Substitution Cipher
Substitution Cipher printable sheet
In any language some letters tend to appear more often than others.
Which letters do you think are the most common in English?
Is the frequency of letters in the following sentence representative?
The quick brown fox jumps over the lazy dog.
In the coded text below, every letter in the original message was switched with another letter. Find out which are the most (and least) common letters used in English to help you crack this coded message:
If you want to work on a computer to solve the problem, you can download the message as a text file which doesn't contain any line breaks.
If you are interested in code breaking you might enjoy the Secondary Cipher Challenge.
You can read about Substitution Ciphers and Frequency Analysis on Simon Singh's website: http://www.simonsingh.net/The_Black_Chamber/crackingsubstitution.html
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