Communications represent a strategic sector for privacy protection and for personal, company, national and international security. The interception, damage or lost of information during communication can generate material and non material economic damages from both a personal and collective point of view. Giving the reader information relating to all aspects of communications security, this book begins at the base ideas and builds to reach the most advanced and updated concepts. The comprehensive coverage makes the book a one-stop reference for integrated system designers, telecommunication designers, system engineers, system analysts, security managers, technicians, intelligence personnel, security personnel, police, army, private investigators, scientists, graduate and postgraduate students and anyone that needs to communicate in a secure way.