LLMDet: A Third Party Large Language Models Generated Text Detection Tool

TL;DR

LLMDet is a practical, fast, and extendable detection tool that accurately identifies the specific large language model source of generated texts, addressing limitations of existing methods.

Contribution

The paper introduces LLMDet, a novel detection tool that can source texts from specific LLMs with high accuracy, speed, and extendability, surpassing existing tools.

Findings

Achieves 98.54% precision in detection

Operates 5 times faster than previous methods

Easily extendable to new open-source models

Abstract

Generated texts from large language models (LLMs) are remarkably close to high-quality human-authored text, raising concerns about their potential misuse in spreading false information and academic misconduct. Consequently, there is an urgent need for a highly practical detection tool capable of accurately identifying the source of a given text. However, existing detection tools typically rely on access to LLMs and can only differentiate between machine-generated and human-authored text, failing to meet the requirements of fine-grained tracing, intermediary judgment, and rapid detection. Therefore, we propose LLMDet, a model-specific, secure, efficient, and extendable detection tool, that can source text from specific LLMs, such as GPT-2, OPT, LLaMA, and others. In LLMDet, we record the next-token probabilities of salient n-grams as features to calculate proxy perplexity for each LLM. By jointly analyzing the proxy perplexities of LLMs, we can determine the source of the generated text. Experimental results show that LLMDet yields impressive detection performance while ensuring speed and security, achieving 98.54% precision and x5.0 faster for recognizing human-authored text. Additionally, LLMDet can effortlessly extend its detection capabilities to a new open-source model. We will provide an open-source tool at https://github.com/TrustedLLM/LLMDet.