Definition
Access Control List
An access control list (ACL) is a column-wise decomposition of the access matrix. Each object stores a list of pairs.
For object , the ACL is:
Object-Centric
Each object is associated with a list. Changing permissions for an object is efficient: modify only that object’s ACL.
Subject Verification
The reference monitor checks the subject against the list of the accessed object.
Authentication
ACLs rely on authentication: the system needs to know the user (subject) to perform the check.
Examples
Unix File ACL
A Unix file stores permissions as an ACL:
- Owner: read, write, execute
- Group: read, execute
- Others: read