Privacy-Preserving Reasoning on the Semantic Web (Poster)


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Privacy-Preserving Reasoning on the Semantic Web (Poster)

  1. 1. Incomplete knowledge Center for Computational Intelligence, Learning, and Discovery Artificial Intelligence Research Laboratory Department of Computer Science Acknowledgements : This work is supported in part by grants from the National Science Foundation (IIS-0639230). Privacy-Preserving Reasoning on the Semantic Web Jie Bao, Giora Slutzki, and Vasant Honavar 3- Concrete Strategies 2 – General Strategy Highlights : <ul><li>The Problem: can we share knowledge / answer queries about a knowledge base without compromising its privacy </li></ul><ul><li>The Solution: hiding private knowledge as if it is incomplete knowledge under the open world assumption </li></ul>1 – Problem Description <ul><li>WEB PRIVACY : </li></ul><ul><li>Required by Copyright, Commercial Needs, Personal Privacy … </li></ul><ul><li>Applications: Web Service, Medical System, E- Commerce… </li></ul><ul><li>Syntactical specification: Policy languages, e.g., KAoS, xACML. </li></ul><ul><li>REASONING WITH HIDDEN KNOWLEDGE : </li></ul><ul><li>To verify the correctness and consistency of security policies </li></ul><ul><li>To avoid overly restrictive protection on data or knowledge </li></ul><ul><li>To allow flexible safe usage of the same knowledge base to multiple users </li></ul>Locally visible : Has date Query: Has date? Answer : Unknown Query: Has travel? Answer: Unknown Query: Busy (has activity)? Answer : Yes Hidden knowledge <ul><li>STRATEGY : </li></ul><ul><li>Open World Assumption: knowledge base may be incomplete </li></ul><ul><li>Answer “Unknown” to both incomplete knowledge and hidden knowledge </li></ul><ul><ul><li>Querying agent cannot distinguish between them </li></ul></ul><ul><ul><li>Hidden knowledge is protected as if it is incomplete knowledge </li></ul></ul>EXAMPLE : a calendar ontology FOR HIERARCHIES : FOR DESCRIPTION LOGICS (AND OWL) : Reasoning Strategy : Safety Scope : “ safe” graph “ unsafe” graph Basic idea : Problem reduces to graph reachability analysis Basic idea : Ensure that answers to queries will NOT give knowledge beyond Critical visible knowledge (i.e., K v about the signature of K h .) K h K v Critical visible knowledge K vc C ⊑ D C ⊑  R. D G ⊑ H <ul><ul><li>Reasoning Strategy & Safety Scope : ensure that K v -K vc + Q Y is local w.r.t. Sig( K vc ) (locality defined by [Grau et al., 2007] ) </li></ul></ul>Reference: Bao, J., Slutzki, G., and Honavar, V. (2007). Privacy-Preserving Reasoning on the Semantic Web . In Web Intelligence 2007. a b c d e a b c d e