When the first edition of this book was published in 1989, viruses were uncommon, the Internet was only used by serious professionals, and computer crime was a rarity. This revision has updated coverage of viruses, worms, Trojan horses, firewalls, private e-mail, and new encryption technologies. The chapters of the book progress in an orderly manner. After an introduction, the topic of encryption is presented as the first tool in computing security. The book continues through the different kinds of computing applications, their weaknesses, and their controls. The applications area include: general programs, operation systems, database management systems, remote access computing, and multi-computer networks. These sections begin with a definition of the topic, continue with a description of the relationship of security to the topic, and conclude with a statement of the current state-of-the-art of computer security research related to the topic. The book concludes with an examination of risk analysis and planning for computer security, and a study of the relationship of law and ethics to computer security.