Design And Implementation Of P2P IPTV DRM System

This work concentrates on the design of an efficient and scalable grouprekey method for P2P IPTV DRM system. In cable television system, thecopyright is usually sold by a relatively long period of time, such as a month.The content encryption key is renewed monthly by individually transmittingthe encrypted new content encryption key to each authorized member. Thenumber of keys encrypted by this scheme isΘ(N), whereNis the size ofauthorized users. However, this rekey method used in cable television systemis not appropriate for P2P IPTV DRM application. In P2P IPTV DRM system,the minimal division of copyright is a program. The content encryption keyshould be renewed between two consecutive programs to a huge amount ofusers. In this case, new group rekey methods should be designed for P2P IPTVDRM scenario.This paper aims to provide an efficient group rekey scheme in twoaspects, to reduce the number of encryption and to reduce the individualtransmission in the rekey process. To achieve the first goal, we divide themembers into three categories, namely, the fresh members, the rejoinedmembers, and the remaining members, according to their knowledge to thecurrent content encryption key and watching behavior. Different rekeyschemes are adopted for each of these categories. For the fresh members, thecontent encryption key is generated immediately after authorization, whichprovides an initial start point for the fresh members. For the rejoined members,broadcast encryption is used to prevent the revoked users from accessing thenew content encryption key and reduce the number of encryption toΘ(k3logNrejoined), where k is the collusion size. For the remaining members, wepropose a distributed key tree scheme to allow the remaining members tocoordinate a common key among them. By using the distributed key treescheme, the number of keys encrypted in one rekey process is reduced to Θ(logNremaining), whereNremainingis the size of the remaining members. To achievethe second goal, we illustrate how to use multicast mechanism of P2P networkto transmit the new content encryption key for the remaining members oncethe distributed key tree has been constructed. Individual transmission for theremaining members can be eliminated for the remaining members. Thisscheme is implemented in our Ngmylife P2P IPTV system. Realimplementation suggests that our DRM solution adapts well in P2P IPTVsystem even when member size grows large.