LLMDet: A Large Language Models Detection Tool

With the advancement of generative language models, the generated text has come remarkably close to high-quality human-authored text in terms of fluency and diversity. This calls for a highly practical detection tool that can identify the source of text, preferably pinpointing the language model it originates from. However, existing detection tools typically require access to language models and can only differentiate between machine-generated and human-authored text, failing to meet the requirements of rapid detection and text tracing. Therefore, in this paper, we propose an efficient, secure, and scalable detection tool called LLMDet, which calculates the proxy perplexity of text by utilizing the prior information of the model's next-token probabilities, obtained through pre-training. Subsequently, we use the self-watermarking information of the model, as measured by proxy perplexity, to detect the source of the text. We found that our method demonstrates impressive detection performance while ensuring speed and security, particularly achieving a recognition accuracy of 97.97\% for human-authored text. Furthermore, our detection tool also shows promising results in identifying the large language model (e.g., GPT-2, OPT, LLaMA, Vicuna...) responsible for the text. We release the code and processed data at \url{https://github.com/TrustedLLM/LLMDet}.