Editing Cipher Cracking 2009 (section)

==Approach and methodology==
You have an advantage that as engineers you know more about information theory and statistics than the average policeman or code breaking expert. You will take a structured approach to writing software code to use a process of elimination to say whether particular coding schemes were used or not.

Start with the [http://en.wikipedia.org/wiki/Playfair_cipher Playfair cipher] and the [http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher Vigenère cipher] to begin with and you should find that you can easily test the above sequence of letters to prove the Vigenère cipher was definitely not used. Then you can go onto exploring [http://en.wikipedia.org/wiki/Category:Classical_ciphers other encryption schemes]

:'''Note''' from Matthew: If you include the extra line, I'm not so sure you can prove it's not the Vigenère cipher. Also, given the date of the murder, and the dates of invention of some ciphers, there are some you could reasonably rule out (e.g. I doubt it's RSA for historical and technical reasons), however you can still implement them and try them out :). If you dig into some of the historical documents on the case you may find [http://xkcd.com/538/ clues to possible decryption keys].

We would also like you to perform simple statistical tests to show if English was the most likely language or not in the original message. Also you should be able to prove if the code is the beginning letter of a sequence of words or is composed of whole words.
A list of letter frequency rankings for different languages can be found [http://www.bckelk.ukfsn.org/words/etaoin.html here].

Then if you have time and if you are excited to take this project to a higher level you can start to check out the work of the great electrical engineer Claude Shannon and apply his techniques from information theory. You can measure the information content in the message in terms of bits for starters.