Masked Language Modeling for Adversarial Prompt Detection
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Solution Overview
Problem
Adversarial attacks on natural language processing (NLP) models, which involve small perturbations causing misclassification or manipulation of model outputs, are not effectively addressed by existing methods, particularly those requiring specific model training or tuning.
Innovation Solution
A masked language modeling approach using a pretrained MLM model to detect adversarial attacks by tokenizing input sentences, calculating suspicion levels for each token, and applying Gaussian weighting to identify suspicious tokens, without requiring specific model training.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing defense methods are used against adversarial attacks, then model protection is attempted, but computational cost increases and model-specific training is required
Solution Approach 1:
The MLM model detects adversarial attacks by analyzing the input text itself through mask token substitution and probability calculation, without requiring external defense models or additional training. The system uses its own language modeling capabilities to identify suspicious tokens, making the defense mechanism self-contained and computationally efficient.
Solution Approach 2:
The defense mechanism is model-agnostic and can be applied to any NLP model that uses tokenization. By using a pretrained MLM model that works with general language structures, the system provides universal protection across different NLP architectures without requiring model-specific training or customization.
2Measurement precision
If model-specific training is used for defense, then detection accuracy may improve, but adaptability to different NLP models decreases
Solution Approach 1:
The defense mechanism is model-agnostic and can be applied to any NLP model that uses tokenization. By using a pretrained MLM model that works with general language structures, the system provides universal protection across different NLP architectures without requiring model-specific training or customization.
Solution Approach 2:
The MLM model acts as an intermediary layer between the input text and the target NLP model. It analyzes the input text independently through mask token substitution and suspicion level calculation, then provides defense decisions without being tied to the specific architecture or training of the target model, thus maintaining both accuracy and adaptability.
3Measurement precision
If comprehensive token analysis is performed, then attack detection accuracy improves, but computational complexity increases
Solution Approach 1:
The system segments the attack detection process into discrete steps: tokenizing the input text, substituting each token with a mask token, calculating suspicion levels for each position, and identifying adversarial tokens. This segmentation allows for systematic analysis while maintaining computational efficiency through modular processing.
Solution Approach 2:
The system performs suspicion level calculation for each token position in the text, which may be more computation than strictly necessary. However, this excessive action ensures comprehensive coverage and high detection accuracy by analyzing every possible attack insertion point, with the trade-off managed through efficient use of pretrained MLM probabilities.
Data Source
AI summary
One example method includes receiving a text string that includes multiple words, tokenizing the text string to create a tokenized text string, substituting each token in the tokenized text string with a mask token to create a masked text string, performing an inference process on the masked text string to obtain a respective probability for each token, determining a respective suspicion level for each probability, modulating the suspicion levels to obtain a respective weighted suspicion score for each token, and comparing each of the weighted suspicion scores with a threshold to determine whether any one or more of the words indicate that the text string includes an attack prompt.


