Class-feature Watermark: A Resilient Black-box Watermark Against Model Extraction Attacks

Fuente: arXiv
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Main Authors: Xiao, Yaxin, Ye, Qingqing, Liang, Zi, Li, Haoyang, Li, RongHua, Zheng, Huadi, Hu, Haibo
Format: Preprint
Published: 2025
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author Xiao, Yaxin
Ye, Qingqing
Liang, Zi
Li, Haoyang
Li, RongHua
Zheng, Huadi
Hu, Haibo
author_facet Xiao, Yaxin
Ye, Qingqing
Liang, Zi
Li, Haoyang
Li, RongHua
Zheng, Huadi
Hu, Haibo
contents Machine learning models constitute valuable intellectual property, yet remain vulnerable to model extraction attacks (MEA), where adversaries replicate their functionality through black-box queries. Model watermarking counters MEAs by embedding forensic markers for ownership verification. Current black-box watermarks prioritize MEA survival through representation entanglement, yet inadequately explore resilience against sequential MEAs and removal attacks. Our study reveals that this risk is underestimated because existing removal methods are weakened by entanglement. To address this gap, we propose Watermark Removal attacK (WRK), which circumvents entanglement constraints by exploiting decision boundaries shaped by prevailing sample-level watermark artifacts. WRK effectively reduces watermark success rates by at least 88.79% across existing watermarking benchmarks. For robust protection, we propose Class-Feature Watermarks (CFW), which improve resilience by leveraging class-level artifacts. CFW constructs a synthetic class using out-of-domain samples, eliminating vulnerable decision boundaries between original domain samples and their artifact-modified counterparts (watermark samples). CFW concurrently optimizes both MEA transferability and post-MEA stability. Experiments across multiple domains show that CFW consistently outperforms prior methods in resilience, maintaining a watermark success rate of at least 70.15% in extracted models even under the combined MEA and WRK distortion, while preserving the utility of protected models.
format Preprint
id arxiv_https___arxiv_org_abs_2511_07947
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Class-feature Watermark: A Resilient Black-box Watermark Against Model Extraction Attacks
Xiao, Yaxin
Ye, Qingqing
Liang, Zi
Li, Haoyang
Li, RongHua
Zheng, Huadi
Hu, Haibo
Cryptography and Security
Computer Vision and Pattern Recognition
Machine Learning
Machine learning models constitute valuable intellectual property, yet remain vulnerable to model extraction attacks (MEA), where adversaries replicate their functionality through black-box queries. Model watermarking counters MEAs by embedding forensic markers for ownership verification. Current black-box watermarks prioritize MEA survival through representation entanglement, yet inadequately explore resilience against sequential MEAs and removal attacks. Our study reveals that this risk is underestimated because existing removal methods are weakened by entanglement. To address this gap, we propose Watermark Removal attacK (WRK), which circumvents entanglement constraints by exploiting decision boundaries shaped by prevailing sample-level watermark artifacts. WRK effectively reduces watermark success rates by at least 88.79% across existing watermarking benchmarks. For robust protection, we propose Class-Feature Watermarks (CFW), which improve resilience by leveraging class-level artifacts. CFW constructs a synthetic class using out-of-domain samples, eliminating vulnerable decision boundaries between original domain samples and their artifact-modified counterparts (watermark samples). CFW concurrently optimizes both MEA transferability and post-MEA stability. Experiments across multiple domains show that CFW consistently outperforms prior methods in resilience, maintaining a watermark success rate of at least 70.15% in extracted models even under the combined MEA and WRK distortion, while preserving the utility of protected models.
title Class-feature Watermark: A Resilient Black-box Watermark Against Model Extraction Attacks
topic Cryptography and Security
Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2511.07947