On Friday the Heinz Nixdorf Museum will broadcast a number of radio messages encrypted with an Enigma. Codebreaking experts in Bletchley Park will try to decipher these cryptograms with WW2 technology. Enigma experts will try the same with computer support.

Breaking Enigma messages has a long history. Already in the 1930s, Polish mathematicians Marian Rejewski, Henryk Zygalski and Jerzy Różycki deciphered German Enigma ciphertexts.


Based on the Polish expertise, British codebreakers later developed a codebreaking machine, the Bombe (also known as Turing-Welshman Bombe), which enabled them to read hundreds of thousands of German Enigma messages during World War II.


In order to support their British colleagues, US codebreakers built a number of Bombes, too. Their task was to break the four-rotor Naval Enigma, which was especially hard to decipher.

After the end of WW2 the Enigma was hardly used any more. Breaking Enigma messages became obsolete. Most copies of the Bombe were disassembled. For decades the work on methods for deciphering the Enigma came to a halt.


Enigma codebreaking with the computer

From the late 1970s on historians became more and more interested in the Enigma. It turned out that this machine had influenced the course of WW2 in a considerable way. The Enigma now also got into the focus of cryptology experts. In 1995 Jim Gillogly, a reader of this blog, described a new computer-based ciphertext-only attack on Enigma messages.

In 2004 Frode Weierud and Geoff Sullivan, two more readers of this blog, started a project named “Breaking German Wehrmacht Ciphers“, in the course of which they solved hundreds of original Enigma messages from the Flossenbürg concentration camp and Hitler’s Russia campaign. Earlier this year, Frode Weierud and Olaf Ostwald published a paper titled Modern breaking of Enigma ciphertexts in the scientific magazine Cryptologia. This article reports on further improvements in Enigma codebreaking with modern means.

In 2006 musician Stefan Krah along with hundreds of supporters, who provided computer capacity, cracked three World War II enigma codes.

Michael Hörenberg, a teacher from Southern Germany, and Dan Girard have been very successful in breaking Enigma messages, too. Michael’s website renders a lot of interesting information about his and Dan’s codebreaking activities.

All in all, breaking Enigma messages has made considerable progress in the last 15 years. Not only have computers improved, but Enigma codebreaking algorithms have also become more and more sophisticated.


The Cipher Event

On Friday, April 7, Enigma codebreaking experts will have the chance to proof their abilities. The HeinzNixdorf MuseumsForum (HNF) in Paderborn, Germany, and the Bletchley Park Museum in UK (Bletchley Park is the place where the British broke the Enigma) will organize a cryptographic puzzle game they call Cipher Event (thanks to Karsten Hansky, Roland Wintgen, Ralf Bülow, and Tomtoo for the hint).

Starting at 9 a.m., the HNF will send radio messages that are encrypted with an original Enigma. Radio amateurs are encouraged to listen to these messages (40m, 7036 kHz, DL0HNF) and to write them down. Codebreaking experts in Bletchley Park will try to decipher these cryptograms with a Bombe (as no original copy of this machines has survived, a rebuild will be used).

In addition to the codebreakers in Bletchley Park, other Enigma experts are invited to break the radio messages coming from Paderborn. I am sure, some of the Enigma deciphering specialists mentioned above will take part in this challenge. They will probably be a lot faster than the guys in UK, as they will use computers instead of WW2 equipment. If you have deciphered one of the messages, send the solution to enigma(at)hnf.de.

If you happen to be in Paderborn or Bletchley Park, you can watch the sending or breaking activities onsite. Otherwise you have the chance to follow the live stream on the HNF website.

One of the purposes of the Cipher Event is to honor Alan Turing, who was the mastermind of the Enigma breaking in Bletchley Park. If you want to meet Alan Turing’s nephew Dermot Turing, you should come to the Euro HCC in Bratislava. Dermot will give a keynote speech there.

Further reading: The mystery of the Soyuz files

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Kommentare (18)

  1. #1 Klaus Schmeh
    5. April 2017

    Bart Wenmeckers via Facebook:
    Ha this is cool

  2. #2 tomtoo
    5. April 2017

    It’s in some way unfair. But it realy interests me how much faster we are now ?

  3. #3 Jerry McCarthy
    England, Europa
    6. April 2017

    #2. The folks at BP will be using the Turing-Welchman Bombe rebuild “Phoenix” which is a mechanical replica, as close as it can be, to the original “Bombe”. As such, therefore, the speed is likely to be quite close to the original.

  4. #4 Jerry McCarthy
    England, Europa
    6. April 2017

    Anybody who might like to run a parallel system could try the software-based Bombe emulator to be found at: https://www.lysator.liu.se/~koma/turingbombe/

    I understand that a crib and the Wheel Order will be published at the time of the transmission, if not before.

  5. #5 Jerry McCarthy
    England, Europa
    7. April 2017

    BTW, the two four-rotor Enigma pictures at the head of this page are somewhat inappropriate for this exercise!! 🙂

  6. #6 c2
    7. April 2017

    sha512(DECRYPTEDMESSAGEWITHOUTBLANKSANDINCLUDINGXANDY) = 0a6b9b5ed28ac05de69c740c800321a60967a6ccf7ab95b936260399e46bdc1564f3ebf4dd25216fccafa23ffd6f8b1620380c7f20d6500ca464b1296c52b245

  7. #7 George Lasry
    8. April 2017

    Has anyone got the ciphertext?

  8. #8 Dan Girard
    9. April 2017

    #7: I missed the event as it happened, but I was able to find these afterwards in the YouTube video of HNF’s live stream:

    The message to be broken with the Turing Bombe and a crib:

    000 HNC FVW

    The crib for message 000:


    The message to be deciphered to show that the key of the day had been found:

    001 HNC VBY

    Two additional messages:

    002 HNC LTZ

    003 HNC YJL

  9. #9 Klaus Schmeh
    9. April 2017

    @Dan Girard:
    Thanks for sharing. I was looking for the ciphertexts but I couldn’t find them anywhere.

  10. #10 George Lasry
    9. April 2017

    Thanks Dan!
    This was a very easy problem, with such a long crib, and no slow rotor turnover :-), compared to what you (Dan) and other experts (Michael, Olaf) are able to do with much more challenging messages/settings (and even for a casual amateur like me).

    Still, good publicity for both the Heinz Nixdorf Museum and for BP.

  11. #11 Klaus Schmeh
    9. April 2017

    Apparently, the guys in Bletchley Park were successful in breaking the Enigma message. Did anybody else try? As indicated in my article, it was expected that Enigma enthusiasts using computer programs would be faster.

  12. #12 George Lasry
    9. April 2017

    I did. As I wrote, that was an easy case. There were 2 middle rotor turnovers, but the first was after 20 letters, which is more than enough for a simple Turing Bombe run.

  13. #13 Klaus Schmeh
    9. April 2017

    >I did.
    So, you used the Bombe method, not Hill Climbing, right?

  14. #14 George Lasry
    9. April 2017

    Yes, a Bombe program which I wrote. It can also handle movements of the middle and left rotors.

    Hill Climbing would have been tough, as the messages were < 60. For that you need the more sophisticated method developed by Olaf (recent Cryptologia paper).

  15. #15 Dan Girard
    10. April 2017

    I tried message 000, both with my own Bombe program and with Magnus Ekhall & Fredrik Hallenberg’s emulator that Jerry McCarthy recommended, which I’ve tried a few times before.

    Though mine was faster, I found theirs to be more enjoyable. It allows you to re-create the whole process of decryption with the Turing Bombe, from the drawing up of the menus and the plugging up and running of the Bombe, through the checking of the stops with the Checking Machine, to completing the solution by trying to decrypt the message on an Enigma simulator, adjusting the ring settings and adding additional steckers as needed.

    My compliments to Magnus and Fredrik, both for their fine emulator and for the superb tutorial that explains clearly how to use it (and to which I understand Jerry also contributed).

  16. #16 Jerry McCarthy
    England, Europa
    10. April 2017

    #15. Yes, that was me; however, my contribution was trivial compared with the main job work.

    I have found that the work, which you apparently enjoyed, of plugging up the Bombe, is perhaps a little long-winded, so I have been thinking about maybe writing a small add-on to generate the wiring file which the emulator would then read.

    Haven’t quite gotten around to it, though 🙁

  17. #17 Magnus Ekhall
    10. April 2017

    #15: Thank you for your kind words on the Bombe simulator.

    #16: I sometimes cheat and write the input file manually rather than connecting the menu through the GUI. As you say, it is a bit long-winded.

  18. #18 Rainer Zufall
    12. Juni 2017

    @Dan Girard: Thanks for the messages.

    @Magnus Ekhall: Thank you for the Bomb-Simulating-Software.

    I still have a question about the key of the day. I have found the message key from the message 000 with the simulating software. How can I find now the key of the day?

    Thank you and best regards