Codes and the Quantum Computer

Summary

Students presentations

1st videoconference: 19 May 2005, 10.30am start (UK time)
2nd videoconference: 5 July 2005, 10.30am (UK time)

Preliminary task and follow-up project work

This conference consists of two videoconferences with follow-up project work set in between - see http://www.motivate.maths.org/teachers/2_conference_format.htm for more details.

We all rely on codes to keep our credit card details secret when we buy something online. How secure are these codes? How do codebreakers go about trying to crack a code?

This conference will look at methods of breaking codes from frequency analysis to the use of prime numbers.There will also be a brief introduction to the concept of quantum computers, which have the potential to revolutionise codes and codebreaking all over again.

Further reading:
The Code Book: The Secret History of Codes and Code-breaking by Simon Singh, published by Fourth Estate, London, ISBN 1-85702-889-9
Simon Singh's website
You can download Simon Singh's Code Book on CD-Rom here.

Schools already booked for this conference

Article on the Plus website which covers part of the material Artur Ekert will talk about during this conference.
Second part to follow soon.

You may also find Claire Ellis' article in the same edition of Plus interesting. This is about the Enigma machine, which the Germans used to encode their secret messages in the Second World War. Codebreakers at Bletchley Park in the UK were able to crack these messages thus shortening the war, possibly by as much as two years.

Preliminary task to be done before the first videoconference

Artur Ekert's powerpoint slides from the first videoconference

Student presentations given during the second videoconference.

Project work

• History of cryptography. How did Julius Caesar encode messages to his generals, and Mary Queen of Scots plot treason against Elizabeth I? Why are these codes not very secure? In this project, you can explore the history of codes and codebreaking, and try your hand at decrypting the messages given. You can also try to make an unbreakable code for other schools participating in this conference to break!
• Unbreakable codes. Find out how to use a binary one-time page to make a truly unbreakable code.
• Public-key ciphers. Mathematics comes to the aid of cryptographers.
• Messages to decipher. Students from the Nottingham schools and from Seven Kings High School, Essex, have sent these challenges for other schools! Can you work out what their messages say?