Based on the simpler Vigenere cipher, this uses an alternate tableau. The "Alphabet Key" helps decide the alphabet to use to encrypt and decrypt the message. The "Passphrase" is the code word used to select columns in the tableau. Instead of just using the alphabet from A to Z in order, the alphabet key puts a series of letters first, making the cipher even tougher to break. This style of encryption is also called a Quagmire III.

This tool was built to play with the Kryptos codes – a set of letters that are cut out of a sheet of copper at the CIA headquarters. To help you out with the codes, you can pre-populate the form with the K1 or K2 sections. Also, there is a Corrected K2 that shows where a letter was omitted (the lower-case "s" near the end).

This is your encoded or decoded text: