The present invention relates generally to steganography. In one implementation we provide a method comprising: receiving optical scan data representing at least a portion of a physical object. The physical object includes information steganographically hidden thereon, and the information includes at least some information indicating an operation of the physical object. The method also includes analyzing the optical scan data to obtain the information, and based at least in part on the information determining whether the physical object is operating as expected. Of course, other implementations are provided as well.