What is a Reference Monitor responsible for in a system?

A Reference Monitor serves a critical role in enforcing access controls within a system. It acts as a guardian that mediates access requests between subjects (such as users or processes) and objects (like files or devices) to ensure that only authorized actions are permitted. The primary purpose of a Reference Monitor is to maintain system security by ensuring that all access to protected resources is controlled and compliant with established security policies.

When an access request is made, the Reference Monitor checks the security attributes of both the subject and the object involved. If the request adheres to the access control policies set within the system, the Reference Monitor grants access; otherwise, it denies the request. This strict access control mechanism helps in preventing unauthorized access and potential security breaches.

While confidentiality of data, data encryption, and system performance monitoring are important aspects of system security and management, they are not the direct responsibilities of a Reference Monitor. Confidentiality relates to protecting sensitive information from unauthorized disclosure, data encryption involves transforming information into a secure format, and performance monitoring pertains to evaluating the system's operational efficiency. None of these functions specifically characterize the role of the Reference Monitor in enforcing access controls.