Computers need not just automate what is already being done, but can do completely new things. In the 1970s a new form of cryptography was invented, which is usually presented as an esoteric application of number theory. This new cryptography is asymmetric, meaning that the coding and decoding methods are different. In fact, the basic ideas are easily explained using geometric arguments, and the amazing new applications of asymmetric methods - such as digital cash - become easy to understand.

Harold Thimbleby is professor of computer science at Swansea University where he established the Future Interaction Technology Lab. His passion is designing dependable computer systems to accommodate human error. He has been a Royal Society Wolfson Research Merit award holder and a Royal Society Leverhulme Trust Senior Research Fellow. He has also contributed to the Encyclopedia Brittanica and was Gresham Professor of Geometry between 2001 and 2004.
All of Professor Thimbleby's previous lectures may be accessed here.