Attribute disclosure risk for k-anonymity: the case of numerical data

Abstract

k-Anonymity is one of the most well-known privacy models. Internal and external attacks were discussed for this privacy model, both focusing on categorical data. These attacks can be seen as attribute disclosure for a particular attribute. Then, p-sensitivity and p-diversity were proposed as solutions for these privacy models. That is, as a way to avoid attribute disclosure for this very attribute. In this paper we discuss the case of numerical data, and we show that attribute disclosure can also take place. For this, we use well-known rules to detect sensitive cells in tabular data protection. Our experiments show that k-anonymity is not immune to attribute disclosure in this sense. We have analyzed the results of two different algorithms for achieving k-anonymity. First, MDAV as a way to provide microaggregation and k-anonymity. Second, Mondrian. In fact, to our surprise, the number of cells detected as sensitive is quite significant, and there are no fundamental differences between Mondrian and MDAV. We describe the experiments considered, and the results obtained. We define dominance rule compliant and p%-rule compliant k-anonymity for k-anonymity taking into account attribute disclosure. We conclude with an analysis and directions for future research.