Attribute-based access control (ABAC) defines a new access control paradigm whereby access rights are granted to users through the use of policies which combine attributes together. The policies can use any type of attributes (user attributes, resource attributes, environment attribute etc.). Attribute values can be set-valued or atomic-valued. Set-valued attributes contain more than one atomic values. Examples are role, project. Atomic-valued attributes contains only one atomic value. Examples are clearance, sensitivity. Attributes can be compared to static values or to one another thus enabling relation-based access control.