It’s not like I’m pro-Nazi, please understand, but I am an unabashed supporter of their Enigma machine. It should have worked. It would have been infallible, if only …
Anyone who has ever worked a cryptogram puzzle in a crossword magazine knows how easy it is to crack a simple alphabet-substitution cypher. You pick out common words like “the” or “a” and with a little patience you’ve worked out the whole code. Of course, the longer the message, the easier it is to decipher. If you’ve got a full paragraph to work with and it’s stocked with common small words, it’s usually quite easy. If it’s only a word or two, it’s nearly impossible .. unless you have another snippet of code with the same substitution scheme to compare it to.
Which leads us to the genius of the Enigma:
First, they designed it like an electric typewriter. But instead of hooking the “S” on the keyboard up to the letter “S,” it was randomly assigned to another letter, say “V.” So the person sending the message was able to type it at normal speed and what came out was the encrypted code. Before computers, this was an amazing breakthrough. Even better, the recipient merely had to type it out on his end and the uncoded message just appeared.
At its heart, it was still a substitution cypher, which could have been broken … until they added the “tumblers.” These doodads changed the connection from the keyboard to the typed letter with every keystroke. So if you typed SSS, what came out might be VKU.
Imagine trying to crack a substitution code where every letter used a completely different code!
Like I said, genius. And they made it very easy to reset the tumblers, so that every day they started with a fresh, random code. The Germans developed instruction books for everyone with an Enigma machine to show them how to set it up each morning so that everyone in their message chain would have the same coding structure each day. Thus, the Allies had to begin cracking codes each morning with absolutely no prior messages to help them out.
The men who approved the Enigma were experts at cryptography and knew exactly what the Allies would be looking for in cracking the codes, so they also mandated a few simple rules for the people sending the messages: never repeat phrases; try to avoid overuse of common words; avoid using people’s names unless absolutely necessary.
And this is where it falls apart because, unfortunately for them, the people sending the messages didn’t know or care about rules of cryptanalysis.
Some general got the idea to send weather reports each day, just after dawn. As soon as the Allies realized this, they started looking for the words “cloudy” and “rain” and bada-bing they had their first clue of the day handed to them.
My favorite of the misuses comes from the telegraph guys themselves, stationed far from home, feeling like a small component in the scheme of things. They had to send a quick test phrase each day to their sending/receiving counterpart, to make sure everyone’s machines were in sync. These were supposed to be random words pulled from a dictionary, but instead they got in the habit of using the name of their girl back home, or their hometown. It took the Allies a bit longer to catch onto this, but once you find out that the bloke on the 6 am shift is starting every day by piningly typing “Frau Gisela,” you’re well on your way to cracking every code he sends from there on out.
Now, I’m not saying that any of this was easy for the Allies. If they hadn’t gotten their hands on a working Enigma machine after seizing a submarine, they may never have figured out a single message. And I’m not trying to take anything away from Alan Turing (the man credited with cracking the Enigma by building the world’s first computer, A.K.A. the geek’s dreamboat).
But it is amusing to realize that the Nazis couldn’t even get their own army to follow simple procedures about sending top-secret messages. People have to find ways to be individuals, and that usually means breaking rules.
Or, to look at it another way:
The world is shaped by people taking shortcuts because they’re certain their way is “good enough.”