When I have experimented with using a key higher than 26 on a Caesar cipher, I have had some very ...interesting... results. The encryption works fine, but when I attempt to decrypt the encrypted message, I am unable to decrypt the message successful.
I understand that a Caesar can theoretically have a key size of 26, I am just curious as to what would happen with a longer key. Can somebody assist with both the mathematical side, and if it is possible to use the cipher with a key size higher than 26?
EDIT: In my program I am converting the message to ASCII, adding the key size. To decrypt, I convert it back from ASCII to characters.