AutoKey Cipher

  1. Key in a word or a short phrase in the top box
  2. Enter a KEY LETTER
  3. Press Encipher or Decipher
  4. The results appear in the bottom box

To “Break” a secret message that was enciphered with
an AutoKey Cipher, place the message in the top space, enter a Key Letter
and click Decipher. If the message does not appear, change the Key Letter
and Decipher again, trying all Key Letters in turn until one Key Letter reveals
the secret message.

Try this secret message – DUPO KOBXQAU SQNSHB TW EEAG HJ FANWC

(Your Browser must be JavaScript Enabled for this Cipher to work!)



Key Letter


(A JavaScript program written by Jim Hannon for Secret Code Breaker)