The Case of the Uncrackable Code

From the Caesar Cipher to the Da Vinci Code, people have been fascinated by secret messages. The mathematics of codes lets us to do everything from photographing the surface of Mars to shopping securely on eBay. Find out how prime numbers are now the key to codes which protect credit cards from internet hackers, and how, in the digital age, i-pods and digital TV are just a load of 0s and 1s.