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The object-capability model is a computer security model. A capability describes a transferable right to perform one (or more) operations on a given object. It can be obtained by the following combination:
- An unforgeable reference (in the sense of object references or protected pointers) that can be sent in messages.
- A message that specifies the operation to be performed.
The security model relies on not being able to forge references.
- Objects can interact only by sending messages on references.
- A reference can be obtained by:
- Initial conditions: In the initial state of the computational world being described, object A may already have a reference to object B.
- Parenthood: If A creates B, at that moment A obtains the only reference to the newly created B.
- Endowment: If A creates B, B is born with that subset of A's references with which A chose to endow it.
- Introduction: If A has references to both B and C, A can send to B a message containing a reference to C. B can retain that reference for subsequent use.
In the object-capability model, all computation is performed following the above rules.
Advantages that motivate object-oriented programming, such as encapsulation or information hiding, modularity, and separation of concerns, correspond to security goals such as least privilege and privilege separation in capability-based programming.[1][2]
The object-capability model was first proposed by Jack Dennis and Earl C. Van Horn in 1966.[3]
- ^ Miller, Mark Samuel (May 2006). "Robust Composition: Towards a Unified Approach to Access Control and Concurrency Control". erights.org. Baltimore, Maryland. Retrieved 28 July 2013.
- ^ Mark S. Miller; Ka-Ping Yee; Jonathan S. Shapiro (2003). "Capability Myths Demolished" (PDF). Technical Report SRL2003-02. Systems Research Lab, Johns Hopkins University.
{{cite journal}}: Cite journal requires|journal=(help) - ^ [1] citing: J.B. Dennis, E.C. Van Horn. “Programming Semantics for Multiprogrammed Computations.” Communications of the ACM, 9(3):143–155, March 1966.