An authentication method includes receiving, at a processor, a signal representing an image of a serialization code and multiple flecks of a label, the flecks having a random distribution. The processor detects the serialization code and applies a modification to the image to produce a modified image. A subset of flecks of the modified image is detected, and metrics associated with each fleck from the subset of flecks are identified. The identified metrics are compared with metrics associated with a unique signature, and a message is displayed, via a user interface, indicating an authenticity of the label based on the comparison.