AgentMark: Utility-Preserving Behavioral Watermarking for Agents

Fuente: arXiv
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Main Authors: Huang, Kaibo, Tan, Jin, Wei, Yukun, Li, Wanling, Zhang, Zipei, Tian, Hui, Yang, Zhongliang, Zhou, Linna
Format: Preprint
Published: 2026
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_version_ 1866913058737094656
author Huang, Kaibo
Tan, Jin
Wei, Yukun
Li, Wanling
Zhang, Zipei
Tian, Hui
Yang, Zhongliang
Zhou, Linna
author_facet Huang, Kaibo
Tan, Jin
Wei, Yukun
Li, Wanling
Zhang, Zipei
Tian, Hui
Yang, Zhongliang
Zhou, Linna
contents LLM-based agents are increasingly deployed to autonomously solve complex tasks, raising urgent needs for IP protection and regulatory provenance. While content watermarking effectively attributes LLM-generated outputs, it fails to directly identify the high-level planning behaviors (e.g., tool and subgoal choices) that govern multi-step execution. Critically, watermarking at the planning-behavior layer faces unique challenges: minor distributional deviations in decision-making can compound during long-term agent operation, degrading utility, and many agents operate as black boxes that are difficult to intervene in directly. To bridge this gap, we propose AgentMark, a behavioral watermarking framework that embeds multi-bit identifiers into planning decisions while preserving utility. It operates by eliciting an explicit behavior distribution from the agent and applying distribution-preserving conditional sampling, enabling deployment under black-box APIs while remaining compatible with action-layer content watermarking. Experiments across embodied, tool-use, and social environments demonstrate practical multi-bit capacity, robust recovery from partial logs, and utility preservation. The code is available at https://github.com/Tooooa/AgentMark.
format Preprint
id arxiv_https___arxiv_org_abs_2601_03294
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle AgentMark: Utility-Preserving Behavioral Watermarking for Agents
Huang, Kaibo
Tan, Jin
Wei, Yukun
Li, Wanling
Zhang, Zipei
Tian, Hui
Yang, Zhongliang
Zhou, Linna
Cryptography and Security
Artificial Intelligence
LLM-based agents are increasingly deployed to autonomously solve complex tasks, raising urgent needs for IP protection and regulatory provenance. While content watermarking effectively attributes LLM-generated outputs, it fails to directly identify the high-level planning behaviors (e.g., tool and subgoal choices) that govern multi-step execution. Critically, watermarking at the planning-behavior layer faces unique challenges: minor distributional deviations in decision-making can compound during long-term agent operation, degrading utility, and many agents operate as black boxes that are difficult to intervene in directly. To bridge this gap, we propose AgentMark, a behavioral watermarking framework that embeds multi-bit identifiers into planning decisions while preserving utility. It operates by eliciting an explicit behavior distribution from the agent and applying distribution-preserving conditional sampling, enabling deployment under black-box APIs while remaining compatible with action-layer content watermarking. Experiments across embodied, tool-use, and social environments demonstrate practical multi-bit capacity, robust recovery from partial logs, and utility preservation. The code is available at https://github.com/Tooooa/AgentMark.
title AgentMark: Utility-Preserving Behavioral Watermarking for Agents
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2601.03294