An authentication system and method is presented for authenticating a first party to a second party, where an operation is performed on condition that the authentication succeeds. The authentication method verifies whether the first party is authenticated. If the first party is not authenticated, then it is determined if the first party qualifies for a sub-authorization. The sub-authorization depends on a value of a grace-counter associated with a number of times that first parties have been qualified for the sub-authorization. If the first party qualifies for the sub-authorization, the operation is performed and the grace counter is decremented. If the first party is authenticated, then the grace counter is set to a predetermined number.