U3.2 Access Control Structures

U3.2 Access Control Structures

1. Access Control Matrix

   • Based on a grid. Subjects on the side, objects accross
     • Not practical for large organisations with 100's of subjects and 10000's of objects, to many empty spaces and wasted memory

2. Access Control List

   • Concentrate on objects
     • ACL for object is stored within the object
       • Checked before access is granted
     • More widely used than Matrix
   • Used by UNIX
   • Main disadvantage is checking the list is time consuming, if access is revoked for a user then every object has to be checked for that user

3. Capability list

   • Focus on access rights of Subjects
     • Concentrate on the rows of a matrix
   • Used in databases
   • Disadvantages
     • difficult to ascertain the rights to an object
     • difficult to revoke permissions if owner has granted certain rights to subjects

4. How does the Reference Monitor ascertain which subjects have access to which objects?

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