Keyword Cipher

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

The Keyword Cipher uses a Keyword to rearrange the letters in the alphabet. These different letters are then substituted for the letters in the message to create a secret message. That Keyword is needed to decipher the secret message. The Secret Code Breaker “Handbooks” have computer programs that can be used to determine Keywords and decipher secret messages.

Decipher this secret message – Use SECRET as the Keyword
QDFP FP S HTYWLOR CFMDTO PTCOTQ JTPPSBT

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

Message:

Key Word

Result:

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

Downloadable Keyword Cipher Software

A program written by Peter Conrad that can break many secret messages that have been enciphered using a Keyword Cipher. It is a different program than the Keyword Cipher program that comes on the diskette included with “Secret Code Breaker – A Cryptanalyst’s Handbook”

Click Here to Download

The download is a Zip file. Requires IBM compatible computer, running DOS or Windows.
Currently no Macintosh version is available (will run using RealPC).