Providing security for multimedia data has become an important issue for individuals, companies and governments. Traditional cryptographic methods for multimedia security tend to add a significant amount of overhead to achieve quality encryption levels. This additional overhead is not conducive to processing large amounts of data in real-time applications. Recursive sequence based multimedia encryption theory can meet the stringent performance requirements for real-time multimedia applications, while achieving different levels of security. This book focuses on presenting efficient encryption approaches that are suitable for real-time applications. It is intended to be used by individuals interested in privacy, copyright protection, and security of digital information. Features: (1) Present a straightforward multimedia encryption system that can encrypt different types of multimedia data using different key-dependant recursive sequences. (2) Present multimedia encryption techniques using general 2D or 3D recursive sequence transforms. (3) Analyze and compare security issues of several multimedia encryption methods based on recursive sequences.