Prompt Classifier Training for Low False Positive AI Filtering
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Solution Overview
Problem
Existing binary classifiers, particularly in the context of malicious prompt classification for generative AI systems, struggle to maintain high true positive rates (TPR) at low false positive rates (FPR) thresholds, leading to missed malicious verdicts and high false positive classifications, as conventional metrics like area under the ROC curve are inadequate for high-volume classification scenarios.
Innovation Solution
A training methodology using a 'double cross-entropy loss function' combined with knowledge distillation (KD) loss to train a large and lightweight prompt classifiers, where the double cross-entropy loss penalizes specific misclassification types, and KD loss aligns the lightweight classifier with the large classifier's outputs, ensuring high TPR at low FPR thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high classification threshold is set to reduce false positive rate, then false positive rate decreases, but true positive rate also decreases resulting in missed malicious verdicts
Solution Approach 1:
The patent applies parameter changes by introducing a second loss function with adjustable weighting parameter alpha that balances false positive and false negative penalties. By tuning this parameter, the system can optimize the trade-off between TPR and FPR without being constrained by a fixed classification threshold, allowing flexible adaptation to different operational requirements.
Solution Approach 2:
The patent implements dynamics by making the loss function adaptive through the alpha parameter, which allows the classification system to dynamically adjust its behavior based on operational context. The system can shift between prioritizing false positive reduction and false negative reduction by changing the alpha value, rather than being locked into a static threshold-based approach.
2Productivity
If conventional cross-entropy loss function is used for training, then training is simple and fast, but the classifier cannot achieve high TPR at low FPR thresholds
Solution Approach 1:
The patent applies composite materials by combining the conventional cross-entropy loss function with a second custom loss function in a weighted sum. This composite loss function integrates the simplicity and speed of standard cross-entropy with the targeted false positive/false negative balancing capability of the custom loss term, achieving both training efficiency and improved classification performance.
Solution Approach 2:
The patent merges two loss functions - the standard cross-entropy loss and a custom loss function with false positive/false negative terms - into a unified training objective. This combination allows the system to benefit from both the computational efficiency of standard cross-entropy and the performance benefits of targeted error rate control.
Data Source
AI summary
A double cross-entropy loss function is a modification of the standard cross-entropy loss function that is tunable to penalize specific error types, i.e., false positives and false positives for binary classification. A prompt classifier is trained using the double cross-entropy loss function to classify prompts as malicious or benign. The double cross-entropy loss function for the prompt classifier is tuned so that false positive classifications are heavily penalized. The resulting trained prompt classifier maintains a high true positive rate while having a classification threshold that keeps the false positive rate very small. The trained prompt classifier is deployed in a high-load environment for prompt classification.


