Secure Scalable Multimedia Streaming Karl Martin Multimedia Lab Dept. of Electrical and Computer Eng. University of Toronto

2 I. Introduction Communications becoming more multimedia in nature – images, video, and text The key to Universal Multimedia Access (UMA) is content scalability Efficient content streaming is achieved via a transcoding server which scales the content to meet user needs and network conditions

3 I. Introduction Possibly Untrusted Scalable Content End-to-end Security + Scalibility?

4 I. Introduction Problem: How do we maintain scalability while keeping the content confidential? Scalability has traditionally been seen to be in fundamental conflict with security Can we encrypt the content and subsequently have a transcoding server scale it without knowledge of the decryption key?

5 II. Secure Scalable Multimedia Streaming (SSMS) Structure the content using XML (MPEG-21 Digital Item) Structure matches the packetized scalability components of the content Separately encrypt scalability components using progressive encryption Include unencrypted metadata hint tracks which instruct the transcoder how to scale the content without decryption

6 II. SSMS – Video Example OR

7 II. SSMS – Video Example Scalability modalities: frame-rate, distortion, resolution, etc. Hint tracks allow transcoding server to truncate and remove appropriate packets without decryption

8 II. SSMS – Generic Media Concept to be extended to images (e.g., JPEG 2000) and documents XML-based documents (e.g., MS Office Open XML, OpenDocument Format) Document schema used to determine supported scaling modalities Content pre-analysis used to determine discrete scaling points (e.g., levels of summarization) SSMS scheme will also enable implementation of complex security policies