On Effective Protection of Security and Privacy in XML Information Brokering

In contrast with the situations when the information seeker knows where the needed data is located, XML Information Brokering System (IBS) needs to help each information seeking query ”locate” the corresponding data source(s). Unlike early information sharing approaches that only involve a small number of databases, new information sharing applications are often assumed to be built atop a large volume of geographically distributed databases, such as emergence health care. Moreover, with increasing concerns on protecting the sensitive and/or proprietary data, the organizations prefer sharing data in a more secure and privacy-preserving manner, instead of establishing a purely full trust relationship and releasing the control over the shared data. In this paper, we explore new information sharing infrastructures to address the new challenges on security, privacy, load balancing, trust management and scalability. In this work, we present a flexible and scalable XML IBS using a broker-coordinator overlay network. Through a novel automaton segmentation scheme, in-network access control, distributed load balancing, trust management and query segment encryption, our system integrates security enforcement and query forwarding while preserving systemwide privacy. We first explore access control deployment strategies in distributed information sharing and the impacts of different deployment strategies on system-wide performance and security. From our study, we are motivated to enforce in-network access control by combining query security checking function with query routing function in Query Brokers and coordinators while maintaining distributed load balancing among peers. We perform a formal presentation of the threat models with a focus on two attacks: attribute-correlation attack and inference attack. Then, we propose a broker-coordinator overlay, as well as three schemes, automaton segmentation scheme, query segment encryption scheme and trust management scheme to share the secure query routing function among a set of brokering servers. We carried out a comprehensive analysis on privacy, end-to-end performance, load balancing and scalability, the proposed system integrate security enforcement, load balancing, trust management between peers and query routing while preserving system-wide privacy with reasonable overhead. Keywords— Privacy, XML, Access Control, load balancing, information sharing, peer to peer, PPIB