Quantifying Privacy Leakage through Answering Database Queries

  • Authors:
  • Tsan-sheng Hsu;Churn-Jung Liau;Da-Wei Wang;Jeremy K.-P. Chen

  • Affiliations:
  • -;-;-;-

  • Venue:
  • ISC '02 Proceedings of the 5th International Conference on Information Security
  • Year:
  • 2002

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Abstract

We assume a database consists of records of individuals with private or sensitive fields. Queries on the distribution of a sensitive field within a selected population in the database can be submitted to the data center. The answers to the queries leak private information of individuals though no identification information is provided. Inspired by decision theory, we present a quantitative model for the privacy protection problem in such a database query or linkage environment in this paper. In the model, the value of information is estimated from the viewpoint of the querier.To estimate the value, we define the information state of the data user by a class of probability distributions on the set of possible confidential values. We further define the usefulness of information based on how easy the data user can locate individuals that fit the description given in the queries. These states and the usefulness of information can be modified and refined by the user's knowledge acquisition actions. The value of information is then defined as the expected gain of the privacy receiver and the privacy is protected by imposing costs on the answers of the queries for balancing the gain.