Multimedia security in the distributed environment

Multicast is very useful way for large-scale distributing multimedia over the network. It can significantly reduce the bandwidth required to transmit same multimedia over the network to multiple receivers. This property makes multicast competitive and attractive. However, multicast multimedia also provokes challenging security issues because multimedia content in the distributed environment can be illegally copied and redistributed by intended receiver without more effort and no way distinguish who the malicious intended receiver was (some researchers called it traitor tracing). This could lead to serious revenue loss to content providers. It seems the multicast is contradictory to traitor tracing: each receiver in multicast get the same multimedia content if no packet losses occur within the network while to trace traitor everyone should obtain a slightly different content. In this paper, we propose a simple and efficient scheme in order to resolve the issue mentioned above. In our scheme, the content provider generates two different watermarked packets for every data packet firstly. Next, he encrypts every two watermarked packets by two different keys, respectively. Finally, the he multicasts all of encrypted packets with encrypted keys to intended receivers. In the receiver, only one of every pair of encrypted packets is decrypted relying on the ID stored in tamper-resistant hardware. Every receiver obtains unique watermarked packets because every ID is unique. So, the watermarked packets can be used to trace those receivers who make redistribution of received multimedia content illegally.