ML Model Confidence Swapping to Block Extraction

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Solution Overview

Problem

Machine learning models are vulnerable to model extraction attacks, where an attacker can create a near-identical copy of the model by using valid queries and outputs, leading to potential misuse and additional attacks.

Innovation Solution

The method involves randomly swapping the confidence levels of prediction results for input samples deemed as attacks, making it difficult for attackers to duplicate the model by comparing the distribution of normal and adversarial input samples and using a private key for generating randomness in the swapping process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the machine learning model provides accurate confidence levels for prediction results, then the model's reliability is improved, but the model becomes vulnerable to extraction attacks

Engineering Contradiction:
Improveprediction accuracyVSAvoidextraction attack vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system preemptively detects attack patterns by comparing input distributions before extraction can occur. When an attack is detected, confidence levels are deliberately corrupted to prevent the attacker from gathering accurate information needed for model extraction, thus neutralizing the threat before it can compromise model security.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The system applies different quality standards to different users: legitimate users receive accurate confidence levels for reliable predictions, while attackers receive corrupted confidence levels that prevent extraction. This localized differentiation of information quality protects against attacks without degrading service for legitimate users.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the model outputs correct prediction results for all queries, then user satisfaction is improved, but attackers can easily duplicate the model

Engineering Contradiction:
Improveuser satisfactionVSAvoidmodel security
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The system introduces an intermediary detection layer that sits between the model and users. This intermediary analyzes input patterns to distinguish legitimate users from attackers, then selectively applies confidence level corruption only to attack queries. Legitimate users continue to receive accurate results while attackers receive corrupted information, thus protecting model security without affecting user satisfaction.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the system implements attack detection and confidence level swapping, then model protection is improved, but system complexity increases

Engineering Contradiction:
Improveattack resistanceVSAvoidsystem architecture
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system protects the model by changing the parameter being returned (confidence level) rather than modifying the core model architecture. When an attack is detected, the system swaps confidence level values between prediction results, which is a simple parameter manipulation that provides strong protection without requiring complex structural changes to the model or system.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11100222B2Method for hardening a machine learning model against extraction
Publication Date: 2021.08.24 NXP BV
  • US11100222B2 patent drawing
  • US11100222B2 patent drawing
  • US11100222B2 patent drawing

AI summary

A method is provided for protecting a trained machine learning model that provides prediction results with confidence levels. The confidence level is a measure of the likelihood that a prediction is correct. The method includes determining if a query input to the model is an attempted attack on the model. If the query is determined to be an attempted attack, a first prediction result having a highest confidence level is swapped with a second prediction result having a relatively lower confidence level so that the first and second prediction results and confidence levels are re-paired. Then, the second prediction result is output from the model with the highest confidence level. By swapping the confidence levels and outputting the prediction results with the swapped confidence levels, the machine learning model is more difficult for an attacker to extract.