Introduction
The privacy of personal information on the Internet has become a major concern for governments, businesses, media, and the public. Opinion surveys consistently show that privacy concerns are a leading impediment to the further growth of web-based commerce. Initial efforts by web sites to disclose their privacy policies have had limited impact because these policies were often too lengthy for users to read and were written in a language too difficult for users to understand. Platform for Privacy Preferences (P3P), developed by the World Wide Web Consortium (W3C), is the most significant effort underway to enable users to gain more control over what information a web site collects. It provides a way for a web site to encode its data-collection and data use practices in a machine-readable XML format, known as a P3P policy, which can be programmatically compared against a userâ„¢s privacy preferences. The current P3P standard only provides a mechanism for users to check a web siteâ„¢s privacy policy before they release personal information to the site; mechanisms for enforcing that sites act according to their stated policies are beyond its scope. In this paper, we propose a server-centric architecture for P3P that reuses database technology, as opposed to the prevailing client-centric implementations based on specialized engines. The server-centric architecture has several advantages including: setting up the infrastructure necessary for ensuring that web sites act according to their stated policies, allowing P3P to be deployed in thin, mobile clients that are likely to dominate Internet access in the future, and allowing site owners to refine their policies based on the privacy preferences of their users. Our experiments ind icate that the proposed server-centric architecture performs significantly better than the sole public-domain client-centric implementation. These experiments also show that the proposed architecture has the necessary performance for it to be used in practical deployments of P3P.
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