SECURITY MODEL
A computer security model is a system for identifying and enforcing security policies. A security model may be established upon a formal model of access rights, a model of computation, a model of dispersed computing, or no particular theoretical grounding at all.
In computer security, an access control list (ACL) is a list of permissions fond of to an object. The lists identify who or what is allowable to access the object and what operations are allowable to be execute on the object. In a usual ACL, each entrance in the list identifies a subject and an operation: for illustration, the entry (Alice, delete) on the ACL for file WXY gives Alice authorization to delete file WXY.