This text covers the fundamentals of cryptography, which is concerned with methods of security in the storage and transmission of information. Computers are now found in every layer of society, and information is being communicated and processed automatically on a large scale. Examples include medical and financial files, automatic banking, video-phones, pay-tv, facsimiles, tele-shopping, and global computer networks. In all these cases there is a growing need for the protection of information to safeguard economic interests, to prevent fraud and to ensure privacy. In this book, the fundamentals of secure storage and transportation of information are described. Among other things, attention is given to symmetric (DES) and asymmetric (RSA) cryptographic algorithms, which are suitable for data security, to methods for authentication, data integrity and digital signatures, key management and to network aspects. The book will be of value to advanced students and researchers involved in data protection and information processing, including electrical engineers, mathematicians, business managers, system designers, application programmers, information analysts and security officers.