/*
* ARX: Powerful Data Anonymization
* Copyright 2012 - 2017 Fabian Prasser, Florian Kohlmayer and contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.deidentifier.arx.criteria;
import org.deidentifier.arx.ARXConfiguration;
import org.deidentifier.arx.certificate.elements.ElementData;
import org.deidentifier.arx.framework.check.groupify.HashGroupifyEntry;
import org.deidentifier.arx.framework.data.DataManager;
import org.deidentifier.arx.framework.lattice.Transformation;
/**
* Enhanced-beta-Likeness:<br>
* <br>
* Jianneng Cao, Panagiotis Karras:<br>
* Publishing Microdata with a Robust Privacy Guarantee<br>
* VLDB 2012.
*
* @author Fabian Prasser
*/
public class EnhancedBLikeness extends ExplicitPrivacyCriterion {
/** SVUID*/
private static final long serialVersionUID = 5319052409590347904L;
/** Parameter */
private final double b;
/** The original distribution. */
private double[] distribution;
/**
* Creates a new instance
*
* @param attribute
* @param beta
*/
public EnhancedBLikeness(String attribute, double beta) {
super(attribute, false, true);
if (beta <= 0) {
throw new IllegalArgumentException("Beta (" + beta + ") must be > 0");
}
this.b = beta;
}
@Override
public EnhancedBLikeness clone() {
return new EnhancedBLikeness(this.getAttribute(), this.getB());
}
/**
* Returns the parameter beta.
*
* @return
*/
public double getB(){
return this.b;
}
@Override
public int getRequirements(){
// Requires a distribution
return ARXConfiguration.REQUIREMENT_DISTRIBUTION;
}
@Override
public void initialize(DataManager manager, ARXConfiguration config) {
super.initialize(manager, config);
this.distribution = manager.getDistribution(attribute);
}
@Override
public boolean isAnonymous(Transformation node, HashGroupifyEntry entry) {
// For table t
// For each class c
// For each sensitive value s
// (freq(s, c) - freq(s, t)) / freq(s, t) <= min(beta, - ln(freq(s, t)))
// Init
int[] buckets = entry.distributions[index].getBuckets();
double count = entry.count;
// For each value in c
for (int i = 0; i < buckets.length; i += 2) {
if (buckets[i] != -1) { // bucket not empty
double frequencyInT = distribution[buckets[i]];
double frequencyInC = (double) buckets[i + 1] / count;
double value = (frequencyInC - frequencyInT) / frequencyInT;
if (value > Math.min(b, - Math.log(frequencyInT))) {
return false;
}
}
}
// check
return true;
}
@Override
public boolean isLocalRecodingSupported() {
return true;
}
@Override
public ElementData render() {
ElementData result = new ElementData("Enhanced likeness");
result.addProperty("Attribute", attribute);
result.addProperty("Threshold (beta)", b);
return result;
}
@Override
public String toString() {
return "enhanced-" + b + "-likeness for attribute '" + attribute + "'";
}
}