NobodySpecial October 10, 2013 1:25 PM

@Shachar – but how do you know that doesn’t have a backdoor?
Who controls the paper industry ????

Figureitout October 10, 2013 5:55 PM

Very nice, is one of my favorite sites. Beautiful board layouts, and just one of the many things you can do w/ arduino. I’m going to make a morse keyboard real soon. Reminded me of NAND ‘Puter lol. So intense.

Clive Robinson October 11, 2013 4:49 AM

A fun thing to build if you’ve got a few days spare or a well stocked workshop. Not as nice to look at as that beautifully built “artwork” Enigma Bruce posted about a few years back, it realy was an eye-catching conversation piece.

However if I was doing this project for “kids to build” I’d cut down on a lot of the wiring and use a serial drive LCD for the “rotor window” and an old PS2 or earlier IBM keyboard and leave out the stecker board so they could get it up and running before bordem kicks in. Then get them to build the letter lights, keyboard, stecker board and nixie-tube style display as sub projects.

I might even go a step further by mounting rotory encoders under the rotor displays pointing side ways to mount flanges similar to that on the real Enigma rotors.

@ Figureitout,

Many moons ago (around 430 of them) I had to design and build the first of several “serial ALU” with PROMs to hold the basic microcode computers (glorified state machines). I used a mixture of NAND NOR and XOR gates and a couple of latches and counter chips to do it. It’s primary purpose was to read in serial data transcode it and push it out as either serial or parallel data. The important part was it had to fit in a diecast aluminium box around 8x16cm and be not just IP67 but “marine proof” as well. It took a week to design and “layout” with tape and get the boards made over the weekend and back early the next week to debug correct (Kraft-knife programing) and write the microcode sequencer. Several varients followed, and as far as I’m aware some are still running in plant today.

The reason to apparently “do it the hard way” and not use say a 74181 was space saving… That 4bit ALU or any of the “real CPU’s” of the time needed way to much space as they were in 0.6in wide 40pin DIL packages and ROM and RAM were in 24pin 0.6in DIL as well then there were the clock chips glue logic etc etc…

These days you’ld pull down a PIC chip a bit of perf board a few res/cap and a packet of epoxy filler, “refactor software” (ie cut-n-paste the code together from your personal library of code 😉 and be done in time for tea…

Aspie October 11, 2013 5:23 AM


The charlieplexing, though, should be able to address 132 LEDs with 12 pins – though the circuitry would be a bit of a ‘mare. A nice touch could be to swap the 7-segs for nixie tubes to give it that retro cold-war look.

Richard H October 11, 2013 5:25 AM

@Clive Robinson
is “marine proof” the naval version of “squaddie-proof”, or does it refer to Pussers’ Rum?

phred14 October 11, 2013 6:30 AM

FYI, I’ll likely see an Enigma tomorrow morning. I’m heading to the NEAR-Fest in Deerfield, NH, which happens Spring and Fall every year.

Somewhere on the one of the many tables, there is usually (Always, that I’ve seen.) some guy showing his Enigma machine. I don’t know if it’s original/restored or a replica – I guess I should look more carefully. Either this guy or someone like him also shows up at “Flea at MIT”, third Sunday of every month, April through October.

Figureitout October 11, 2013 11:27 AM

Clive Robinson
These days…
–Yeah, that’s the big gripe w/ arduino and older developers that had much harder work. Now, it’s so easy.

Derek McRiner August 5, 2016 4:19 AM

Hi Bruce,

I had great fun building and using the paper enigma machine to verify already decoded messages on Dirk Rijmenants website The enigma Challenge.

It has been said that an enigma machine could have a modern day “key” as high as 82. It wouldn’t have gone unnoticed that, even though it is a facsimile of the real machine, a paper enigma could have as many rotors as you like (within practical reason) if the tube were extended, greatly increasing the possible combinations of letters. Couple this with revised daily coding sheets, would you agree that the key would be much higher?

I haven’t tried this myself but I believe it would be interesting to work out the modern day equivalent security key with, say six rotors (plus the reflector of course).

Kind regards,

Derek McRiner

Clive Robinson August 5, 2016 4:56 AM

@ Derek McRiner,

I believe it would be interesting to work out the modern day equivalent security key with, say six rotors (plus the reflector of course).

It realy does not matter what the key size is with the Enigma. Due to design defects (the reflector, odometer stepping) it is vulnerable to a “known plaintext” attack.

During WWII the UK got their “known plaintext” by “knowing the enemy” from the over stylized message format and what we now call “traffic analysis” as well as a significant “card index” they built up, hence the term “British Museum attack”.

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