Cryptography is the essential and efficient ingredient to the recipe of security solutions. With the arrival of new age communication systems and high speed networks in the future cryptography will have a key role to play. This book talks about the crucial security challenges that the computing world is facing today and also discusses several techniques to fight against such attacks. The chapters in this book discuss various facets of cryptography and their applications. It will cater to the needs of researchers engineers graduates and PhD students working in this field. It will also be beneficial to teachers at universities and colleges as a reference.