Buffer Occupancy Feedback Security Control and Changing Encryption Keys to Protect MOD Services

Abstract

We present an effective security control for multimedia streaming in public network via buffer-occupancy feedback controls of client’s playback buffer. There is a wide variety of multimedia-on-demand (MOD) applications can benefit from this end-to-end security control to protect the streaming data. Because the encryption/decryption for video packets are time-consuming process, our observation is that the playback buffer occupancy (PBO) can simply indicate the time availability to adjust the security level to affect the sending rate for the packet delivery. That is to say, adjusting security level can be applied further to keep the PBO away from buffer overflow and underflow. Therefore, we propose a feedback control of PBO not only to protect the MOD services from eavesdroppers, but also maintain the playback quality. To further boost the protection, we also apply Diffie-Hellman key negotiation method to provide the dynamic key changes while the PBO is controlled at a stable range for a long period. Moreover, due to the network uncertainty, different content delivery in MOD service will preserve different running PBOs. Then, they may have different applied security levels and key changes in service sessions. It will make eavesdroppers more difficult to recover the whole encrypted media data. In this paper, we also demonstrate the performance of encryption protection and preserved playback quality in our proposed schemes by experiments on a true VOD system with well-known encryptions of DES, 2DES and 3DES.

The work was partially done while the author was visiting the Institute of Information Science, Academia Sinica, Taiwan in 2005 and supported by National Science Council, Project No. NSC 94-2213-E-130-001, Taiwan.