This new edition introduces the basic concepts in computer networks, blockchain, and the latest trends and technologies in cryptography and network security. The book is a definitive guide to the principles and techniques of cryptography and network security, and introduces basic concepts in computer networks such as classical cipher schemes, public key cryptography, authentication schemes, pretty good privacy, and Internet security. It features a new chapter on Artificial Intelligence security and the latest material on emerging technologies, related to IoT, cloud computing, SCADA, blockchain, smart grid, Big Data analytics, and more. Primarily intended as a textbook for courses in computer science, electronics and communication, the book also serves as a basic reference and refresher for professionals in these areas.