Take-grant protection model
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The take-grant protection model is a formal model used in the field of computer security to establish or disprove the safety of a given computer system that follows specific rules. It shows that for specific systems the question of safety is decidable in linear time, which is in general undecidable.
The model represents a system as directed graph, where vertices are either subjects or objects. The edges between them are labeled and the label indicates the rights that the source of the edge has over the destination. Two rights occur in every instance of the model: take and grant. They play a special role in the graph rewriting rules describing admissible changes of the graph.
There is a total of four such rules: The take rule allows a subject to take rights of another subject, while the grant rule allows a subject to grant own rights to another subject. The create rule allows every subject to create new nodes, while the remove rule allows a subject to remove rights it has over another object.
Using the rules of the take-grant protection model, one can reproduce in which states a system can change, with respect to the distribution of rights. Therefore one can show if rights can leak with respect to a given safety model.
[edit] References
- Lipton, Richard J.; Snyder, Lawrence (1977). "A Linear Time Algorithm for Deciding Subject Security" (PDF). Journal of the ACM 24 (3): 455-464.
- Bishop, Matt (2004). Computer security: art and science. Addison-Wesley.
