Encryption and Authentication for Scalable Multimedia: Current State of the Art and Challenges.
Scalable coding is a technology that encodes a multimedia signal in a scalable manner where various representations can be extracted from a single codestream to fit a wide range of applications.
Many new scalable coders such as JPEG 2000 and MPEG-4 FGS offer fine granularity scalability to provide near continuous optimal tradeoff between quality and rates in a large range.
This fine granularity scalability poses great new challenges to the design of encryption and authentication systems for scalable media in Digital Rights Management (DRM) and other applications.
It may be desirable or even mandatory to maintain a certain level of scalability in the encrypted or signed codestream so that no decryption or re-signing is needed when legitimate adaptations are applied.