11.4  Revocation of Access Rights

Access List – Delete access rights from access list.

    1. Simple

    2. Immediate

Capability List – Scheme required to locate capability in the system before capability can be revoked.

    1. Reacquisition

    2. Back-pointers

    3. Indirection

    4. Keys

Capability-Based Systems

Hydra

    1. Fixed set of access rights known to and interpreted by the system.

    2.  Interpretation of user-defined rights performed solely byuser's program; system provides

         access protection for use of these rights.

Cambridge CAP System

    1. Data capability - provides standard read, write, execute of individual storage segments

         associated with object.

    2. Software capability -interpretation left to the subsystem, through its protected procedures.