Cryptography: algorithms and standards

Recent years have witnessed an increasing interest in the subject of cryptography. A typical cryptography discussion includes encryption, decryption, and attack algorithms for a number of symmetric (or single key) and asymmetric (or two-key) techniques. Performance evaluation of these techniques deals with algorithm complexity and security. The central idea of cryptography is to develop and implement an invertible transform function over the space of coded information. Classical algorithms have survived for many years, but other ideas are coming quickly forward because of the advancement in computer technology. To design and understand cryptography we need to know the fundamentals of information coding, number theory, and some simple probabilistic models, as well as fast computational algorithms for integer arithmetic. This tutorial presents various cryptography techniques in a unified way, including classical and recent algorithms. Some software implementations are given for the purpose of illustration.