This book offers a comprehensive, yet relentlessly practical overview of the fundamentals of modern cryptography. Welschenbach avoids complexities by explaining cryptography and its mathematical basis in terms a programmer can easily understand. Coverage mainly focuses on the practical aspects involved in implementing public key cryptography methods, such as the RSA algorithm. It also gives both a technical overview and an implementation of the Rijndael Advanced Encryption Standard algorithm.The book includes a wide-ranging library of code in C and C++, including the RSA algorithm, completed by an extensive Test Suite that proves that the code works correctly. Readers will learn, step by step, how to implement a platform independent library for the all-important multi-precision arithmetic used in modern cryptography. This is followed by an implementation of the cryptographic algorithms themselves. The CD-ROM includes all the programs presented in the book, x86 assembler programs for basic arithmetical operations, implementations of Rijndael in both C and C++ and more.