Accesscontrol

Access control is a method for restricting access to resources based on subject identity, roles, or other attributes. It ensures that only authorized subjects can perform permitted actions on objects while unauthorized actions are denied. Access control applies to physical resources, such as doors, facilities, and security checkpoints, as well as logical resources, such as files, databases, networks, and cloud services.

In a typical system, a user or device is identified and authenticated, and an authorization decision is made before access is granted or denied. Enforcement occurs at a policy enforcement point, such as a door reader, a file system, or an application interface.

Common models include discretionary access control (DAC), mandatory access control (MAC), role-based access control (RBAC), and attribute-based access control (ABAC). DAC allows resource owners to set permissions; MAC enforces site-wide or class-based policies; RBAC assigns permissions by role; ABAC makes decisions from attributes of the user, resource, and context. Access control policies are implemented via mechanisms such as access control lists (ACLs), capability-based systems, or policy engines.

Effective access control emphasizes least privilege, need-to-know, and separation of duties, along with rigorous auditing and review. In practice, access control integrates with identity management, authentication methods, and authorization services, and is a core component of security architectures for on-premises, cloud, and hybrid environments.