Security is the science and technology of secure communications and resource protection from security violation such as unauthorized access and modification. Putting proper security in place gives us many advantages. It lets us exchange confidential information and keep it confidential. We can be sure that a piece of information received has not been changed. Nobody can deny sending or receiving a piece of information. We can control which piece of information can be accessed, and by whom. We can know when a piece of information was accessed, and by whom. Networks and databases are guarded against unauthorized access. We have seen the rapid development of the Internet and also increasing security requirements in information networks, databases, systems, and other information resources. This comprehensive book responds to increasing security needs in the marketplace, and covers networking security and standards. There are three types of readers who are interested in security: non-technical readers, general technical readers who do not implement security, and technical readers who actually implement security. This book serves all three by providing a comprehensive explanation of fundamental issues of networking security, concept and principle of security standards, and a description of some emerging security technologies. The approach is to answer the following questions: 1. What are common security problems and how can we address them? 2. What are the algorithms, standards, and technologies that can solve common security problems? 3.