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 10th December 2007

Week 4 "Who am I?"

Playfair Cipher 

From an early age he wanted to be a football player and by the young age of twenty eight he had become one of the most well known names around the world wearing the coveted Number seven shirt in the most successful United squad ever.

Who am I?

Ciphertext: 

IS PN CL AB SQ VD KB KC VB UO AE SR CA FL CO RS CB NV MS VF ZD SD QC DW OK DZ TN MH BF CT KS ZB UO ZD KH KO KC FC EC AD PN CT UC SH OK BU RP PZ AU VN HU PX XO LC UB AF TR LQ ER KC XP SQ BY AB DQ MH OK AD SX KE AE QL WG DT TA ZA LO IK TS HQ OK BU RP SP NE OH AT VO KL ML QH EK AR UL BE AZ DT 

Code of the Week 4 (week starting 10th 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 "SPORT".  

S 

P 

O 

R 

T 

A 

B 

C 

D 

E 

F 

G 

H 

I 

K 

L 

M 

N 

Q 

U 

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. 'GI' becomes 'FH'. If a letter is at the beginning of a row, it is replaced by the letter at the end; 'LQ' becomes 'UN'.

  2. If both letters are in the same column, then they are replaced by the letter immediately above each one; 'HX' becomes 'CN'. If a letter is at the top of a column, it is replaced by the letter at the bottom; 'PM' becomes 'WG'.

  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, 'VI' becomes 'YF'.

You can use this set of ‘Golden Rules’ to decipher the ‘Code of the Week’ 

For more information on the Playfair Cipher see (http://en.wikipedia.org/wiki/Playfair_cipher)

Good luck!

"Who am I?"

Ciphertext: 

IS PN CL AB SQ VD KB KC VB UO AE SR CA FL CO RS CB NV MS VF ZD SD QC DW OK DZ TN MH BF CT KS ZB UO ZD KH KO KC FC EC AD PN CT UC SH OK BU RP PZ AU VN HU PX XO LC UB AF TR LQ ER KC XP SQ BY AB DQ MH OK AD SX KE AE QL WG DT TA ZA LO IK TS HQ OK BU RP SP NE OH AT VO KL ML QH EK AR UL BE AZ DT