Renewable traitor tracing

Abstract From the Canadian patent

A system, method, and computer program product to renewably prevent traitors in a broadcast encryption system from re-using compromised keys. A license agency assigns individual receivers a set of Sequence Keys preferably at manufacture, and assigns Sequence Key Blocks (SKBs) to protected content files to be distributed. The files may be distributed on prerecorded media and typically include several file modifications . The particular modifications in a pirated version of a file can help identify which traitors contributed to its theft. SKBs assigned to new files distributed after traitors have been identified cannot be usefully processed using the compromised keys employed in …