Arduino-based Enigma Replica is Fully Functional


This open-source Enigma replica by the folks at [ST-Geotronics] is simply stunning. They drew their inspiration from a hilarious build we saw a few years ago that hacked a children’s toy into an Enigma machine. Their project is instead modeled on the original Enigma M4 cipher machine, and aside from a bit of artistic license, we think they nailed the visual style. As for functionality, the guide claims everything works, right down to the plugboard.

Rather than try to immediately cram everything into the final enclosure, the [ST-Geotronics] gang painstakingly worked out a prototype to be sure the four 16-segment LED displays had been wired correctly and functioned properly. The next step was laying out a swarm of buttons and resistors on a 6″x8″ perfboard. They used charlieplexing to handle the 16-segment displays (which actually have 17 LEDs each), and deceptively disguised each display as a nixie tube by mounting them vertically and encasing them in a transparent dome. The case follows the M4’s original dimensions and consists of a plywood box with scrap steel for the top plate.

Swing by their Instructables page for more details. There you can find several Arduino sketches to test functionality and the code for five different M4 operation modes.


  1. macona says:

    All that work and he sticks it in a box made from generic hardware store plywood. C’mon man!, it deserves better! At least baltic birch plywood.

  2. JustMe says:

    Arrrggg! If one has the need to replicate an Enigma machine, do it at least the same way it was in the old days => mechanical wheels, NO FREAKING ARDUINO. There are enough Enigma emulators around, the beauty of the machine was that there WASN’T a chip inside, because the nazis haven’t had any!

  3. Hirudinea says:

    HOLY SNAPIN’ CRAP! That thing is a thing of beauty! Somebody please build one using an old typewriter, nixie tubes and brass engraved plates (mit Deutsch natürlich) and it would be da Bombe! (Look it up.) Oh and here’s a link to the crypto museum page on the Enigma, including a simulator, so if you do build one you can test it without building another one.

  4. Hirudinea says:
  5. grayfox386 says:

    it would of had a much more Authentic vintage look to it if you had used a numitron tube in place of the lame led displays

    • Marc says:

      grayfox386, You are absolutely right! Numitrons are way cooler (and now that we know they are low power, we could use them) but, do they exist in 16-Segment? Or 14-Segment would also do… 7-Segment just can do the whole alphabet properly…

  6. pcf11 says:

    This should have been a fail post because the Enigma was one of the greatest fails in history. The boys at Bletchley would joke that they were reading the messages before the Germans were. Often they were probably right too.

    • Sheldon says:

      Except the Enigma machine wasn’t the fail – it was the German’s use of it (i.e. operator error). If it had been used correctly it would have been significantly harder but if it hadn’t been for some operators using the same start/end-messages or repeating text in their message then the Bletchley teams would not have had a cypher-key to begin their searches to decode the entire message.

      • pcf11 says:

        Pads were one in the code breakers used, but it was not the only failure. The greatest failure was total German confidence in the Enigma. Blind faith is never a good thing.

  7. JuMP says:

    That is not charlieplexing at all… Just plain multiplexing. See

    • SofS&T says:

      Good catch. As the more often than not silent partner in S&T you are right they are multiplexed. I am impresed that you noticed. Multiplex is just a little simpler to code as we only deal with two states of logic high or low. It also lets us drive the common annodes easily with a p chanel mosfet. This allows more current hense a brighter display while observing the rated maximum current limitations of the atmega 2560.
      To truly “charlieplex” requires three state logic high, low, and open. to achieve the open the pin mode needs to be changed from output to input thus releasing the 2560’s internal pull up and pull down circuits. True charlieplexing would have saved us 7 pins however We did not feel that it was aproperiate to sink the annodes of up to 17 leds to one one io pin. Thanks for the correction ROCK ON!

  8. kerimil says:

    cool but don’t you think it’s a bit inapropriate to post german/nazi related stuff on hackaday ??

    • kerimil says:

      what’s next? building a replica of a gas chamber for jews with angela merkel??

      • vpoko says:

        This may be the dumbest comment I’ve ever read on HaD, and that’s saying something. It’s technology that’s very interesting within the context of history, so no, it’s not inappropriate for HaD. You can’t study the history of cryptography and cryptanalysis without including the Enigma, unless you want to censor your own knowledge. That’s not remotely the same as giving approval for how it was used. The device itself is not good or evil, so it can be studied independent of its use.

        • kerimil says:

          naah it’s not a dumb comment… I am just trolling all of those who write ‘nazi concentration camps’ instead of ‘german concentration camps’… I am just making sure you realize that the grandfathers of the guys who made your BMW gassed jews 70 yrs ago

          • vpoko says:

            So what? Someone’s not responsible for what their grandfather did. Everyone only has to answer for themselves.

          • pcf11 says:

            They were Nazi concentration camps as most Germans were not involved. We can sit here today and say but why didn’t they know, but when the aliens come down to rescue their brothers in area 51 I’ll ask you then why you didn’t know.

          • vpoko says:

            I hope I’m misunderstanding, because it sounds like kerimil holds a grudge against Germans today for something that happened before they were born. Of course that would be ridiculous, so I must be misreading it.

      • pcf11 says:

        Based on the intelligence of your comment I assume you took the blue pill. The gas chambers themselves were not particularly interesting. The crematoria on the other hand is patented technology (No. 861,731). The official patent document’s title is “Process and Apparatus for Incineration of Carcasses, Cadavers and Parts Thereof.” They ran on rendered fat once stoked. But it isn’t a totally new idea really, Nero used Christian torches in his garden. The Yes Men revived the idea for their human candle prank too. Based on the reception that garnered you may yet live to see the day where the term human resources is literally interpreted too.

        Power from the people!

  9. Oh wait. THAT’S why they called him Neo in the Matrix! … ; )

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