Multimedia Access Control Using RDF Metadata

Abstract

The Synchronized Multimedia Integration Language (SMIL) [Aya01] is an W3C [W3C03] specification for authoring multimedia documents. Although SMIL has XML like syntactic constructs, unlike XML, SMIL compositions have an intended interpretation stemming from intuitive notions of playing out many media streams relative to each other. Thus, more than one SMIL syntactic expression can represent a multimedia composition with the same intended semantics. In this work we propose a normal form for SMIL objects that allows to specify security policies that are independent of representational syntax. We also show how to represent access control and QoS polices applicable to multimedia compositions by decorating SMIL compositions with RDF [KC03] statements. Our RDF statements are based on an RDF structure tailored to represent known security paradigms such as Discretionary, Mandatory, and Role-Based Access Control. Once the security paradigm is chosen and the SMIL document is decorated with security and QoS specifications, we show how to create secure views of the SMIL document. We call these views secure normal forms. Next, we show how a secure multimedia server can use these views to provide secure runtime environment.