Robustness Assessment and Enhancement of Text Watermarking for Google's SynthID

Fuente: arXiv
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Main Authors: Han, Xia, Li, Qi, Ni, Jianbing, Zulkernine, Mohammad
Format: Preprint
Published: 2025
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author Han, Xia
Li, Qi
Ni, Jianbing
Zulkernine, Mohammad
author_facet Han, Xia
Li, Qi
Ni, Jianbing
Zulkernine, Mohammad
contents Recent advances in LLM watermarking methods such as SynthID-Text by Google DeepMind offer promising solutions for tracing the provenance of AI-generated text. However, our robustness assessment reveals that SynthID-Text is vulnerable to meaning-preserving attacks, such as paraphrasing, copy-paste modifications, and back-translation, which can significantly degrade watermark detectability. To address these limitations, we propose SynGuard, a hybrid framework that combines the semantic alignment strength of Semantic Information Retrieval (SIR) with the probabilistic watermarking mechanism of SynthID-Text. Our approach jointly embeds watermarks at both lexical and semantic levels, enabling robust provenance tracking while preserving the original meaning. Experimental results across multiple attack scenarios show that SynGuard improves watermark recovery by an average of 11.1\% in F1 score compared to SynthID-Text. These findings demonstrate the effectiveness of semantic-aware watermarking in resisting real-world tampering. All code, datasets, and evaluation scripts are publicly available at: https://github.com/githshine/SynGuard.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20228
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Robustness Assessment and Enhancement of Text Watermarking for Google's SynthID
Han, Xia
Li, Qi
Ni, Jianbing
Zulkernine, Mohammad
Cryptography and Security
Computation and Language
Recent advances in LLM watermarking methods such as SynthID-Text by Google DeepMind offer promising solutions for tracing the provenance of AI-generated text. However, our robustness assessment reveals that SynthID-Text is vulnerable to meaning-preserving attacks, such as paraphrasing, copy-paste modifications, and back-translation, which can significantly degrade watermark detectability. To address these limitations, we propose SynGuard, a hybrid framework that combines the semantic alignment strength of Semantic Information Retrieval (SIR) with the probabilistic watermarking mechanism of SynthID-Text. Our approach jointly embeds watermarks at both lexical and semantic levels, enabling robust provenance tracking while preserving the original meaning. Experimental results across multiple attack scenarios show that SynGuard improves watermark recovery by an average of 11.1\% in F1 score compared to SynthID-Text. These findings demonstrate the effectiveness of semantic-aware watermarking in resisting real-world tampering. All code, datasets, and evaluation scripts are publicly available at: https://github.com/githshine/SynGuard.
title Robustness Assessment and Enhancement of Text Watermarking for Google's SynthID
topic Cryptography and Security
Computation and Language
url https://arxiv.org/abs/2508.20228