Linguistic Steganalysis via LLMs: Two Modes for Efficient Detection of Strongly Concealed Stego

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Hauptverfasser: Tang, Yifan, Wang, Yihao, Zhang, Ru, Liu, Jianyi
Format: Preprint
Veröffentlicht: 2024
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author Tang, Yifan
Wang, Yihao
Zhang, Ru
Liu, Jianyi
author_facet Tang, Yifan
Wang, Yihao
Zhang, Ru
Liu, Jianyi
contents To detect stego (steganographic text) in complex scenarios, linguistic steganalysis (LS) with various motivations has been proposed and achieved excellent performance. However, with the development of generative steganography, some stegos have strong concealment, especially after the emergence of LLMs-based steganography, the existing LS has low detection or cannot detect them. We designed a novel LS with two modes called LSGC. In the generation mode, we created an LS-task "description" and used the generation ability of LLM to explain whether texts to be detected are stegos. On this basis, we rethought the principle of LS and LLMs, and proposed the classification mode. In this mode, LSGC deleted the LS-task "description" and used the "causalLM" LLMs to extract steganographic features. The LS features can be extracted by only one pass of the model, and a linear layer with initialization weights is added to obtain the classification probability. Experiments on strongly concealed stegos show that LSGC significantly improves detection and reaches SOTA performance. Additionally, LSGC in classification mode greatly reduces training time while maintaining high performance.
format Preprint
id arxiv_https___arxiv_org_abs_2406_04218
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Linguistic Steganalysis via LLMs: Two Modes for Efficient Detection of Strongly Concealed Stego
Tang, Yifan
Wang, Yihao
Zhang, Ru
Liu, Jianyi
Computation and Language
To detect stego (steganographic text) in complex scenarios, linguistic steganalysis (LS) with various motivations has been proposed and achieved excellent performance. However, with the development of generative steganography, some stegos have strong concealment, especially after the emergence of LLMs-based steganography, the existing LS has low detection or cannot detect them. We designed a novel LS with two modes called LSGC. In the generation mode, we created an LS-task "description" and used the generation ability of LLM to explain whether texts to be detected are stegos. On this basis, we rethought the principle of LS and LLMs, and proposed the classification mode. In this mode, LSGC deleted the LS-task "description" and used the "causalLM" LLMs to extract steganographic features. The LS features can be extracted by only one pass of the model, and a linear layer with initialization weights is added to obtain the classification probability. Experiments on strongly concealed stegos show that LSGC significantly improves detection and reaches SOTA performance. Additionally, LSGC in classification mode greatly reduces training time while maintaining high performance.
title Linguistic Steganalysis via LLMs: Two Modes for Efficient Detection of Strongly Concealed Stego
topic Computation and Language
url https://arxiv.org/abs/2406.04218