Geocache placed with permission from George Mason University. Please only search for geocache during daylight hours.
Welcome back to the "Cryptocache Challenge!" This challenge will put your cryptological, mathematical, and geocaching skills to the test. This challenge contains a series of eight geocaches hidden at different locations around Fairfax. Each geocache contains an encrypted message in its description. Each geocache also uses a different cryptosystem. It is recommended to find the first geocache of this series and go in order and find the seventh geocache second to last because the difficulty of decrypting the messages increase. The eighth geocache will be found last because the first seven are required to be found first because they contain information that will be used to find the eighth geocache. Are you up to the challenge? If so, good luck!
For this geocache, you will need to use the Hill Cipher to decrypt the message below. The keyword is "HILL", with a = 7, b = 8, c = 11, d = 11. But don't forget to find the inverse of the matrix and use mod26.
HAVXIKAYTARBQRZXTFOCUNREYKDIQHQIOPCFCIXPVLTFOCUNLZTFZXTFZHXD
Once you've decrypted the message, you should get numbers. Use the diagram below and put the correct numbers in each box.
N ▢▢º ▢▢.▢▢▢’
W ▢▢º ▢▢.▢▢▢’
If you need a little help, here's a link.
http://practicalcryptography.com/ciphers/hill-cipher/
There's also something called a "special character" in the logbook located on the first page. A special character is either a letter or a number and they will be used to decrypt the eighth geocache's message. So don't forget to take a picture of that to remember!
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