What are the most important access control models for DBMS?

1 Discretionary Access Control

Discretionary access control (DAC) is a model that allows the owner or creator of a data object to grant or revoke access rights to other users or groups. DAC is based on the principle of least privilege, which means that users should only have the minimum level of access necessary to perform their tasks. DAC is flexible and easy to implement, but it also poses some risks, such as unauthorized data sharing, malicious modification, or accidental deletion.

2 Mandatory Access Control

Mandatory access control (MAC) is a model that enforces a predefined security policy based on the classification of data and users. MAC assigns security labels to data objects and clearance levels to users, and only allows access if the user's clearance level is equal to or higher than the data's security label. MAC is more secure and robust than DAC, but it also requires more administration and maintenance, and it may restrict legitimate access or collaboration.

3 Role-Based Access Control

Role-based access control (RBAC) is a model that assigns access rights to users based on their roles or functions in an organization. RBAC defines a set of roles, each with a specific set of permissions, and assigns users to one or more roles. RBAC simplifies the management of access rights, as it reduces the number of individual decisions and allows for easy modification of roles and permissions. RBAC also supports the principle of separation of duties, which means that no single user can perform conflicting or sensitive tasks.

5 Hybrid Access Control

Hybrid access control is a model that combines two or more of the above models to achieve a balance between security and flexibility. Hybrid access control can leverage the strengths and mitigate the weaknesses of different models, depending on the data and user characteristics and the security objectives. For example, a hybrid model can use MAC for highly sensitive data, RBAC for general data, and ABAC for special cases or exceptions. Hybrid access control, however, can also introduce more complexity and inconsistency, and it may require careful integration and coordination of different models.