Logical Functions

Enforcer provides the following cateogries of Oasis functions accessible from ALFA. These functions can be used as part of an expression inside a policy.

• String Functions
• Attribute Bags
• Time
• Logical
• Arithmetic

To make use of these functions from inside an ALFA file, use the import statement:

import Oasis.Functions
import Enforcer.Functions

Logical

Namespace : Oasis.Functions

AtLeastNAreTrue

function AtLeastNAreTrue = "urn:oasis:names:tc:xacml:1.0:function:n-of"
                         : numberToBeTrue:integer valuesToCheck:boolean* -> boolean

Will return true if a minimum number of boolean expressions evaluate to true. The first parameter is the minimum number of expressions that must be true, and the remaining parameters are boolean expressions to be considered.

Example

AtLestNAreTrue(2, Subject.AuthenticationScheme == 'Fido',
                  Subject.AuthenticationScheme == 'TOTP',
                  Subject.AuthenticationScheme == 'TextPassword');