes Drahtwort. Dieses wurde u.a. – wie heute die E-Mail-Adresse – auf Briefbögen unter den Kontaktdaten angegeben und musste dem eigentlichen Firmennamen nicht einmal besonders ähnlich sein. Da die elektronische Übermittlung schon beim Empfängerpostamt endete, musste dieses in einem Verzeichnis o.ä. nachsehen, welche Firma in seinem Bezirk hinter dem Drahtwort auf einem empfangenen Telegramm steckte. Um “NLT Technico” einer bestimmten Firma zuordnen zu können, müsste man deshalb entweder das damalige Verzeichnis des zuständigen Empfängerpostamts in Hamburg oder Geschäftsunterlagen des Unternehmens haben.