Total Protection of Analytic Invariant Information in Cross Tabulated Tables

TL;DR

This paper introduces algorithms to detect and prevent the leakage of sensitive information in cross tabulated tables by analyzing analytic invariants and optimizing cell suppression strategies.

Contribution

It provides an optimal linear-time algorithm for detecting analytic invariants and an NP-completeness result with an efficient approximation algorithm for suppressing minimal cells.

Findings

Linear-time algorithm for invariant detection

NP-completeness of minimal suppression problem

Approximate algorithm for cell suppression

Abstract

To protect sensitive information in a cross tabulated table, it is a common practice to suppress some of the cells in the table. An analytic invariant is a power series in terms of the suppressed cells that has a unique feasible value and a convergence radius equal to +\infty. Intuitively, the information contained in an invariant is not protected even though the values of the suppressed cells are not disclosed. This paper gives an optimal linear-time algorithm for testing whether there exist nontrivial analytic invariants in terms of the suppressed cells in a given set of suppressed cells. This paper also presents NP-completeness results and an almost linear-time algorithm for the problem of suppressing the minimum number of cells in addition to the sensitive ones so that the resulting table does not leak analytic invariant information about a given set of suppressed cells.