Secure Aggregation for Malicious Client Identification

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Solution Overview

Problem

Existing methods for secure aggregation in federated machine learning face a compromise between data privacy, resilience to malicious users, and efficiency, as they struggle to effectively identify and exclude malicious clients while maintaining user data privacy.

Innovation Solution

The method involves grouping clients into partially overlapping client groups, estimating malicious clients using quality metrics and decoding algorithms, and determining a benign data aggregate by excluding malicious clients, thereby isolating their contributions and improving the resilience of the aggregation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If clients share local gradients for model updates in federated learning, then the global model can be trained collaboratively, but significant information about client data may be leaked

Engineering Contradiction:
Improvecollaborative model training efficiencyVSAvoidclient data privacy
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent introduces secure aggregation protocols as an intermediary mechanism that processes client gradients through masked contributions and secret sharing. The server receives encrypted gradient updates from clients, aggregates them without accessing individual client data, and updates the global model. This intermediary layer ensures that while collaborative training proceeds efficiently, client data privacy is preserved through cryptographic masking and secret sharing techniques.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of information

If secure aggregation protocols are implemented to protect client privacy, then data privacy is improved, but the system becomes more vulnerable to malicious users

Engineering Contradiction:
Improveclient data privacyVSAvoidresilience to malicious attacks
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent implements preliminary detection mechanisms that identify malicious clients before their attacks can compromise the secure aggregation process. The system uses anomaly detection algorithms to analyze client behavior patterns, gradient update characteristics, and participation metrics in advance. Malicious clients are flagged and excluded from the aggregation process before they can inject harmful updates, thereby protecting both privacy and reliability simultaneously.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If malicious clients are detected and excluded from aggregation, then resilience to attacks is improved, but the complexity of the aggregation process increases

Engineering Contradiction:
Improveresilience to malicious attacksVSAvoidaggregation process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the aggregation process into distinct modular stages: client authentication, gradient computation, anomaly detection, secure masking, aggregation, and model updating. Each stage is independently processed and can be implemented as separate computational modules. This segmentation reduces overall system complexity by breaking down the complex aggregation process into manageable, standardized operations that can be efficiently executed and monitored.

Inventive Principle:
Principle #1Segmentation

4Reliability

If standard deviation thresholds are used to detect suspicious subgroups, then malicious user impact can be reduced, but the detection accuracy may compromise benign clients

Engineering Contradiction:
Improvemalicious user detectionVSAvoidclient classification accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent dynamically adjusts detection parameters including standard deviation thresholds, confidence levels, and anomaly sensitivity based on the specific federated learning context, data distribution characteristics, and observed attack patterns. The system continuously learns optimal parameter values through feedback from detection outcomes and adjusts them accordingly. This adaptive parameter tuning enables accurate differentiation between malicious and benign clients while minimizing false positives and maintaining high detection precision.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4446920A1A method and system for identification of malicious clients with secure aggregation of data from a plurality of clients
Publication Date: 2024.10.16 TECHNISCHE UNIVERSITAET MUENCHEN INVERTRETUNG DES FREISTAATES BAYERN
  • EP4446920A1 patent drawingFigure 1
  • EP4446920A1 patent drawingFigure 2
  • EP4446920A1 patent drawingFigure 3

AI summary

A computer-implemented method for secure aggregation of data from a plurality of clients. The method comprises requesting data from the plurality of clients , and receiving a plurality of masked data portions from the plurality of clients , wherein the plurality of clients are grouped into a plurality of partially overlapping client groups , and each masked data portion is associated with one of the client groups. The method further comprises aggregating the masked data portions of each client group to obtain a plurality of group data aggregates, wherein each group data aggregate is associated with a respective client group , and estimating, based on a quality metric for each of the plurality of group data aggregates, a subset of malicious clients of the plurality of clients. The method further comprises determining a benign data aggregate based on a remaining plurality of benign clients, wherein the benign clients do not form part of the malicious clients.