This book constitutes the refereed proceedings of the International Workshop on Security Protocols held in Cambridge, UK, in April 1996, in the context of the special program on computer security, cryptology, and coding theory at the Isaac Newton Institute. The 17 revised full papers and one abstract included in the book were carefully selected. Among the topics addressed are several types of public key cryptosystems, digital cash, electronic commerce, digital signatures, and visual cryptography. Besides original theoretical results, the collection of papers show a strong applications-oriented component.