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Privacy Preserving Data Portals

Information in a Web portal often is an integration of data collected from multiple sources. A typical example is the concept of one-stop service, for example, a single health portal provides a patient all of her/his health history, doctor’s information, test results, appointment bookings, insurance, and health reports. This concept involves information sharing among multiple parties, for example, hospital, drug store, and insurance company. On the other hand, the general public, however, has growing concerns about the use of personal information. Samarati (2001) shows that linking two data sources may lead to unexpectedly revealing sensitive information of individuals. In response, new privacy acts are enforced in many countries. For example, Canada launched the Personal Information Protection and Electronic Document Act in 2001 to protect a wide spectrum of information (The House of Commons in Canada, 2000). Consequently, companies cannot indiscriminately share their private information with other parties. A data portal provides a single access point for Web clients to retrieve data. Also, it serves a logical point to determine the trade-off between information sharing and privacy protection. Can the two goals be achieved simultaneously? This chapter formalizes this question to a problem called secure portals integration for classification and presents a solution for it. Consider the model in Figure 1. A hospital A and an insurance company B own different sets of attributes about the same set of individuals identified by a common key. They want to share their data via their data portals and present an integrated version in a Web portal to support decision making, such as credit limit or insurance policy approval, while satisfying two privacy requirements: