AgentStealth: Reinforcing Large Language Model for Anonymizing User-generated Text

Fuente: arXiv
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Autores principales: Shao, Chenyang, Li, Tianxing, Pu, Chenhao, Xu, Fengli, Li, Yong
Formato: Preprint
Publicado: 2025
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author Shao, Chenyang
Li, Tianxing
Pu, Chenhao
Xu, Fengli
Li, Yong
author_facet Shao, Chenyang
Li, Tianxing
Pu, Chenhao
Xu, Fengli
Li, Yong
contents In today's digital world, casual user-generated content often contains subtle cues that may inadvertently expose sensitive personal attributes. Such risks underscore the growing importance of effective text anonymization to safeguard individual privacy. However, existing methods either rely on rigid replacements that damage utility or cloud-based LLMs that are costly and pose privacy risks. To address these issues, we explore the use of locally deployed smaller-scale language models (SLMs) for anonymization. Yet training effective SLMs remains challenging due to limited high-quality supervision. To address the challenge, we propose AgentStealth, a self-reinforcing LLM anonymization framework.First, we introduce an adversarial anonymization workflow enhanced by In-context Contrastive Learning and Adaptive Utility-Aware Control. Second, we perform supervised adaptation of SLMs using high-quality data collected from the workflow, which includes both anonymization and attack signals. Finally, we apply online reinforcement learning where the model leverages its internal adversarial feedback to iteratively improve anonymization performance. Experiments on two datasets show that our method outperforms baselines in both anonymization effectiveness (+12.3%) and utility (+6.8%). Our lightweight design supports direct deployment on edge devices, avoiding cloud reliance and communication-based privacy risks. Our code is open-source at https://github.com/tsinghua-fib-lab/AgentStealth.
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id arxiv_https___arxiv_org_abs_2506_22508
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publishDate 2025
record_format arxiv
spellingShingle AgentStealth: Reinforcing Large Language Model for Anonymizing User-generated Text
Shao, Chenyang
Li, Tianxing
Pu, Chenhao
Xu, Fengli
Li, Yong
Computation and Language
Artificial Intelligence
In today's digital world, casual user-generated content often contains subtle cues that may inadvertently expose sensitive personal attributes. Such risks underscore the growing importance of effective text anonymization to safeguard individual privacy. However, existing methods either rely on rigid replacements that damage utility or cloud-based LLMs that are costly and pose privacy risks. To address these issues, we explore the use of locally deployed smaller-scale language models (SLMs) for anonymization. Yet training effective SLMs remains challenging due to limited high-quality supervision. To address the challenge, we propose AgentStealth, a self-reinforcing LLM anonymization framework.First, we introduce an adversarial anonymization workflow enhanced by In-context Contrastive Learning and Adaptive Utility-Aware Control. Second, we perform supervised adaptation of SLMs using high-quality data collected from the workflow, which includes both anonymization and attack signals. Finally, we apply online reinforcement learning where the model leverages its internal adversarial feedback to iteratively improve anonymization performance. Experiments on two datasets show that our method outperforms baselines in both anonymization effectiveness (+12.3%) and utility (+6.8%). Our lightweight design supports direct deployment on edge devices, avoiding cloud reliance and communication-based privacy risks. Our code is open-source at https://github.com/tsinghua-fib-lab/AgentStealth.
title AgentStealth: Reinforcing Large Language Model for Anonymizing User-generated Text
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2506.22508