Abstract: Digitial Libraries (DL) introduce several challenging requirements with respect to the formulation,specification, and enforcement of adequate data protection policies. Unlike conventional databaseenvironments, a DL environment typically is characterized by dynamic user population, often making accesses from remote locations, and by an extraordinary large amount of multimedia information, stored in avarety of formats. Moreover, in a DL environment, access policies are oftcn specified based on userqualifications and characteristics, rather than user identity (for example,a user can be given access to an Rrated video only if he/she is older than 18 years). Another crucial requirement is the support for contentdependent authorizations on digital library objects (for example, all documents containing discussions onhow to operate guns must be made available only to users who axe 21 or older). Traditional authorizationmodels are not fully adequate to meet access control requirements typical to DL. In this talk, we present acontent-based authorization model suitable for a DL environment. The most innovative features of suchmodel are: (l) flexible specifications of authorizations based on the qualifications and characteristics ofusers (including positive and negative authorizations); (2) both content-dependent and content-independentaccess contfol to DL objects; (3) varying granularity of authorization objects ranging from sets of DLobjects to specific portions of objects.

中图分类号: 

• TP311.1