digital fingerprinting

Similar to a netary public, this is one way of attaching information to a Web document to protect intellectual property. It works like this: Registered users send files to a company that specializes in digital fingerprinting; it generates a digital fingerprint on the file, assigning it a time stamp that shows when the file was first in use. Any change to the file (even one character or space) will render the fingerprints unmatchable. 

Historical perspective: In 2008, Michael Kwun, Google's managing counsel for litigation, said in an interview at its Silicon Valley headquarters that the company already offers copyright holders several technologies to identify pirated video. But he declined to specify a timeline for when Google will make so-called "video fingerprinting" technologies available to media rights owners.