CATMark: A Context-Aware Thresholding Framework for Robust Cross-Task Watermarking in Large Language Models

YU Zhang, Shuliang Liu, Yang Xu, Xuming Hu


Abstract
Watermarking algorithms for Large Language Models (LLMs) effectively identify machine-generated content by embedding and detecting hidden statistical features in text. However, such embedding leads to a decline in text quality, especially in low-entropy scenarios where performance needs improvement. Existing methods that rely on entropy thresholds often require significant computational resources for tuning and demonstrate poor adaptability to unknown or cross-task generation scenarios. We propose Context-Aware Threshold watermarking (CATMark), a novel framework that dynamically adjusts watermarking intensity based on real-time semantic context. CATMark partitions text generation into semantic states using logits clustering, establishing context-aware entropy thresholds that preserve fidelity in structured content while embedding robust watermarks. Crucially, it requires no pre-defined thresholds or task-specific tuning. Experiments show CATMark improves text quality in cross-tasks without sacrificing detection accuracy.
Anthology ID:
2026.emnlp-main.375
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
8571–8600
Language:
URL:
https://aclanthology.org/2026.emnlp-main.375/
DOI:
Bibkey:
Cite (ACL):
YU Zhang, Shuliang Liu, Yang Xu, and Xuming Hu. 2026. CATMark: A Context-Aware Thresholding Framework for Robust Cross-Task Watermarking in Large Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 8571–8600, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CATMark: A Context-Aware Thresholding Framework for Robust Cross-Task Watermarking in Large Language Models (Zhang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.375.pdf