The discipline of cryptography studies the techniques and practices which can be used for secure communication in the presence of hostile parties. Its primary objective is to construct and analyze protocols which can be used to stop unauthorized parties from reading private messages. Cryptography is a multidisciplinary field which draws on the principles of computer science, mathematics, electrical engineering, physics and communication science. The guiding principles of this subject are data integrity, data confidentiality, non-repudiation and authentication. Modern cryptography can be categorized into various sub fields such as symmetric key cryptography, public key cryptography, cryptanalysis and cryptosystems. It finds application across various domains such as electronic commerce, digital currencies, computer passwords, military communications and payment systems. This book presents the complex subject of cryptography in the most comprehensible and easy to understand language. The topics included herein on cryptography are of utmost significance and bound to provide incredible insights to readers. This book is an essential guide for both academicians and those who wish to pursue this discipline further.