Many engineers consider cryptography to be a sort of magic security dust that they can sprinkle over their hardware or software, and which will imbue those products with the mythical property of "security." Security is only as strong as the weakest link, and the mathematics of cryptography is almost never the weakest link. The fundamentals of cryptography are important, but far more important are, how those fundamentals are implemented and used. You can argue whether the stake should be a mile or a mile-and-a-half high, but the attacker is simply going to walk around the stake. Security is a broad stockade: it's the things around the cryptography that make the cryptography effective. This book is intended for use in Graduate and Post Graduate courses, and for the professional cryptographers, presenting the techniques and algorithms of the greatest interest to the current practitioner, along with the supporting motivation and background material.