11 - Scalable Encryption and Multi-Access Control for Multimedia

Abstract

This chapter provides an overview of scalable encryption and multi-access encryption for digital rights management (DRM) and other multimedia applications. Both, scalable encryption and multi-access encryption work with scalable multimedia coding. A framework for multi-access encryption for scalable coding is proposed by Zhu, Li, and Feng. A scalable codestream is organized on some fundamental building blocks known as Scalable Building Blocks (SBBs). The chapter presents MPEG-4 FGS and JPEG 2000 scalable coding standards, and illustrates scalable encryption technologies. MPEG-4 FGS encodes a video sequence into two layers: a non-scalable base layer that offers the lowest quality and bitrate for the scalable codestream, and a scalable enhancement layer that offers enhancement in a large range of signal-to-noise ratios (SNRs) and bitrates to the base layer. JPEG 2000 is a wavelet-based image coding standard. Scalable encryption ensures that the encrypted codestream maintains a certain level of scalability. Scalable granularity after encryption is a key consideration in the design. Some scalable encryption schemes are syntax compliant to ensure that different users can extract different representations from a single encrypted codestream to fit their respective applications, and that a user can consume only the particular representations he or she is authorized to. The chapter ends with a note that as it is a new research area, many issues still remain to be studied and optimized in future research endeavors.