UP J2L on Video Streaming

Secure Scalable Video Streaming For Wireless Networks Susie J. Wee

Conventional Approaches to Secure Video Streaming

This section discusses two conventional approaches for secure video streaming. One, a secure video streaming system that uses application-level encryption. The video is first encoded into a bitstream using interframe compression algorithms such as MPEG or H.263 or intraframe compression algorithms such as JPEG or JPEG2000. The resulting bitstream is encrypted, and the resulting encrypted stream is packetized and transmitted over the network using a transport protocol such as UDP. The difficulty with this approach occurs when a packet is lost. Specifically, error recovery is difficult because without the data from the lost packet, decryption and/or decoding may be difficult if not impossible.

Another approach is a secure video streaming system that uses network-level encryption. This system can use the same video compression algorithms as the previous system. However, in this system the packetization can be performed in a manner that considers the content of the coded video and thus results in better error recovery, a concept known to the networking community as application-level framing. For example, a common approach is to use MPEG compression with the RTP transport protocol which is built on UDP. RTP provides streaming parameters such as time stamps and suggests methods for packetizing MPEG payload data o ease error recovery in the case of lost or delayed packets.

Both these approaches are secure in that they transport the video data in encrypted form. However, if network transcoding was needed, it would have to be performed with a method. The transcoding operation is a decrypt, decode, process, re-encode, and re-encrypt process. The computational requirements of this operation can be reduced by incorporating efficient transcoding algorithms in place of the decode, process, and re-encode modules. However, even improved transcoding algorithms have computational requirements that are not well-suited for transcoding many streams in a network node. Furthermore, a more critical drawback stems from the basic need to decrypt the stream for every transcoding operation. Each time the stream is decrypted, it opens another possible attack point and thus increases the vulnerability of the system. Thus, each transcoder further threatens the security of the overall system.

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posted by LJ Regalado @ 4:10 PM