This book provides state-of-the-art coverage of the principles, techniques, and management of issues in cyber security, including threat attacks, privacy, signature and encryption schemes. One of the most important topics addressed concerns lightweight solutions for public key encryption in resource-constrained environments; the book highlights the latest developments in this area. Authentication is another central issue in cyber security. In this book, we address this aspect and sub-aspects ranging from cryptographic approaches to practical design issues, such as CAPTCHA. Privacy is another main topic that is discussed in detail, from techniques for enhancing privacy to pseudonymous schemes. Addressing key issues in the emerging field of cyber security, this book effectively bridges the gap between computer security and threat attacks, and showcases promising applications involving cryptography and security.