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 26th November 2007

Week 2 – ‘A Gruesome Fate’

Substitution Cipher

Plaintext 

a 

b 

c 

d 

e 

f 

g 

h 

i 

j 

k 

l 

m 

n 

o 

p 

q 

r 

s 

t 

u 

v 

w 

x 

y 

z 

Ciphertext 

h 

t 

l 

k 

s 

o 

b 

a 

m 

w 

d 

f 

i 

n 

g 

e 

p 

j 

v 

u 

q 

r 

x 

c 

y 

z 

Plaintext 

Mary Queen of Scots used a cipher system to encrypt the messages that she sent to her supporters. Tragically the message that incriminated her was intercepted by Francis Walsingham, the head of Elizabeth's secret service, whose team had little trouble deciphering it and discovering the details they needed to stop the entire plot. As a result, Mary Queen of Scots was led from her room to be executed at the order of Queen Elizabeth I. 

‘A Gruesome Fate’

Ciphertext: 

Ihjy Pqssn go Vlguv qvsk h lmeasj vyvusi ug snljyeu uas isvvhbsv uahu vas vsnu ug asj vqeegjusjv. Ujhbmlhffy uas isvvhbs uahu mnljmimnhusk asj xhv mnusjlseusk ty Ojhnlmv Xhfvmnbahi, uas ashk go Sfmzhtsua'v vsljsu vsjrmls, xagvs ushi ahk fmuufs ujgqtfs kslmeasjmnb mu hnk kmvlgrsjmnb uas ksuhmfv uasy nssksk ug vuge uas snumjs efgu. Hv h jsvqfu, Ihjy Pqssn go Vlguv xhv fsk ojgi asj jggi ug ts scslqusk hu uas gjksj go Pqssn Sfmzhtsua M.

Code of the Week 2 (week starting 26th November 2007)

Substitution Cipher

A Substitution cipher is one where each letter of the alphabet is substituted with another letter or symbol. For example, in a piece of text the word AND may be replaced by the word HJP, where H represents A, and J represents N, and P represents D.

Substitution ciphers can be broken using a method known as frequency analysis. This method involves finding the letter that appears most frequently in the ciphertext and replacing it with the most frequently used letter in English which happens to be E, T, then A.

See http://www.simonsingh.net/The_Black_Chamber/substitution.html in the Black Chamber to find out more about substitution ciphers. You can also find out how to crack the substitution cipher at http://www.simonsingh.net/The_Black_Chamber/crackingsubstitution.html

Good luck!

"A Gruesome Fate"

Ciphertext: 

Ihjy Pqssn go Vlguv qvsk h lmeasj vyvusi ug snljyeu uas isvvhbsv uahu vas vsnu ug asj vqeegjusjv. Ujhbmlhffy uas isvvhbs uahu mnljmimnhusk asj xhv mnusjlseusk ty Ojhnlmv Xhfvmnbahi, uas ashk go Sfmzhtsua'v vsljsu vsjrmls, xagvs ushi ahk fmuufs ujgqtfs kslmeasjmnb mu hnk kmvlgrsjmnb uas ksuhmfv uasy nssksk ug vuge uas snumjs efgu. Hv h jsvqfu, Ihjy Pqssn go Vlguv xhv fsk ojgi asj jggi ug ts scslqusk hu uas gjksj go Pqssn Sfmzhtsua M.