The Graham-Denning Model

The Graham-Denning Model is a security model designed to control access to objects in a computer system. It was proposed by R. M. Graham and D. R. Denning in 1972. The model is particularly focused on access control for secure systems.

The Graham-Denning Model introduces the concepts of subjects (entities that can access objects) and objects (resources to be protected). The model defines a set of rights or operations that can be performed on objects, such as create, delete, and read.

Key features of the Graham-Denning Model include:

  1. Access Control Matrix (ACM): The model uses an access control matrix to represent the access rights of subjects to objects. The matrix shows which subjects have which rights on which objects.
  2. Rules for Access Control:
    • Control State: Each subject and object has an associated control state that determines the access rights.
    • Eight Rules: The model defines eight rules that specify how subjects can request changes to the access control matrix.
  3. Security Goals:
    • Right of Access Rule: Ensures that a subject can only grant access rights to others if it has the right to those access rights.
    • Right of Transfer Rule: Ensures that a subject can only transfer access rights to others if it has those rights.

The Graham-Denning Model aims to provide a structured approach to access control in computer systems, contributing to the overall security of the system by preventing unauthorized access and ensuring the integrity of the access control matrix.

Keep in mind that there may be further developments or variations of access control models in the field of computer security.