Because it governs all potential communication between entities, the need of security policies is nowadays increasingly growing and not to be any more proved. Moreover, in today's technological society and to allow applications perpetuity, communication networks must support the collaboration between entities to face up any unavailability or flinching. On others hands, it must allow to a user without any administrative prerogatives to obtain the ability to grant some authorizations. That is what we call delegation. In this paper, we propose a delegation model as well as its keys activities management. The main contribution concerns revocation. In fact, we propose five dimensions allowing the definition of sixteen different revocation schemes.