Discussion Groups are back for this term, starting with a talk about cryptography by Sir Alexander Thomas Aubrey Oakes, University Number 0624729.

Cryptography can be thought of as the science of keeping secrets. While you may not have any skeletons in the closet, you probably have credit cards, e-mail accounts, personal details and less than 5 passwords that you can remember. To protect these your computer uses algorithms that are publicly known and easily looked up by anyone. If people know exactly how your private information is hidden, how come no one knows that your password is a play on "Manchester City" and that you live in Chelsea?

It's surprising what information can be given away without fully compromising what's important. It is even possible to hold a conversation in the presence of a 3rd party who knows everything you do, and communicate without the 3rd party being able to understand what is being said. This in essence is public key cryptography.

After which, we secretly move on to the pub.