Other Site Lists
http://endgame-arg.wikia.com/wiki/Useful_Tools - tools collected by Endgame ARG players
http://argonauts.wikia.com/wiki/For_Players - tools collected by ARGonauts wiki
http://wiki.gamedetectives.net/index.php?title=ARG_Toolbox - Toolbox collected by Game Detectives
Vigenere : A special cipher somewhat based on the Caesarian shift, but you change the value of N with each letter and it is all based on a passphrase. A pretty strong cipher for beginners, and one that can be done on paper easily.
Keyed Vigenere : This modified cipher uses an alphabet that is out of order. Two keys are used. One creates the alphabet, the second is the encoding passphrase. This was created to help decrypt the Kryptos sculpture.
Vigenere Autokey : Instead of repeating the password used in order to encrypt text, this uses the password once and then the plaintext. It is harder to break than if you were to just use the password to encrypt your message.
Video tutorial: https://youtu.be/LnBY3YVg5Qg
In mushroom we use mostly Vigenere Autokey. Previous keys and passwords here.
A site with the math behind many ciphers - https://www.programming-algorithms.net/