1. A computer-assisted method for identifying a person, comprising: receiving a digitally watermarked digital facial portrait of the person, the digital facial portrait embedded with at least one digital watermark identifying payload data linking the digital facial portrait to the person portrayed in the digital facial portrait; receiving results of comparison between the digital facial portrait of the person and the person presenting the digitally watermarked digital facial portrait; retrieving the at least one digital watermark in response to receiving comparison results that the person portrayed in the digital facial portrait is the person presenting the digitally watermarked digital facial portrait; and determining that the digital facial portrait is authentic based on the retrieved at least one digital watermark.