Hardly a month passes without a news splash on cyber security—be it a new virus strain, botnets, denial of service, or a high-profile break-in. Security was once the preserve of the military and, more recently, of banks. Today, awareness of security policy and practices has moved to the homes and offices of people at large. We are more dependent on the Internet than ever before—for banking, e-trading, e-commerce, and more. All of a sudden it seems like identity theft, phishing attacks, and spyware are everyone's concerns. Indeed, given the stakes involved, it is hardly surprising that many corporations worldwide have increased their spending on IT security over the last ten years. Risk analysis, security policy and management, compliance, etc., all come under the purview of security. This book, Cryptography, Network Security, and Cyber Laws, is principally about providing and understanding technological solutions to security. It is about the underlying vulnerabilities in systems, services, and communication protocols. It is about their exploitation and methods to defend against them.