Regression Tree Training with Fully Homomorphic Encryption

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Solution Overview

Problem

Existing machine learning model training methods face challenges in ensuring data privacy, particularly in heavily regulated industries like healthcare and finance, where outsourcing model training or sharing data with multiple parties raises privacy concerns.

Innovation Solution

The development of a privacy-preserving, non-interactive cryptographic protocol for training and inference on regression trees using fully homomorphic encryption (FHE), which allows computations on encrypted data without revealing sensitive information, along with efficient batching options and computational optimizations to enhance training throughput and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If data is shared for model training, then model accuracy is improved, but data privacy is compromised

Engineering Contradiction:
Improvemodel accuracyVSAvoiddata privacy
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

A trusted third party cryptographic system serves as an intermediary between data owners and model trainers. The system uses homomorphic encryption to enable computations on encrypted data, allowing the model to be trained on sensitive data without exposing the actual data values. The cryptographic protocol acts as a mediator that preserves data privacy while enabling accurate model training.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of information

If a trusted third party is used for secure training, then data privacy is protected, but system complexity and cost increase

Engineering Contradiction:
Improvedata privacyVSAvoidsystem complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The cryptographic system enables data owners to independently encrypt their data and perform verification without requiring a continuously active trusted third party. The system uses self-verifying cryptographic proofs that allow parties to autonomously verify the integrity and privacy of the training process, reducing reliance on complex intermediary infrastructure.

Inventive Principle:
Principle #25Self-service

3Loss of information

If traditional encryption methods are used, then data privacy is maintained, but computational efficiency deteriorates

Engineering Contradiction:
Improvedata privacyVSAvoidcomputational efficiency
Core Design Contradiction:
Loss of informationVSProductivity

Solution Approach 1:

Data is encrypted using homomorphic encryption schemes before being sent to the training environment. The encryption is performed in advance, allowing the model training to proceed on encrypted data without requiring real-time decryption. This preliminary encryption action enables efficient computation while maintaining privacy, as the heavy cryptographic operations are performed beforehand rather than during the training process.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20250192979A1Training optimization of regression trees using fully homomorphic encryption
Publication Date: 2025.06.12 SAP SE
  • US20250192979A1 patent drawing
  • US20250192979A1 patent drawing
  • US20250192979A1 patent drawing

AI summary

A computer implemented method can receive n training samples including sample values corresponding to m attributes and respective target values (n and m are positive integers), duplicate the sample values corresponding to the m attributes, pack the sample values into ciphertexts based on a batching option, and train a regression tree using the ciphertexts. The training is configured to encrypt the regression tree through homomorphic operations on the ciphertexts.