Five years ago an encrypted carrier pigeon message from World War II hit the news. So far, nobody has been able to decipher it.

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In August 2012, David Martin from Surrey, UK, made an interesting find. In the chimney of his house he discovered the skeleton of a carrier pigeon along with a message still wrapped to its leg. As it turned out, the message was encrypted:


The message is not dated. However, the pigeon wore a ring indicating that it was born in 1940. According to historians, the message was probably sent from France to England on D-Day (June 6th, 1944) by a Sergeant W. Stott. It seems possible that the pigeon was heading for Bletchley Park, where the British operated their crypto and codebreaking institution. Bletchley Park lies about 130 kilometers to the north of the finding place.


The pigeon cryptogram

The use of carrier pigeons was quite common in World War II. The British air force trained about 250,000 birds, forming the National Pigeon Service. Typically, the pigeons were dropped into Nazi occupied Europe using parachutes. Agents picked them up and provided them to the British military for sending messages back home.

As good as nothing is known about the ciphers the British used for encrypting their carrier pigeon traffic. The message found in Surrey is the only encrypted carrier pigeon message from WW2 I have ever heard of. It is therefore pretty hard to say what kind of encryption was used.  Crypto history experts at Bletchley Park (which is now a museum) and the British secret service GCHQ tried to decipher it, but to no avail.

Meanwhile many others have tried to break the pigeon encryption. At least two persons claimed to have solved the mystery, but none of these solutions has been accepted by crypto experts.

The carrier pigeon cryptogram is covered in a German blog post I wrote in 2013.


Hard to break

Here’s a transcription of the pigeon message:


The message contains 27 groups of five letters each. The group AOAKN appears twice – at the start and at the end. It might therefore be a call sign or something similar.

Here are a few hypotheses that have been discussed:

  • The message might have been encrypted with a manual cipher. To my regret, there seems to be no systematic overview on British manual ciphersused in WW2. A bigram substitution seems to be an interesting candidate.
  • A Slidex (a British WW2 lowtec encryption device) might have been used. However, this hypothesis was rejected by Nick Pelling.


  • The message might have been encrypted with the British encryption machine Typex (the Typex ressembles the German Enigma but is more advanced):


  • The message might have been encrypted with a codebook. If so, the only way to solve the message is finding the codebook that was used (the one shown below is certainly not the correct one). Even worse, in addition to the codebook, a second encryption step might have been applied – a quite common procedure.


The carrier pigeon cryptogram received a lot of media coverage. There’s no doubt that many skilled people tried to break it. We can therefore assume that the carrier pigeon cryptogram is extremely hard to decipher. Maybe one of my readers will be successful anyway.

Further reading: The Top 50 unsolved encrypted messages: 27. Ferdinand III’s encrypted letters

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Kommentare (6)

  1. #1 Thomas
    17. September 2017

    @ Klaus

    The link above leads to your article concerning emperor Ferdinand’s letter.

    Bigram substitution? Can a bigram substitution yield a ciphertext consisting of an odd number of letters?

    Slidex? The ciphertext contains all 26 letters. According to Wiki’s references – and the photo above – Slidex only used 17 letters from A to Q (vertically). Was there another version which made use of the whole alphabet?

  2. #2 Thorsten
    18. September 2017

    Regarding the claim of Didac Sánchez on solving the cipher I revisited the website of the 4yeo-Software Sánchez was developing. I still tells you, the software will be released in late 2016. More interestingly he ended the contest and published the solution, an excerpt of a Spanish book. I wonder, if anyone analysed the challenge cipher comparing cipher- and plain-text. I could not find anything on the first google search.

  3. #3 Thomas
    18. September 2017

    Probably the pidgeon cryptogram is based on a letter one-time pad (LOP) invented by Leo Marks, the chief cryptographer of Special Operations Executive (SOE) during WW2. He devised cryptographic systems for, among others, Free French (https://books.google.fr/books?id=I4zP8hSxIFIC&printsec=frontcover).
    The encrypting procedure is covered here : http://chris-intel-corner.blogspot.fr/2013/10/soe-cryptosystems-german-view.html (see images of sheets 4 – 6). Hence the first and the last group should be an encrypted indicator of the LOP table, wheras the second group contains the agent’s number encrypted with a special procedure. According to Marks, millions of LOP tables were produced.

  4. #4 Thomas
    18. September 2017

    Did he publish also the encryption procedure? If not, it should be impossible to check whether his alleged solution (an excerpt of a Spanish book in a message sent from France to England – what for?) is correct.

  5. #5 Thorsten
    18. September 2017

    Did he publish also the encryption procedure?

    No, he did not. I did not expect so anyhow. After all he wanted to sell this software that seems to depend on keeping the encryption procedure secretly. (I know, this is ridicilous.)

    an excerpt of a Spanish book in a message sent from France to England – what for?

    Sorry for being imprecise. The excerpt was used for the challenge created by himself to proof the encryption method is “undecipherable”. He did not provide any solution for the original WW2 message so far, although he claimed he deciphered it in 2015.

  6. #6 Thomas
    18. September 2017

    This blog archive provides many documents from the National Archives about the use of pigeons in WW2, f.e. in connection with D-Day: