Multibit Histogram Differential Privacy Encoding

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Solution Overview

Problem

Current differential privacy mechanisms face challenges in providing accurate frequency estimations while ensuring user data privacy, especially when dealing with large datasets, as they often introduce increased variance in accuracy to preserve privacy.

Innovation Solution

The implementation of differential privacy encoding techniques that involve encoding user data using vectors or Hadamard matrices, where bit values are updated or flipped with a predefined probability to create privatized vectors, allowing servers to estimate frequency without learning individual user data, thereby reducing resource requirements and providing provable privacy guarantees.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current differential privacy mechanisms are used to preserve user data privacy, then privacy protection is improved, but the accuracy of frequency estimations deteriorates due to increased variance

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

Solution Approach 1:

The patent segments the frequency estimation problem into multiple independent binomial trials. Instead of estimating frequency directly from aggregated data, the system divides the estimation into multiple discrete trials where each trial contributes to the overall estimate. This segmentation allows the use of statistical properties of binomial distributions to achieve both privacy and accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter representation from direct frequency values to probabilities of bit flips. By transforming the frequency estimation problem into a parameter estimation problem for binomial distributions, the system can leverage statistical inference techniques that provide both privacy guarantees through differential privacy and improved accuracy through efficient parameter estimation.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If more user information is gathered to improve pattern recognition and user experience, then utility is improved, but the difficulty of maintaining differential privacy increases

Engineering Contradiction:
Improveuser experience enhancementVSAvoiddifferential privacy mechanism complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential information needed for frequency estimation while discarding individual user data. By using local differential privacy at the client level, the system extracts aggregated frequency information without extracting or storing any individually identifiable user data, thus simplifying the privacy mechanism while maintaining utility.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements self-service differential privacy where each client device independently applies privacy-preserving transformations to its own data before transmission. This eliminates the need for complex centralized privacy mechanisms, as each client autonomously protects its data while contributing to the overall frequency estimation.

Inventive Principle:
Principle #25Self-service

3Reliability

If local differential privacy is applied to introduce randomness into user data, then privacy is improved, but the variance in accuracy of estimations worsens

Engineering Contradiction:
Improvedifferential privacy guaranteeVSAvoidestimation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses periodic action through multiple independent binomial trials. Instead of a single randomization step, the system performs multiple independent trials where privacy-preserving randomization is applied repeatedly. The aggregation of results from these periodic trials reduces variance through the law of large numbers while maintaining differential privacy guarantees.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent incorporates feedback through statistical inference from aggregated responses. The server uses the aggregated bit flip patterns as feedback to infer the underlying frequency distribution. This feedback mechanism allows the system to recover accurate frequency estimates from the noisy, privacy-preserving responses by leveraging the statistical structure of the aggregated data.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11501008B2Differential privacy using a multibit histogram
Publication Date: 2022.11.15 APPLE INC
  • US11501008B2 patent drawing
  • US11501008B2 patent drawing
  • US11501008B2 patent drawing

AI summary

Embodiments described herein ensure differential privacy when transmitting data to a server that estimates a frequency of such data amongst a set of client devices. The differential privacy mechanism may provide a predictable degree of variance for frequency estimations of data. The system may use a multibit histogram model or Hadamard multibit model for the differential privacy mechanism, both of which provide a predictable degree of accuracy of frequency estimations while still providing mathematically provable levels of privacy.