"This book summarizes the key areas of cyber security. The book focuses on the specific paradigm of blockchain technology to enforce cyber security. The book demonstrates the deployment of various security attacks in the real-time network environment. The challenges related to cyber security and the solutions based on Software Defined Networks are discussed in detail in the book. The book uniquely presents the solutions to cyber security attacks by considering various real-time applications based on the Internet of Things, Wireless Sensor Networks, Cyber-Physical Systems, and Smart Grids. The book is helpful for academicians and research scholars worldwide working in the cyber security field. The book is also beneficial to industry experts working in the cybersecurity field. The undergraduate students who are exploring the area of cyber security can also utilize the contents of the book. The book can help design an advanced-level course on cyber security for undergraduate and postgraduate students. It is also helpful for industry penetration testers and vulnerability assessment experts. The book emphasizes the following significant aspects in the field of cyber security in total depth: Application Layer Attacks and Detections, Security & Privacy Issues in Cloud Computing, Zero-Day Attack Detection, Security Analysis in Smart Environment, Security and Privacy Issues in Searchable Encryption in Cloud, Provable Security, Security of IoT platforms, Volatile Memory Forensics, Formal methods and verification for security, Security Aspects of Blockchain Technology, Challenges in Cyber Security-based Internet of Things, Realizing the Cloud-based Blockchain Platform, SDN enabled Blockchain network"--