Data security is the practice of protecting digital data from unauthorized access and unwanted actions such as cyberattack or data breach. Various technologies are used for ensuring data security. These include disk encryption, software-based security, hardware-based security, data masking, backups and data erasure. Securing communication in the presence of third parties is under the domain of cryptography. Diverse aspects of data confidentiality, integrity, non-repudiation and authentication are fundamental considerations of cryptography. The areas of study in cryptography include symmetric-key cryptography, public-key cryptography, cryptanalysis, cryptosystems, etc. This domain is crucial in the areas of electronic commerce, digital currencies, military communications and chip-based payment cards. This book contains some path-breaking studies in the field of data security and cryptography. It elucidates the concepts and innovative models around prospective developments with respect to these fields. It is a complete source of knowledge on the present status of these important fields.