Revised and updated, this new edition expands algebraic coverage with an additional chapter on groups and details about rings in the finite fields. The comprehensive text includes cryptography, number theory, and two completely new chapters on error correcting codes. It presents various types of algorithms with their complexities. A thorough explanation of the Rijndael Algorithm helps students understand the recently adopted data encryption standard. Unlike other texts, the authors discuss how mathematical techniques can be used to solve practical problems. CRC codes, clearer proof presentation, and twice the number of exercises are added through an interactive CD.