A method for authenticating an object includes positioning a millimeter-wave transceiver relative to an object which contains a metamaterial marking. A transmit signal is transmitted from the millimeter-wave transceiver in the direction of the metamaterial marking, wherein the transmit signal is converted based on the metamaterial marking into a receive signal which has a first characteristic and is emitted in the direction of the millimeter-wave transceiver. The receive signal is received and processed by the millimeter-wave transceiver in order to capture the first characteristic. First comparison information is generated based on the first characteristic and an authentication of the object is carried out based on the first comparison information.