Computer Security: Art and Science

Chapter 15. Access Control Mechanisms

	CASSIO: Why, no. The day had brokeBefore we parted. I ha' made bold, Iago,To send in to your wife. My suit to herIs that she will to virtuous DesdemonaProcure me some accéss.
	--The Tragedy of Othello, III, i, 32–36.

Recall the access control matrix discussed in Chapter 2. As in the theoretical model, an implementation of the array and the commands to manipulate it provide a mechanism that the system can use to control access to objects. Unfortunately, there are several problems with a straightforward implementation. On a typical system, the number of subjects and objects will be sufficiently large that the matrix's size will use significant amounts of storage. Second, most entries in the matrix will be either ...