Multimedia content delivery applications are becoming widespread thanks to increasingly cheaper access to high bandwidth networks. Also, the pervasiveness of XML as a data interchange format has given origin to a number of standard formats for multimedia, such as SMIL for multimedia presentations, SVG for vector graphics, VoiceXML for dialog, and MPEG-21 and MPEG-7 for video. Innovative programming paradigms (such as the one of web services) rely on the availability of XML-based markup and metadata in the multimedia flow in order to customize and add value to multimedia content distributed via the Net. In such a context, a number of security issues around multimedia data management need to be addressed. First of all, it is important to identify the parties allowed to use the multimedia resources, the rights available to the parties, and the terms and conditions under which those rights may be executed: this is fulfilled by the Digital Rights Management (DRM) technology. Secondly, a new generation of security and privacy models and languages is needed, capable of expressing complex filtering conditions on a wide range of properties of multimedia data. In this chapter, we analyze the general problem of multimedia security. We summarize the most important XML-based formats for representing multimedia data, and we present languages for expressing access control policies. Finally, we introduce the most important concepts of the DRM technology.
THE NEW EMERGENT MULTIMEDIA CONTENT AND DIGITAL RIGHTS MANAGEMENT
