Federated Learning Model Privacy and Accuracy Trade-off

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Solution Overview

Problem

Federated learning in personal authentication faces challenges with data imbalance across clients, leading to decreased accuracy and privacy concerns due to the sharing of representative vectors.

Innovation Solution

A machine learning system where a server holds a common model, and clients hold concealment target data and individual models, with the server transmitting the common model to clients for updating based on local data, while protecting privacy through concealment transformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If federated learning is applied to personal authentication, then privacy of personal data is protected, but accuracy decreases when data is imbalanced in each client

Engineering Contradiction:
Improveprivacy protectionVSAvoidauthentication accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent divides the training data into multiple clients, each holding data from a single individual. This segmentation enables federated learning where each client trains locally on its own data without sharing personal information, thus protecting privacy while contributing to the global model. The model is segmented into local individual models and a global common model that aggregates knowledge from all clients.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a server as an intermediary that coordinates the federated learning process. The server aggregates local models from individual clients to create an updated common model, which is then distributed back to clients. This intermediary structure enables privacy protection by preventing direct data sharing while maintaining authentication accuracy through coordinated model aggregation and updates.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If only personal data on one person is stored in one client, then privacy is protected, but comparison with other classes cannot be made in the learning

Engineering Contradiction:
Improveprivacy protectionVSAvoidclassification accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent creates a common model that serves multiple functions: it acts as an individual model for each client while simultaneously serving as a universal model for all clients. This common model is trained on data from multiple individuals through federated learning, enabling it to perform class comparison and authentication across different individuals without requiring direct access to their personal data.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges local individual models from multiple clients into a single common model through the federated learning process. Each client contributes its local knowledge to the global model, which combines these diverse data sources while maintaining privacy. The merged common model achieves accurate classification by learning from the combined distribution of data across all clients.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If representative vectors are shared between client and server, then authentication accuracy is improved, but risk of impersonation and data leakage increases

Engineering Contradiction:
Improveauthentication accuracyVSAvoidimpersonation risk
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the traditional approach by having the server hold the common model instead of clients holding representative vectors. The server uses the common model to generate individual models for each client, which are then stored locally. This inversion improves security because the sensitive common model remains on the server, while clients only possess their individual models that are less informative for impersonation attacks.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the sensitive representative vectors from the clients and consolidates them into a common model on the server. This extraction removes the security vulnerability where clients would otherwise store and potentially leak their individual representative vectors. The server securely manages the aggregated model, reducing the attack surface for impersonation while maintaining authentication accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentUS20250068971A1Machine learning system and machine learning method
Publication Date: 2025.02.27 HITACHI LTD
  • US20250068971A1 patent drawing
  • US20250068971A1 patent drawing
  • US20250068971A1 patent drawing

AI summary

A machine learning system includes: a server holding a common model; and a plurality of clients each holding concealment target data and an individual model, the server transmits the common model to the plurality of clients, each of the plurality of clients: generates a learning result obtained by updating the common model based on the concealment target data and the individual model held by itself; and transmits the generated learning result to the server, and the server updates the common model based on the received learning result.