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Security Engineering - The Book
Source: Ross Anderson - Posted by Eric Lubow
In this section of the book, I cover the basics of security engineering technology. The first chapter sets out to define the subject matter by giving an overview of the secure distributed systems found in four environments: a bank, an air force base, a hospital, and the home. The second chapter is on security protocols, which lie at the heart of the subject: they specify how the players in a system—whether people, computers, or other electronic devices—communicate with each other. The third, on passwords and similar mechanisms, looks in more detail at a particularly simple kind of security protocol that is widely used to authenticate people to computers, and provides the foundation on which many secure systems are built.
The next two chapters are on access control and cryptography. Even once a client (be it a phone, a PC, or whatever) has authenticated itself satisfactorily to a server—whether with a password or a more elaborate protocol—we still need mechanisms to control which data it can read or write on the server, and which transactions it can execute. It is simplest to examine these issues first in the context of a single centralized system (access control) before we consider how they can be implemented in a more distributed manner using multiple servers, perhaps in different domains, for which the key enabling technology is cryptography. Cryptography is the art (and science) of codes and ciphers. It is much more than a technical means for keeping messages secret from an eavesdropper. Nowadays it is largely concerned with authenticity and management issues: “taking trust from where it exists to where it’s needed” [535].
The final chapter in this part is on distributed systems. Researchers in this field are interested in topics such as concurrency control, fault tolerance, and naming. These take on subtle new meanings when systems must be made resilient against malice as well as against accidental failure. Using old data—replaying old transactions or reusing the credentials of a user who has left some time ago—is a serious problem, as is the multitude of names by which people are known to different systems (email addresses, credit card numbers, subscriber numbers, etc.). Many system failures are due to a lack of appreciation of these issues.
