Anonymizing tables

  • Authors:
  • Gagan Aggarwal;Tomás Feder;Krishnaram Kenthapadi;Rajeev Motwani;Rina Panigrahy;Dilys Thomas;An Zhu

  • Affiliations:
  • Stanford University;Stanford University;Stanford University;Stanford University;Stanford University;Stanford University;Stanford University

  • Venue:
  • ICDT'05 Proceedings of the 10th international conference on Database Theory
  • Year:
  • 2005

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Abstract

We consider the problem of releasing tables from a relational database containing personal records, while ensuring individual privacy and maintaining data integrity to the extent possible. One of the techniques proposed in the literature is k-anonymization. A release is considered k-anonymous if the information for each person contained in the release cannot be distinguished from at least k–1 other persons whose information also appears in the release. In the k-Anonymityproblem the objective is to minimally suppress cells in the table so as to ensure that the released version is k-anonymous. We show that the k-Anonymity problem is NP-hard even when the attribute values are ternary. On the positive side, we provide an O(k)-approximation algorithm for the problem. This improves upon the previous best-known O(klog k)-approximation. We also give improved positive results for the interesting cases with specific values of k — in particular, we give a 1.5-approximation algorithm for the special case of 2-Anonymity, and a 2-approximation algorithm for 3-Anonymity.