Which of the following statements are true about capability-based security?

A.
It is a concept in the design of secure computing systems, one of the existing security models.

B.
It is a computer security model based on the Actor model of computation.

C.
It is a scheme used by some computers to control access to memory.

D.
It is a concept in the design of secure computing systems.

Explanation:
Capability-based security is a concept in the design of secure computing systems. A capability (known in some systems as a key) is a communicable, unforgivable token of authority. It refers to a value that references an object along with an associated set of access rights. A user program on a capability-based operating system must use a capability to access an object. Capability-based security refers to the principle of designing user programs such that they directly share capabilities with each other according to the principle of least privilege, and to the operating system infrastructure necessary to make such transactions efficient and secure.

Although most operating systems implement a facility which resembles capabilities, they typically do not provide enough support to allow for the exchange of capabilities among possibly mutually untrusting entities to be the primary means of granting and distributing access rights throughout the system. A capability-based system, in contrast, is designed with that goal in mind. Answer options B, C, and A are incorrect. These are not correct statements about capability-based security.