A system and method distribute licenses for copyrighted material separate from the copyrighted material itself. A producer or “vendor” of copyrighted material registers the material with a License Provider. The License Provider returns an encryption code for the producer to attach to the materials...http://www.google.com.tw/patents/US7062468?utm_source=gb-gplus-share專利 US7062468 - Licensed digital material distribution system and method
