Security in Computing 5th Edition by Shari Lawrence Pfleeger, Charles P Pfleeger, Jonathan Margulies

Exercise 5

Suggest an efficient scheme for maintaining a per-user protection scheme. That is, the system maintains one directory per user, and that directory lists all the objects to which the user is allowed access. Your design should address the needs of a system with 1000 users, of whom no more than 20 are active at any time. Each user has an average of 200 permitted objects; there are 50,000 total objects in the system.

Step 1 of 2

Per-Subject Access Control List

The given scheme has to allow access to 1000 users with 20 active at a time that have access to 50,000 objects out of which they can only access 200 objects. This scheme can be implemented with the group protection with the per-subject directory list.

The per-subject directory structure creates a directory for a single user and it defines the access rights to the objects and the group protection scheme is implemented. The users with specific interest forms group and the groups have certain access to the object. With the group protection the group has the right to access those objects.