Have any Nazi codes you need broken?

I don’t get to find geocaches very often but whenever we plan to leave the house that doesn’t stop me from pulling up the database on Geocaching.com and seeing if there are any near where we’re headed. No matter the true purpose of our death march to the mall that weekend I always know where the closest geocache is in case I can somehow steer our path in that direction.

Between geocaching opportunities I spend a lot of time thinking about geocaching, listening to geocaching podcasts, watching geocaching videos, and planning expeditions that’ll probably never happen; I like to be prepared. I like to pour over the webpages of possible future targets so that, should I get to search for them, I’m already familiar with just how horrified I should be with the amount of poison ivy surrounding a potential find.

A new kind of geocache has crept into my consciousness as of late and even though I already knew of its existence, only now have I realized its potential. There are many types of geocaches, the most basic being a container hidden somewhere in the world with its actual latitude and longitude posted online. Another kind, a more involved kind, is the puzzle geocache (or the mystery cache as it’s technically called). It’s not actually located at the coordinates posted online, although by rule it has to be within two miles of those coordinates.

Puzzle caches require you to solve some mystery, crack some code, or divine some hidden clue in order to reveal the geocache’s true location. Sometimes that means arriving at a location and using real world objects like the text of a history marker to fill in gaps of a broken set of coordinates. Or sometimes it’s as crazy as the puzzle cache I recently solved, which involved downloading a tri-colored, Rothko-esque image, and then determining each color’s RGB code. Colors displayed on your computer have what’s called a RGB code (red, green, blue), a set of numbers that determine the color’s exact shade. If you ever work with graphic designers it’s something you might discuss with them (and if it wasn’t for my job I’m not sure I would have solved this one). Ultimately that puzzle cache’s image’s RGB codes revealed the coordinates for the geocache. Very clever.

My descent into puzzle caching began a few months ago when we were out of town visiting my family and with a few minutes to burn, I did what I always do; I looked online for nearby caches I hadn’t yet found. On this trip there wasn’t going to be time for any geocaching but I figured I could make a list of interesting caches for a future visit. This time, for some reason, in my search I didn’t filter out non-traditional caches like usual and it was then that I saw the puzzle cache symbol hovering over an odd spot on the map: The German Restaurant. The restaurant has a name but my family always just calls it The German Restaurant. We tend to go there when we’ve got a large group in town or when there’s a special occasion to celebrate. The food is terrible and the beer is always kinda warm, but the atmosphere is top notch. We usually go on nights when their band of old German men are playing accordions and singing old German anthems loudly and drunkenly.

Intrigued, I dove deeper, particularly after seeing that the puzzle cache had a 5-star difficulty rating. The whole description page was written in German. Craftily, the main puzzle elements weren’t text on a page but text written into image files so it couldn’t be copy-and-pasted into Google Translate. The cache page included two images, one that looked like a letter with a message written in cipher at the bottom and one that seemed to be a key to solving the cipher.

Coded letter and cipher posted to the puzzle geocache

Turns out that running the puzzle’s text through Google Translate wouldn’t have worked anyway. It was written in Sütterlin, a defunct form of handwriting that was only taught in Germany for a short time, mostly ceasing in the early 1940’s. For American readers, Sütterlin is akin to the stupid and pointless Cursive that’s still taught today. It wasn’t hard to find a Sütterlin alphabet on the internet that would let me translate that scrawl into Latin characters, but doing so by hand, letter-by-letter, over short work lunch breaks was slow going.

After a month or so I finally translated the Sütterlin script and the resulting modern German words. But now came the real puzzle: the cipher. Since solving this puzzle I’ve become a lot more familiar with ciphers and cryptology but in hindsight this cache probably wasn’t the best place to begin. Luck was on my side, however, as by chance I had just (mostly) read Neal Stephenson’s Crytonomicon, a novel of speculative historical fiction that loosely follows World War II codebreakers. (I never finished it. Its content was interesting, its plot wasn’t.)

The main story thread in Crytonomicon was enough to point me in the right direction. I was certain I was looking at an Enigma Cipher. During World War II Nazi Germany used a machine with spinning rotors and an array of plugs to create a pseudo-randomized polyalphabetic substitution cipher (a cipher that uses multiple layers of alphabets) that they thought unbreakable. “Pseudo-randomized” because the process could be recreated, which was necessary for recipients to unscramble messages. To decrypt a code, the code’s recipient, on their own Enigma machine, would duplicate the initial settings of the first machine. The important part of process was letting the recipient know what the initial machine’s setup was, and that’s where that second image on the geocache’s page came into play. German signal troopers had a binder of code keys and would align the Enigma’s rotors and plugs based on today’s date and the “kenngruppen”, a three-digit number hidden within the first five digits of the encrypted text.

The key sheet for the Enigma machine

Sounds complicated? It kinda is (and lazy Germans skipping procedure were a part of how Allied forces were able to break the code). I got REAL deep into the history of the Enigma machine and the various efforts to crack its code every time the Germans changed the device.

This was all well and good, but back to the puzzle cache– how was I going to get my hands on an Enigma Machine and thus reveal the message of this cipher? Why, the internet has all kinds of stuff!

Simulator by Dirk Rijmenants

It took a while. There are actually quite a few Enigma simulators online but many of them are either poorly implemented or were far too assuming. There wasn’t just one Enigma machine, the device was different by German military branch and grew in complexity as the war went on. Many simulators wanted me to tell them upfront what kind of Enigma I was using and I had no idea.

Eventually I found an awesome, downloadable simulator made by a guy named Dirk Rijmenants that came with a thorough and layman-friendly manual. His Enigma simulator is very tactile, having you load the rotors and arrange the plugboard yourself. After some playing around, I loaded the proper settings and it spat out the translated cipher!

Simulator by Dirk Rijmenants

I haven’t looked back since. I’ll never turn away a traditional geocache but puzzle caches are my new love. I’ve got a folder of puzzles I’m working on and keep whichever one is vexing me most pinned up at my desk at work, as if staring at it hard enough will give me the answer.

Now, I just have to figure out when I can find the time to actually go out and FIND the puzzle caches I’ve solved…

In the meantime, anyone have any old Nazi codes laying around that need breaking? I’ve got this new, sorta useless knowledge!


(P.S. If you’re interested in puzzle caches I highly recommend the How to Puzzle Cache book. 90% of solving these isn’t necessarily the puzzle itself but identifying what kind of puzzle you’re actually looking at. The book does a great job of listing many types of puzzles and ciphers.)