Grid Ciphers

Playfair Cipher

Playfair Cipher Notes How to use the Playfair Cipher in the manner employed by the National Cipher Challenge in 2004 for challenge 5b.

Digraph counter. A more complex tool which will analyse frequencies for double letter pairs. Use this tool on ciphers that you suspect are based on the Playfair system.


Playfair Cipher Wikipedia entry on Playfair Cipher systems.

Single Playfair Cipher Nova TV Nazi Secrets Program webpage on the Single Playfair Cipher. This is the system used for Cipher Challenge 2004 5B.

playfair.xls This XL worksheet will decipher the Cipher Challenge 2004 5b Playfair cipher, provided that you know the right keyword.

Double Playfair Cipher Nova TV Nazi Secrets Program webpage on the Double Playfair Cipher. This is exactly the system used for Cipher Challenge 2004 7B.

double playfair.xls This XL worksheet will decipher the Cipher Challenge 2004 7b double Playfair cipher, provided that you know the right keywords and how to arrange them in the grid.

last updated 10th June 2011