Let’s break down Discretionary Access Control (DAC) in a way that’s easy to grasp for those new to IT.
Imagine you create a document on your personal computer. You, as the owner of that document, have the power to decide who else can open it, edit it, or even just see its name in the folder. This fundamental concept of an owner deciding who gets access is the core idea behind Discretionary Access Control (DAC). The word “discretionary” here means it’s up to the owner’s judgment or discretion.
In the world of IT, DAC is a common and foundational access control model. It operates on the principle that the creator or owner of a resource (like a file, folder, or even a database table) has the authority to grant or revoke access to other users or groups. These permissions are often managed through Access Control Lists (ACLs) associated with each resource. Think of an ACL as a list attached to the file that spells out exactly who has what kind of permission.
Operating systems like Windows and macOS heavily rely on DAC for managing file and folder permissions. When you right-click on a file and go to “Properties” or “Get Info,” you’ll typically find a section dealing with permissions – this is DAC in action. You, as the owner (or an administrator with sufficient rights), can modify these permissions as you see fit.
Databases also frequently employ DAC. Database administrators or the creators of specific tables can grant or revoke privileges like SELECT (viewing data), INSERT (adding data), UPDATE (modifying data), and DELETE (removing data) to different users or roles.
Even in modern cloud environments, while more sophisticated models like RBAC are increasingly prevalent, DAC often plays a role at a lower level or in conjunction with other mechanisms. For instance, a user might own the files they upload to a cloud storage service and can then share those files with specific individuals using DAC-like permissions.