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Urban Cipher Mystery Cache

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GhillieFeet83: Quitting geocaching...no longer into it

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Hidden : 3/30/2012
Difficulty:
3 out of 5
Terrain:
3.5 out of 5

Size: Size:   small (small)

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Geocache Description:



CONGRATULATIONS GOES TO AutonomousAnonymous FOR THEIR VERY FIRST FTF!! WHOOHOO!!

THE CACHE IS NOT AT THE ABOVE COORDINATES. PLEASE READ THE INSTRUCTIONS BELOW TO SOLVE THE PUZZLE!


I decided to change this up a bit and make it easier for people. I wasn't getting very many bites on this particular puzzle. My only wish is that you work the cipher with pencil and paper before you seek answers somewhere else.


The cipher that you're about to work on is called a Bifid Cipher. The Bifid Cipher uses a Polybius Square to encipher a message in a way that makes it fairly difficult to decipher without knowing the secret. This is because each letter in the ciphertext message is dependent upon two letters from the plaintext message. As a result, frequency analysis of letters becomes much more difficult. However, I have done this cipher as simple as possible, no keywords....maybe save that for later puzzle ;)

So here are the instructions on how to encipher and decipher text:


Bifid Cipher

Bifid Cipher
The first step is to use the Polybius Square to convert the letters into numbers. We will be writing the numbers vertically below the message:
secret message

411414 3144121

353254 2533125


The numbers are now read off horizontally and grouped into pairs:

41 14 14 31 44 12 13 53 25 42 53 31 25

The Polybius Square is used again to convert the numbers back into letters which gives us our ciphertext: qddltbcxkrxlk

To decipher a Bifid encrypted message, you first convert each letter into its corresponding number via the Polybius Square. Now, divide the long string of numbers into two equal rows. The digit in the top row and the digit in the bottom row will together reference the decoded letter in the Polybius Square.

So here are the coordinates that you need to DECIPHER:

  • N 39 riugvvshtrqdoiqqzwquimz
  • W 105 vsbgtkrqbkewurooomzde

Additional Hints (Decrypt)

Ybbxf yvxr gur bguref...bayl abg

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)