Data is encoded for identification and labeling using a multitude of nano-electro-mechanical structures formed on a substrate. The number of such structures, their shapes, choice of materials, the spacing therebetween and the overall distribution of the structures result in a vibrational pattern or an acoustic signature that uniquely corresponds to the encoded data. A first group of the structures is formed in conformity with the design rules of a fabrication process used to manufacture the device that includes the structures. A second group of the structures is formed so as not to conform to the design rules and thereby to undergo variability as a result of the statistical variations that is inherent in the fabrication process.