How-To: Mysteries & Double Decryption

Mystery Caches are like geo-sardines. Either you love them or hate them. And they’re everywhere. Very likely, you know someone who is good at mystery caching.


If you want all smileys here you’ll have to deal with them.

Mystery caches (formerly ‘Unknown’ caches) appeal to that next-level geocacher. They add another level of hiddenness to the hunting experience. They grant giant asterisks of satisfaction to the find.

Dealing with a new mystery cache on the map can be a daunting challenge. The scenario typically goes like this (for me anyway):

  1. Open listing
  2. Exhale aggravatedly
  3. Decrypt the Hint, if any
  4. Read listing
  5. Scratch head
  6. Try a few things that worked with other mystery caches

If that doesn’t yield something like an answer or a breadcrumb along the path to a solution, then it’s common to close the listing and try again another day/month. What drives many players up the wall, this author included, is when a mystery cache doesn’t lend any help along the way to a solution.

Veteran mystery cachers know it’s that breadcrumb which is the hallmark of a good mystery cache.  A good mystery cache will give the solver at least one ‘a-ha!’ moment, reeling them in toward the final, or the next portion of the puzzle.

Since the ‘solving’ of a puzzle for coordinates can mean translating from one kind of information to another, mystery cache hiders regularly use Encryption to create something that must then be Decrypted.


A Breadcrumb Around the Corner

A coworker of mine is a fellow geocacher, who one day was getting off the boat while I had to stay and work the next two weeks.  He knew I was working on crafting my own Unknown Cache for the geo-map, and he decided to leave me a cryptic message to have a little fun with me.

01010010 01001001 01001100 01001010 01000001 00100000 01001000 01011010 01000010 00100000 01010100 01000110 01000001 00100000 01010010 01011010 01000110 01011000 01001100 01010011 01001101 00100000 01001100 00100000 01010010 01001100 01001010 01001010 00100000 01010001 01000001 00100000 01010000 01000110 01001100 01010011 01011000 01001100 01010011 01001101 00100000 01010001 01000001 01000001 01000110 00101110 00100000 01011001 01010101 01010100 01001000 00100000 01011001 01010100 01000100 01000001 00100000 01010100 01010011 01010000 00100000 01001100 00100000 01010010 01001100 01001010 01001010 00100000 01011001 01000001 01000001 00100000 01001000 01011010 01000010 00100000 01011001 01011010 01011010 01010011 00101110 

Well, I didn’t quite know how to answer that. But I did know what I was looking at.

The idea here is that the letters you see on the screen in front of you aren’t really there. The computer that houses this page has a packet full of 0’s and 1’s that your web browser turns into letters to make this page.  It’s called binary data.

There are several websites that converts binary data into alphanumeric data. Here’s a good example of one.

Once translated, you get:


That’s one layer down.  Because we’re definitely on to something here.  This is the Breadcrumb effect.  The solver has attempted and achieved something that tells them Yes, you’re on the right road.  So many good Mystery Cache puzzles miss this important feature.


Substitute Teacher

RILJA HZB TFA RZFXLSM L RLJJ QA PFLSXLSM QAAF. YUTH YTDA TSP L RLJJ YAA HZB YZZS.  What this looks like is a sentence with the letters all wrong.

There are a couple of approaches here. If you’ve spent any time with the Hints portion of geocache listings you’re familiar with Rotation Ciphers.  The letters of geo-hints are typically rolled forward by 13 letters.  A becomes N, B becomes O, etc.  So, naturally, that was my first avenue of exploration.


We hit the Decrypt link so fast we rarely see the Key on the right side.

To our dismay, translated in ROT-13 (rotated forward 13 letters) ‘RILJA‘ becomes ‘EVYWN.‘  So that’s not it.

Next, we explore whether it’s a rotation cipher, but not 13 steps.

ROT-14 yielded FWZXO, ROT-15 gave us GXAYP, ROT-16: HYBZR, so on and so forth.  I’ll spare you the legwork here.  Nothing of consequence came up for rotation ciphering.

This is when you step back and look at it with one eye closed.  Do you see the letter L by itself?  How many words in English have only one letter?  There are two: ‘a’ and ‘I.’

This is a Substitution Cipher.  The letters are actually other letters, and there’s a pattern to it all.

So, that letter L by itself is a vowel, either ‘A’ or ‘I.’

Look also at ‘YZZS.‘  There is a super-high probability that Z is also a vowel.  If so, it’s very likely an ‘O’ or an ‘E.’  Then there’s ‘QAAF’ at the end of the first sentence, and again, that letter ‘A’ is probably substituted for another vowel. Also there’s a ‘QA‘ which is going to be a two-letter word ending in a vowel.  So, He, To, Be, We, No… There aren’t many likely ones but they’ll help you figure out what’s the right one.

Take what you suspect to the other words with those letters, like ‘YAA‘ and see if your vowel fits into any words which could be there.  Unless my friend was trying to tell me something that had the word MOO or POO in it, which wasn’t likely, ‘A’ wasn’t ‘O,’ but ‘E.’

This is when you realize you’ll need to make a list of letters on one margin and a list of what they’re substituted for, on the other margin.

I like this puzzle because it has breadcrumbs the whole way down.  Once you figure out ‘YAA’ is ‘SEE’, YZZS becomes ‘SOO_’ and then you have to realize ‘S’ is ‘N.’ (Unless he wanted to tell me about SOOT which is possible, but again, not likely.


Thanks a lot, bro.  All this so he could goad me about having to work while he was out having fun.  He could have at least told me he was out finding caches without me.


Moral of the Story

If you’re going to craft a mystery cache puzzle, especially one with more than one level of difficulty, remember: Leave a Breadcrumb.  The last thing you want is for your neighborhood FTF-hound to give up trying to figure out your mystery cache.