Fred Piper has been a professor of Mathematics at the University of London since 1975 and has worked in security since 1979. In 1985 he formed a company, Codes & Ciphers Ltd., which offers consultancy advice in all aspects of information security. He has lectured world-wide on a wide range of topics in information security, both academically and commercially. He is currently Director of the Information Security Group at Royal Holloway, University of London. Sean Murphy is a Professor in the Information Security Group at Royal Holloway, University of London. His research interest centre on cryptology, escpecially encryption algorithms. He published some of the early papers on differential cyptoanalysis, and has written papers on a variety of cryptographic algorithms.