Enhancing LLM Watermark Resilience Against Both Scrubbing and Spoofing Attacks

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Hauptverfasser: Shen, Huanming, Huang, Baizhou, Wan, Xiaojun
Format: Preprint
Veröffentlicht: 2025
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author Shen, Huanming
Huang, Baizhou
Wan, Xiaojun
author_facet Shen, Huanming
Huang, Baizhou
Wan, Xiaojun
contents Watermarking is a promising defense against the misuse of large language models (LLMs), yet it remains vulnerable to scrubbing and spoofing attacks. This vulnerability stems from an inherent trade-off governed by watermark window size: smaller windows resist scrubbing better but are easier to reverse-engineer, enabling low-cost statistics-based spoofing attacks. This work breaks this trade-off by introducing a novel mechanism, equivalent texture keys, where multiple tokens within a watermark window can independently support the detection. Based on the redundancy, we propose a novel watermark scheme with Sub-vocabulary decomposed Equivalent tExture Key (SEEK). It achieves a Pareto improvement, increasing the resilience against scrubbing attacks without compromising robustness to spoofing. Experiments demonstrate SEEK's superiority over prior method, yielding spoofing robustness gains of +88.2%/+92.3%/+82.0% and scrubbing robustness gains of +10.2%/+6.4%/+24.6% across diverse dataset settings.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06274
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enhancing LLM Watermark Resilience Against Both Scrubbing and Spoofing Attacks
Shen, Huanming
Huang, Baizhou
Wan, Xiaojun
Cryptography and Security
Artificial Intelligence
Watermarking is a promising defense against the misuse of large language models (LLMs), yet it remains vulnerable to scrubbing and spoofing attacks. This vulnerability stems from an inherent trade-off governed by watermark window size: smaller windows resist scrubbing better but are easier to reverse-engineer, enabling low-cost statistics-based spoofing attacks. This work breaks this trade-off by introducing a novel mechanism, equivalent texture keys, where multiple tokens within a watermark window can independently support the detection. Based on the redundancy, we propose a novel watermark scheme with Sub-vocabulary decomposed Equivalent tExture Key (SEEK). It achieves a Pareto improvement, increasing the resilience against scrubbing attacks without compromising robustness to spoofing. Experiments demonstrate SEEK's superiority over prior method, yielding spoofing robustness gains of +88.2%/+92.3%/+82.0% and scrubbing robustness gains of +10.2%/+6.4%/+24.6% across diverse dataset settings.
title Enhancing LLM Watermark Resilience Against Both Scrubbing and Spoofing Attacks
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2507.06274