Big Brother is in the house (via Hack the Planet): The Chronicle: 11/30/2001: New Company Besieges Colleges With Notices About Copyright Violations
“Once a suspect file is identified, NetPD can find other copies of the same track by looking for similar file names or by matching “digital signatures,” the peculiar arrangement of bits in a file. Mr. Ward says the bulk of NetPD’s business deals with song files, but the company also has software that can identify images. The company also pursues those who share video games and video files.”