Capabilitiesbased

Capabilitiesbased, in the context of computer security and access control, refers to a model in which authority to access resources is carried by unforgeable tokens called capabilities. A capability embodies a reference to a resource together with the operations it permits. A process can perform actions on a resource only if it possesses a suitable capability, and capabilities can be transferred or delegated to other agents to grant them access. This contrasts with traditional models that rely on centralized access control lists or policies attached to subjects or objects.

Key properties of capabilitiesbased systems include unforgeability, delegation, and fine-grained control. Unforgeability ensures that only holders of a valid capability can exercise rights. Delegation allows authorities to be passed along without renegotiating permissions with a central authority. Revocation remains a design challenge, as revoking a capability requires mechanisms such as expiry, revocation lists, or capability-scoped ownership transfers. The model supports least-privilege principle and durable, decoupled interaction among components.

Implementation approaches vary. Hardware-supported capability machines provide architectural enforcement of capabilities. Software-based approaches use object capabilities, capability lists, or cryptographic tokens to protect references to resources. Prominent ecosystems and research include object-capability models in languages and systems, capability-based operating systems, and distributed platforms that emphasize secure delegation and isolation.

Applications benefit from fine-grained access control, scalable security in distributed systems, and modular design that minimizes trusted code. Challenges include managing durable revocation, ensuring capability confidentiality, and preventing capability leakage. See also capability-based security and the object-capability model.