Code of the Week!

view of the enigma machine

For your chance to win your very own signed copy of Simon Singh's Code Book try out your codebreaking skills with the "Code of the Week".

Solution for the "Code of the Week!" week starting 24th December 2007

Week 6 - "Name the television show"

This animated television show is about a family consisting of Homer, Marg, Bart and Lisa. It is set in the town of Springfield and is the longest screening American cartoon on television.

The Simpsons

Code of the Week 6 (week starting 24th December 2007)

Playfair Cipher

The Playfair Cipher uses a 5x5 grid containing a keyword. The keyword is written across the first cells of the square. The keyword that is used in this Playfair Cipher is ‘blue’.

B L U E A
C D F G H
I K M N O
P Q R S T
V W X Y Z

To decipher the Playfair cipher, you must consider where the pair of letters are in the grid. The letter pair will fall into one of three categories – both letters are in the same row, or both letters are in the same column, or the letters share neither a row nor a column.

‘GOLDEN RULES’  

  1. If both letters are in the same row, then they are replaced by the letters to the immediate left of each one. 'rs' becomes 'QR'. If a letter is at the beginning of a row, it is replaced by the letter at the end; 'pr' becomes 'TQ'.

  2. If both letters are in the same column, then they are replaced by the letter immediately above each one; 'mx' becomes 'FR'. If a letter is at the top of a column, it is replaced by the letter at the bottom; 'es' becomes 'YN'.

  3. If the letters are neither in the same row nor the same column, the rule differs. To decipher the first letter, look along its row until you reach the column containing the second letter; the letter at this intersection replaces the first letter. To decipher the second letter, look along its row until you reach the column containing the first letter; the letter at the intersection replaces the second letter. Hence, 'rw' becomes 'QX'.

Use these ‘Golden Rules’ and the 5x5 grid above to help you decipher this week’s ciphertext.

For more information on the Playfair cipher see http://www.bryson.ltd.uk/cgi-bin/playfair

Good luck!

‘Name the television show’

Ciphertext

Zonp eoknhzlg sauabppnio tgkz np blmaz h hunkew hisynpposn mh Otnux, Rutc, Eutz hkg Bkte. Op np ygp oo sga ztyk mh Tqpmsncmauh lkg np zoa uiongtp pgsueokoh Enupmhbi gutztio io sauabppnio.