Privilege vs. permission
The majority of published papers and articles on the area of information security use the terms privilege and permission interchangeably. Even Wikipedia’s entry on privilege seems to follow this practice. However, one of the foundations of dynamic trust management is the clear distinction between an entity’s privileges and its permissions.
A privilege is an authority given to an entity that approves a specific operation on a specific resource. For example, an entry in an Access Control List (ACL) specifies a privilege, not a permission. A permission, on the other hand, is a value reached when an entity’s privileges, as well as other of its attributes, are evaluated. Therefore, the fact that an entity has been granted a privilege does not necessarily mean that it is able at a given time to perform the specified operation on the specified resource.
The dynamic trust management system ÆTHER I have designed and implemented as part of my PhD provides an example of using this distinction between privilege and permission in practice.