An Effective and Differentially Private Protocol for Secure Distributed Cardinality Estimation

TL;DR

This paper introduces DP-DICE, a novel, efficient, and differentially private protocol for distributed cardinality estimation that outperforms existing methods in speed and accuracy while ensuring privacy.

Contribution

We propose DP-DICE, a new protocol that provides differential privacy and computational efficiency for distributed cardinality estimation, improving over prior MPC-based approaches.

Findings

DP-DICE achieves significant speedup over existing methods.

It reduces estimation error by several times.

The protocol maintains strong privacy guarantees.

Abstract

Counting the number of distinct elements distributed over multiple data holders is a fundamental problem with many real-world applications ranging from crowd counting to network monitoring. Although a number of space and computational efficient sketch methods (e.g., the Flajolet-Martin sketch and the HyperLogLog sketch) for cardinality estimation have been proposed to solve the above problem, these sketch methods are insecure when considering privacy concerns related to the use of each data holder's personal dataset. Despite a recently proposed protocol that successfully implements the well-known Flajolet-Martin (FM) sketch on a secret-sharing based multiparty computation (MPC) framework for solving the problem of private distributed cardinality estimation (PDCE), we observe that this MPC-FM protocol is not differentially private. In addition, the MPC-FM protocol is computationally expensive, which limits its applications to data holders with limited computation resources. To address the above issues, in this paper we propose a novel protocol DP-DICE, which is computationally efficient and differentially private for solving the problem of PDCE. Experimental results show that our DP-DICE achieves orders of magnitude speedup and reduces the estimation error by several times in comparison with state-of-the-arts under the same security requirements.