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

Kangxi Wu, Liang Pang, Huawei Shen, Xueqi Cheng, Tat-Seng Chua

Submission Type: Regular Long Paper

Submission Track: Theme Track: Large Language Models and the Future of NLP

Submission Track 2: NLP Applications

Keywords: Text Detection, Large Language Model, Fine-grained Tracing, Proxy Perplexity

TL;DR: We propose LLMDet, a model-specific, secure, efficient, and extendable detection tool for Large Language Models Generated Text, which can determine the source of the generated text.

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 about $\times 5.0$ 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 \url{https://github.com/TrustedLLM/LLMDet}.

Submission Number: 5411