Decoding Enigma Using A Neural Network

[Sam Greydanus] created a neural network that can encode and decode messages just as Enigma did. For those who don’t know, the Enigma machine was most famously used by the Germans during World War II to encrypt and decrypt messages. Give the neural network some encrypted text, called the ciphertext, along with the three-letter key that was used to encrypt the text, and the network predicts what the original text, or plaintext, was with around 96-97% accuracy.

The type of neural network he used was a Long Short Term Memory (LSTM ) network, a type of Recurrent Neural Network (RNN) that we talked about in our article covering many of the different types of neural networks developed over the years. RNNs are Turing-complete, meaning they can approximate any function. [Sam] noticed the irony in this, namely that Alan Turing both came up with the concept of Turing-completeness as well as played a big part in breaking the Enigma used in World War II.

How did [Sam] do it?

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VCF East: Enigma Machines In The Flesh

At the end of World War II, the Germans ordered all Enigma cipher machines destroyed. Around the same time, Churchill ordered all Enigma cipher machines destroyed. Add a few decades, neglect the efforts of Polish codebreakers, and make a movie about Alan Turing and an offensively historically incorrect love interest, and you have a mystique around these rare, innovative cipher machine.

At the Vintage Computer Festival East, I was privy to what is probably the largest collection of Enigma machines on the planet. The exhibit comes from [Tom] and [Dan Perera] of Enigma Museum. Right now, they’re they only place where you can go out and simply buy a real, wartime Enigma machine. The price? Well, there is a pair of million-dollar Apple I boards at VCF. The Enigmas go for about a fifth of an Apple I.

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3D Print An Enigma Machine That’s Close To The Real Thing

The Enigma machine as used by the German military during World War Two exerts a curious fascination among our community of hardware hackers and makers. Perhaps it is the mechanical complexity of the machine itself, or maybe the tale of how its encoded messages were decrypted by Allied codebreakers that contributes to this interest, but whatever it is we’ve seen a succession of Enigma-related projects over the years that shows no sign of abating.

The latest Enigma project to come our way is a particularly nice one from a group of first year students at CentraleSupélec Rennes, in Northwestern France. Their Réplique Enigma is a fully mechanical Enigma replica using 3D printing techniques, and unlike so many replicas which use modern electronics it has a set of rotors just like those you would have found in the original. The rotors themselves have a 3D-printed plastic shell which houses brass contacts and the associated writing, while the keyboard and lamp board are both made from plywood. Rather than trying to replicate the original switches from the keyboard they are using modern microswitches, however the keys themselves are upright posts that resemble the original. An AZERTY layout may not have been present on the real Enigma machines, but lends a pleasing twist to the build.

It’s worth browsing all the pages for this build, as the front page does not necessarily capture the whole build. The rotors set this Enigma apart from many of the replicas we’ve featured in the past, so you may find it interesting to take a look and make a few comparisons.

Paper Enigma Machine

It was high-tech encryption for an important period of time in the mid-1940s, so perhaps you can forgive us our obsession with the Enigma machine. But did you know that you can make your very own Enigma just using some cut out paper strips and a tube to wrap them around? Yeah, you probably did. But this one is historically accurate and looks good too!

If you just want to understand how the machine worked, having a bunch of paper rolls in your hands is a very intuitive approach. Alan Turing explained the way it worked with paper models too, so there’s no shame there. With this model, you can either make the simple version with fixed rotor codes, or cut out some extra slip rings and go all out.

What is it with Hackaday and the Enigma machine? Just last month, we covered two separate Enigma builds: one with a beautiful set of buttons and patch cables, and another in convenient wrist-watch format. In fact, one of our first posts was on a paper Enigma machine, but the links are sadly lost to bitrot. We figure it’s cool to repeat ourselves once every eleven years. (And this one’s in color!)

Enigma Machine Wristwatch

We don’t find smartwatches to be supremely usable yet. This one sets a definition for usefulness. The Enigma machine is of course the cipher process used by the Germans during World War II. This Enigma Machine wristwatch is not only functional, but the appearance is modelled after that of the original machine. With the speckled gray/black case and the Enigma badge branding [Asciimation] has done a fine job of mimicking the original feel.

Driving the machine is an Arduino Pro Mini. We’ve seen Arduino Enigma Machines in the past so it’s not surprising to see it again here. The user interface consists of an OLED display at 128×64 resolution, three buttons, with a charging port to the right and on/off switch on the left.

The device is demonstrated after the break. Quite a bit of button presses are used to set up each of the three encoder wheels. But that’s hardly avoidable when you’re not committing to a full keyboard. We’re pretty impressed by the functionality of [Asciimation’s] interface considering it’s hardware simplicity.

This seems perfect for kids that are proving to have an interest in engineering. They learn about ciphers, embedded programming, and mechanical design and crafting (this is a hand-sewn leather wristband). Of course if you build one and start wearing it into the office we won’t judge.

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Here’s something that’s just a design study, but [Ivan]’s Apple IIe phone is a work of art. You’re not fitting a CRT in there, but someone out there has a 3D printer, an old LCD, and a GSM module. Make it happen. See also: the Frog Design Apple phone.

A few days ago we posted something on an old ‘286 machine that was able to load up the Hackaday retro site. For a few people, this was the first they’ve heard about our CSS and Javascript-less edition designed specifically for old computers. They dragged out some hardware, and [WTH] pulled up the site on a Dell Axim.It’s actually somewhat impressive that these machines have SD cards…

[Arduino Enigma] created a touchscreen Enigma machine. Why haven’t we seen an Arduino Colossus yet?

The crew at Adafruit now have a Flying Toaster OLED, which means we now have flying toaster bitmaps for all your OLED/graphic display projects.

[Ian] had an old rackmount programmable voltage standard. This was the remote programmable voltage standard, without front panel controls. No problem, just get an Arduino, shift register, and a few buttons. Video right here.

A few months ago, [Jan] released a neat device that stuffs a modelling synth inside a MIDI plug. He’s selling them now, and we’d love to see a few videos of this.

Hackaday Links: March 9, 2014


Thinking about starting a CNC machine, 3D printer, or laser cutter project? Misumi has you covered. They’re offering up $150 worth of free stuff with a coupon code. [CharlieX] is putting together a BuildLog laser cutter, a whole bunch of people on reddit are building 3D printers, and I have most of the rods for an i3 build. Just use the promotion code First150 on your order. Actually, read the terms and conditions, but rest assured – this is legit.

A few months ago, we saw this Enigma cypher machine that combines the classic late-30s aesthetic of the original with modern hardware – including a few 16-segment displays. Now there’s a Kickstarter for the Open Source Enigma replica, and it looks like it’s going to end up being pretty popular. Here’s the site with all the deets. Check out that QWERTZ keyboard.

[Jason] has a love of LEGO and a terrible keyboard. Combine the two and he came up with a functional LEGO keyboard. The electronics are, sadly, an old PS/2 membrane keyboard, but the mechanicals are a work of art – all the keys are mounted on a grid of Technic parts that can be positioned over each of the membrane buttons.

Want a really cool look for your next enclosure? How about LED pipes? They’re those clear plastic bits that direct the light from LEDs around corners and can make any enclosure looks like a Star Trek set piece. You can cut these things with a laser cutter like the Alima team did with their indoor air quality meter. Looks pretty cool.