Users and Uses of This Book

This book is intended for the study of computer security. Many of you want to study this topic: college and university students, computing professionals, managers, and users of all kinds of computer-based systems. All want to know the same thing: how to control the risk of computer security. But you may differ in how much information you need about particular topics: Some want a broad survey, whereas others want to focus on particular topics, such as networks or program development.

This book should provide the breadth and depth that most readers want. The book is organized by general area of computing, so that readers with particular interests can find information easily. The chapters of this book progress in an orderly manner, from general security concerns to the particular needs of specialized applications, and finally to overarching management and legal issues. Thus, the book covers five key areas of interest:

• Introduction : threats, vulnerabilities, and controls

• Encryption : the "Swiss army knife " of security controls

• Code : security in programs, including applications, operating systems, database management systems, and networks

• Management : implementing and maintaining a computing style

• Law, privacy, ethics : nontechnical approaches by which society controls computer security risks

These areas are not equal in size ; for example, more than half the book is devoted to code because so much of the risk is at least partly caused by program code that executes on computers.

The first chapter introduces the concepts and basic vocabulary of computer security. The second chapter provides an understanding of what encryption is and how it can be used or misused. Just as a driver's manual does not address how to design or build a car, Chapter 2 is for users of encryption, not designers of new encryption schemes. Chapters 3 through 7 cover successively larger pieces of software: individual programs, operating systems, complex applications like database management systems, and finally networks, which are distributed complex systems. Chapter 8 discusses managing and administering security, and finding an acceptable balance between threats and controls. Chapter 9 covers the way society at large addresses computer security, through its laws and ethical systems and through its concern for privacy. Finally, Chapter 10 returns to cryptography, this time to look at the details of the encryption algorithms themselves .

Within that organization, you can move about, picking and choosing topics of particular interest. Everyone should read Chapter 1 to build a vocabulary and a foundation. It is wise to read Chapter 2 because cryptography appears in so many different control techniques. Although there is a general progression from small programs to large and complex networks, you can in fact read Chapters 3 through 7 out of sequence or pick topics of greatest interest. Chapters 8 and 9 may be just right for the professional looking for nontechnical controls to complement the technical ones of the earlier chapters. These chapters may also be important for the computer science student who wants to look beyond a narrow view of bytes and protocols. Chapter 10 is for people who want to understand some of the underlying mathematics and logic of cryptography.

What background should you have to appreciate this book? The only assumption is an understanding of programming and computer systems. Someone who is an advanced undergraduate or graduate student in computer science certainly has that background, as does a professional designer or developer of computer systems. A user who wants to understand more about how programs work can learn from this book, too; we provide the necessary background on concepts of operating systems or networks, for example, before we address the related security concerns.

This book can be used as a textbook in a one- or two-semester course in computer security. The book functions equally well as a reference for a computer professional or as a supplement to an intensive training course. And the index and extensive bibliography make it useful as a handbook to explain significant topics and point to key articles in the literature. The book has been used in classes throughout the world; instructors often design one-semester courses that focus on topics of particular interest to students or that relate well to the rest of a curriculum.