Le Chiffre: The Cipher

Every Bond movie has a villain, and one of the more ruthless is financier Le Chiffre in Casino Royale. Le Chiffre, French for "The number", isn't his real name of course but his adopted name. It suits because he is a mathematical genius. That's why he is so good a card player, it is founded, in part, on his skills at probability.

There is another translation of "Le Chiffre" though that is also rather ironic. It also means "The Cipher". If Bond is to communicate with M and his team back at base securely, he needs a secure way to do it. He needs a way that prevents Le Chiffre from intercepting and reading his messages. He needs a cipher!

What is a cipher? It's just a set of instructions to follow that will allow you to Scramble (encode) a message in a way that means someone else can later unscramble (decipher) it. The difference between a cipher and a code is that in a cipher each symbol is processed one at a time, whereas in a code whole words are substituted for new words.

Let's look at some different ciphers Bond might think about using...

This article is based on the Science Week show given by Chris Harte of the Department of Electronic Engineering, Queen Mary, University of London.