Is there a way to easily encode a message without a computer on either end? I enjoy making notes and passing them to my friends, and I also like making them encrypted for no reason. My friends enjoy it too, but it's a bit annoying to use the Caesar cipher for everything because its repetitive and takes forever. Is there a better pen-and-paper way of encrypting messages?
Most of the classical crypto algorithms used in the pre computer era can be doable with pen and paper!! Lot of there are in the list see here http://practicalcryptography.com/ciphers/classical-era/ . Try Vigenere and change you keys frequently.