Secure Scalable Multimedia Streaming

In order to adapt streaming multimedia data to user needs and network conditions, modern coding systems provide scalability along different planes (e.g., bit-rate vs. distortion, frame-rate, resolution, etc.). However, the transcoding process which enables content scaling is inherently insecure since it generally requires direct access to the multimedia data. If the data is encrypted to ensure confidentiality, the transcoding server requires the decryption key in order to scale the data. This represents an unacceptable security risk if the transcoding server resides in an untrusted domain.

This project aims to resolve the inherent conflict between multimedia scalability and security, by way of a Secure Scalable Multimedia Streaming (SSMS) framework. This framework involves structuring the encrypted data using XML and adding metadata which provides the necessary information for the transcoder to scale the content without having to decrypt it. This allows for end-to-end security while maintaining full scalability.

Previous work in the literature has focused on Secure Scalable Streaming (SSS) of video content [1]. This project involves implementation of SSS for video and expansion of the concept to general multimedia data (e.g., text, slides, etc.). An adaptation engine wad developed, taking advantage of the Microsoft Office OpenXML format used in the Microsoft PowerPoint 2007 presentation software. The slides, visual design elements, vector graphics, and text boxes are reduced in size so that they maintain the same layout positioning and relative size, but features such as object outlining and borders effectively become larger and more visible on small displays. Furthermore, when desired, text is removed from bulleted lists in order to make more effective use of screen real estate. Processing is performed using unencrypted metadata, while content remains encrypted.

Demo of secure MPEG-4 frame-rate scaling »

Secure MPEG-4 Frame-rate Scaling System Documentation »

Secure, XML-Based Presentation Slide Adaptation for
Universal Access Technical Report »

[1] J. Chakareski, J. G. Apostolopoulos, S. Wee, W. Tan, and B. Girod, "Rate-Distortion Hint Tracks for Adaptive Video Streaming," IEEE Transactions on Circuits and Systems for Video Technology, vol. 15, no. 10, pp 1257 - 1269, Oct. 2005.

Team Members: Karl Martin, Cindy Guo