A system for authenticating a physical object includes an enrolment device, an authentication device, and a storage for storing authentication data. The enrolment device includes an input for receiving a property set Y of the object measured using a measurement procedure. A processor is used for creating a property set I from the measured property set Y that meet a predetermined robustness criterion. It then creating a property set A from the property set I that includes less information on the actual properties than property set Y, and finally generates a control value Vin dependence on properties of the property set A. An output is used for supplying the control value to the storage as part of the authentication data. The enrolment device operates in an analogous way.