This book assumes a minimal background in programming and a level of math sophistication equivalent to a course in linear algebra. It provides a flexible organization, as each chapter is modular and can be covered in any order. Using Mathematica, Maple, and MATLAB, computer examples included in an Appendix explain how to do computation and demonstrate important concepts. A full chapter on error correcting codes introduces the basic elements of coding theory. Other topics covered: Classical cryptosystems, basic number theory, the data encryption standard, AES: Rijndael, the RSA algorithm, discrete logarithms, digital signatures, e-commerce and digital cash, secret sharing schemes, games, zero knowledge techniques, key establishment protocols, information theory, elliptic curves, error correcting codes, quantum cryptography. For professionals in cryptography and network security.