K-anonymity

k-anonymity is a property possessed by certain anonymized data. The term k-anonymity was first introduced by Pierangela Samarati and Latanya Sweeney in a paper published in 1998, although the concept dates to a 1986 paper by Tore Dalenius. k-anonymity is an attempt to solve the problem "Given person-specific field-structured data, produce a release of the data with scientific guarantees that the individuals who are the subjects of the data cannot be re-identified while the data remain practically useful." A release of data is said to have the k-anonymity property if the information for each person contained in the release cannot be distinguished from at least individuals whose information also appear in the release. Unfortunately, the guarantees provided by k-anonymity are aspirational, not mathematical. To use k-anonymity to process a dataset so that it can be released with privacy protection, a data scientist must first examine the dataset and decide whether each attribute (column) is an identifier (identifying), a non-identifier (not-identifying), or a quasi-identifier (somewhat identifying). Identifiers such as names are suppressed, non-identifying values are allowed to remain, and the quasi-identifiers need to be processed so that every distinct combination of quasi-identifiers designates at least k records. In the example table below presents a fictional nonanonymized database consisting of the patient records for a fictitious hospital. The Name column is an identifier, Age, Gender, State of domicile, and Religion are quasi-identifiers, and Disease is a non-identifying sensitive value. But what about Height and Weight? Are they also non-identifying sensitive values, or are they quasi-identifiers? There are 6 attributes and 10 records in this data. There are two common methods for achieving k-anonymity for some value of k: Suppression. In this method, certain values of the attributes are replaced by an asterisk "". All or some values of a column may be replaced by "".