Distance-Aware Private Set Intersection

TL;DR

This paper introduces distance-aware private set intersection (DA-PSI), enabling two parties to find pairs of items within a certain distance in a metric space, with efficient protocols for Minkowski and Hamming distances, validated by real-world experiments.

Contribution

The paper presents the first DA-PSI protocols for Minkowski and Hamming distances, optimizing communication complexity based on distance thresholds.

Findings

DA-PSI protocols are more effective and cost-efficient than naive solutions.

Communication complexity scales favorably with distance thresholds.

Experimental results validate practical efficiency and accuracy.

Abstract

Private set intersection (PSI) allows two mutually untrusting parties to compute an intersection of their sets, without revealing information about items that are not in the intersection. This work introduces a PSI variant called distance-aware PSI (DA-PSI) for sets whose elements lie in a metric space. DA-PSI returns pairs of items that are within a specified distance threshold of each other. This paper puts forward DA-PSI constructions for two metric spaces: (i) Minkowski distance of order 1 over the set of integers (i.e., for integers $a$ and $b$, their distance is $|a-b|$); and (ii) Hamming distance over the set of binary strings of length $\ell$. In the Minkowski DA-PSI protocol, the communication complexity scales logarithmically in the distance threshold and linearly in the set size. In the Hamming DA-PSI protocol, the communication volume scales quadratically in the distance threshold and is independent of the dimensionality of string length $\ell$. Experimental results with real applications confirm that DA-PSI provides more effective matching at lower cost than naive solutions.