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Turning 60: Proof Of Work Mystery Cache

Hidden : 3/20/2019
Difficulty:
4.5 out of 5
Terrain:
2.5 out of 5

Size: Size:   micro (micro)

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Geocache Description:


The container is not at the listed coordinates.

Solve the puzzle below to find the true location.

For my 60th birthday, I offer a puzzle for which you can prove you did the work!

Here's how it works:

  • Go here and enter your geocaching name. You will receive a hash value as 64 hexadecimal digits.
  • The hash is the SHA2-256 (aka sha256) hash of the following string:
    N DD MM.MMM, W DDD MM.MMM XXXXXXX
    Where the D are degrees digits, M are minutes digits, and the X are base-36 digits (a-z,0-9). Note that the string is formatted exactly as shown, including spaces.
  • Your task is to find the string that, when hashed using the sha256 algorithm, results in the hash value you were given. That string is known as a preimage of the hash.
  • The preimage will give the coordinates of the cache and a 7-character token that is unique to your username.
  • When you post your Found It log, include the token. Everyone who has already solved the puzzle can then verify that you did indeed solve it (or at least got somebody else to solve it on your behalf). This step is optional because Additional Logging Requirements cannot be mandatory, but if you don't include your token we will all just have to assume you cheated somehow!

I have tuned this puzzle so that it should take an average computer less than 24 hours to find the solution. There is a little trick you will have to figure out, or it could take a lot longer!

One more thing: I tested the solution and my token is: 1b7naga

Have Fun!


You can validate your puzzle solution with certitude.

Additional Hints (Decrypt)

[puzzle:] unfupng [hide:] uvtu

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)