Using the hint decoder
Paste the hint as it appears on the cache page, letters scrambled. The decoded hint appears underneath as you type. Anything inside square brackets is copied across untouched, so `Ybbx haqre gur [Big Rock]` comes out as `Look under the [Big Rock]`, not `[Ovt Ebpx]`.
ROT13 undoes itself, so the same box scrambles too. Type the hint for your own cache in plain English and the output is ready to paste into the listing. The Brackets setting turns the bracket rule off, for a hint that was scrambled whole.
Nothing you paste is sent anywhere. The decoding runs on your phone, and once the page has loaded it keeps working with no signal at all.
How ROT13 works
Each letter moves 13 places along the alphabet. A becomes N, B becomes O, and N wraps round to A. There are 26 letters, so moving 13 twice lands back where you started: one step hides the hint and the same step reveals it.
Digits, punctuation and accented letters pass through unchanged. A hint like `Fgrc 4` decodes to `Step 4`.
It isn't meant to keep anything secret. It stops your eye catching the answer while you read the description, and anyone who wants the answer can have it in a second.
Why some words sit in brackets
Some hints mix the two: most of the text scrambled, a word or two left readable in square brackets. Run that through a plain ROT13 tool and the readable part comes out scrambled instead, which is the mess this page avoids.
A closed pair of brackets is treated as a fence. An opening bracket with no closing one is just a character, and everything after it is decoded as normal. If a hint still reads as nonsense, it may use a different shift or a different cipher. Paste it into the cipher identifier, or see the cheat sheet on the geocaching puzzle solver.
Older than geocaching
ROT13 was in use on Usenet's net.jokes newsgroup by the early 1980s, hiding jokes some readers wouldn't want to see and the answers to puzzles. Newsreaders grew a key to flip a post back. Geocaching, which began in May 2000, borrowed the same courtesy for hints: the answer is there, one deliberate step away.
Questions
Why does my hint still look scrambled?
It may not be ROT13. Some owners use another Caesar shift, Atbash, or a cipher with a key. The cipher identifier tries the common ones and ranks them by how much each reads like English.
Can I scramble the hint for my own cache?
Yes. Type it in plain English and copy the result. Put any word you want left readable in square brackets.
Does it work without signal?
Yes, once the page has loaded. The decoding happens on your device, so nothing needs to reach a server.
Is ROT13 secure?
No. It's a courtesy, not a lock. Anyone who knows the trick can read it, which is the point for a hint.
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Sources
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