A novel analysis of utility in privacy pipelines, using Kronecker products and quantitative information flow
Mário S. Alvim, Natasha Fernandes, Annabelle McIver, Carroll Morgan, Gabriel H. Nunes
TL;DR
This work combines Kronecker products, and quantitative information flow, to give a novel formal analysis for the fine-grained verification of utility in complex privacy pipelines, and offers the prospect of formal-analysis tools for utility that complement extant formal analyses of privacy.
Abstract
We combine Kronecker products, and quantitative information flow, to give a novel formal analysis for the fine-grained verification of utility in complex privacy pipelines. The combination explains a surprising anomaly in the behaviour of utility of privacy-preserving pipelines -- that sometimes a reduction in privacy results also in a decrease in utility. We use the standard measure of utility for Bayesian analysis, introduced by Ghosh at al., to produce tractable and rigorous proofs of the fine-grained statistical behaviour leading to the anomaly. More generally, we offer the prospect of formal-analysis tools for utility that complement extant formal analyses of privacy. We demonstrate our results on a number of common privacy-preserving designs.