Encode-Shuffle Analyze Framework for Private Frequency Moment Estimation

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Solution Overview

Problem

Current differential privacy methods face challenges in effectively estimating frequency moments and low-rank approximations while maintaining user data privacy, especially in large-scale crowdsourced data environments, where existing techniques lack accuracy and practicality.

Innovation Solution

The implementation of the encode-shuffle then analyze (ESA) framework, which uses a local randomizer on client devices to generate a randomized sketch based on a p-stable distribution matrix, allowing for differential privacy in estimating frequency moments and low-rank approximations through a non-private estimator, while reducing data size and maintaining privacy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If local differential privacy is applied to protect user data in crowdsourced environments, then privacy protection is improved, but measurement precision of frequency moments deteriorates

Engineering Contradiction:
Improveprivacy protectionVSAvoidfrequency moment estimation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent transforms the data representation by generating sketches in a lower-dimensional space while preserving statistical properties. Instead of directly privatizing high-dimensional frequency data, the system projects data into a compressed sketch space using random projection matrices, then applies differential privacy. This dimensional transformation allows frequency moment estimation to maintain accuracy while achieving privacy guarantees.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces randomized sketches as an intermediary between the original data and the frequency moment estimation. These sketches serve as a mediating structure that preserves the essential statistical properties needed for accurate frequency moment calculation while being amenable to differential privacy protection. The sketches act as a bridge that maintains measurement precision through their design.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If data size is reduced through sketching for efficient processing, then productivity is improved, but loss of information increases

Engineering Contradiction:
Improvedata processing efficiencyVSAvoiddata detail retention
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent changes the parameters of data representation by transforming the full dataset into a sketch with controlled dimensions. The sketch size and projection matrix parameters are carefully selected to maintain the statistical properties necessary for frequency moment estimation. This parameter optimization ensures that processing efficiency gains from reduced data size do not come at the cost of essential information loss.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If shuffle model is used to enhance privacy in centralized data collection, then privacy protection is improved, but device complexity increases

Engineering Contradiction:
Improvedifferential privacy guaranteeVSAvoidsystem implementation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the differential privacy mechanism into distinct modular components: (1) sketch generation using random projection, (2) shuffle-based privatization, and (3) frequency moment estimation. This segmentation allows each component to be implemented and optimized independently, reducing overall system complexity while maintaining strong privacy guarantees through the combined effect of these modular elements.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11616765B2Practical private algorithms for robust statistics
Publication Date: 2023.03.28 APPLE INC
  • US11616765B2 patent drawing
  • US11616765B2 patent drawing
  • US11616765B2 patent drawing

AI summary

Embodiments described herein provide a privacy mechanism to protect user data when transmitting the data to a server that estimates a p-th frequency moment, Fp for p∈[1, 2] and p low-rank approximation for p∈[1, 2). The privacy mechanism uses an encode-shuffle then analyze (ESA) framework that provides a compromise between the central and local model of privacy.