Implementations of Access Matix
Global table:
- A set of ordered triples <domain, object, right-set>. (a cell in the martix).
- Difficult to take advantage of grouping of objects and/or domains (if a particular object can be read by everyone it must have a separate entry in every domain).
- Table is usually large (storage).
Access control list:
- A list of sets (one per object). Each set has ordered pairs <domain, right-set>. (a column in the matrix).
- Domains with no access to this objects can be discarded.
- Can be improved by having a default set that applies to all objects.