Purpose based access control of complex data for privacy protection

As privacy becomes a major concern for both consumers and enterprises, many research efforts have been devoted to the development of privacy protecting technology. We recently proposed a privacy preserving access control model for relational databases,where purpose information associated with a given data element specifies the intended use of the data element. In this paper, we extend our previous work to handle other advanced data managementsystems, such as the ones based on XML and the ones based on the object-relational data model. Another contribution of our paper isthat we address the problem of how to determine the purpose forwhich certain data are accessed by a given user. Our proposedsolution relies on the well-known RBAC model as well as the notionof conditional role which is based on the notions of role attributeand system attribute.