Abstract: In a general aspect, unique unclonable physical identifiers are applied and used. A method of applying the unique marker can include receiving an object having a surface feature and forming a unique marker on the surface feature of the object. The unique marker includes a distribution of elements and conforms with a morphology of the surface feature. The method further includes extracting orientation information from the unique marker. The orientation information can indicate relative spatial orientations of the respective elements. The method additionally includes generating a unique code for the object based on the orientation information. The surface feature can be facets, surface patterns, textures, or other indentations of the object. The surface feature can include a region of the object that is susceptible to tampering.