The present invention relates to a method for authenticating and/or identifying persons, objects, service systems or computer programs, in which a static, unchanging security feature that is characteristic of the person, the object, the service system or the computer program, is created or used, which is subsequently altered under the influence of an unforeseeable factor and thereby converted into a dynamic security feature. Positive authentication is obtained, when the dynamic security feature has at least been partly changed by a dynamic factor between two query times in comparison with the static security feature stored in the storage medium, wherein the static security feature stored in the storage medium corresponds to the most recently updated, altered dynamic security feature from the last query time. Further, the invention relates to an authentication system, in which dynamic security features originate from a static security feature.