PORTIA: Of a strange nature is the suit you follow; Yet in such rule that the Venetian law Cannot impugn you as you do proceed. [To Antonio.] You stand within his danger, do you not?
|--The Merchant of Venice, IV, i, 177–180.|
A security policy defines “secure” for a system or a set of systems. Security policies can be informal or highly mathematical in nature. After defining a security policy precisely, we expand on the nature of “trust” and its relationship to security policies. We also discuss different types of policy models.
Consider a computer system to be a finite-state automaton with a set of transition functions that change state. Then:
Definition 4–1. A security policy is a statement that partitions ...