Pretty Good Privacy

Brian Rotman

• The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography by Simon Singh
  Fourth Estate, 402 pp, £16.99, September 1999, ISBN 0 85702 879 0
• In Code: A Mathematical Journey by Sarah Flannery
  Profile, 292 pp, £14.99, April 2000, ISBN 1 86197 222 9
• Privacy on the Line: The Politics of Wiretapping and Encryption by Whitfield Diffie and Susan Landau
  MIT, 346 pp, £10.50, April 1999, ISBN 0 262 54100 9

The English mathematician G.H. Hardy, who worked in the purest of all mathematical fields, the theory of numbers, used to boast in his patrician way that nothing he did in mathematics would ever be useful. He must be turning in his grave at developments in the ‘science of secrecy’ over the last quarter of a century. Like so many other practices, it has been transformed into a species of applied mathematics by the digital computer, with Hardy’s beloved prime numbers playing a leading role. How this came about is the subject of Simon Singh’s The Code Book, a very readable and skilfully told history of cryptography. Singh’s method is to attach the abstract ideas involved to someone who thought of them, failed to think of them, championed them, or suffered their consequences – this last allowing him to include Mary Queen of Scots, whose unfortunate contribution to the art of secrecy was to correspond with her conspirators using an insecure cipher.