Distributional Information Embedding: A Framework for Multi-bit Watermarking

Fuente: arXiv
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Main Authors: He, Haiyun, Liu, Yepeng, Wang, Ziqiao, Mao, Yongyi, Bu, Yuheng
Format: Preprint
Published: 2025
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author He, Haiyun
Liu, Yepeng
Wang, Ziqiao
Mao, Yongyi
Bu, Yuheng
author_facet He, Haiyun
Liu, Yepeng
Wang, Ziqiao
Mao, Yongyi
Bu, Yuheng
contents This paper introduces a novel problem, distributional information embedding, motivated by the practical demands of multi-bit watermarking for large language models (LLMs). Unlike traditional information embedding, which embeds information into a pre-existing host signal, LLM watermarking actively controls the text generation process--adjusting the token distribution--to embed a detectable signal. We develop an information-theoretic framework to analyze this distributional information embedding problem, characterizing the fundamental trade-offs among three critical performance metrics: text quality, detectability, and information rate. In the asymptotic regime, we demonstrate that the maximum achievable rate with vanishing error corresponds to the entropy of the LLM's output distribution and increases with higher allowable distortion. We also characterize the optimal watermarking scheme to achieve this rate. Extending the analysis to the finite-token case with non-i.i.d. tokens, we identify schemes that maximize detection probability while adhering to constraints on false alarm and distortion.
format Preprint
id arxiv_https___arxiv_org_abs_2501_16558
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Distributional Information Embedding: A Framework for Multi-bit Watermarking
He, Haiyun
Liu, Yepeng
Wang, Ziqiao
Mao, Yongyi
Bu, Yuheng
Cryptography and Security
Information Theory
Machine Learning
This paper introduces a novel problem, distributional information embedding, motivated by the practical demands of multi-bit watermarking for large language models (LLMs). Unlike traditional information embedding, which embeds information into a pre-existing host signal, LLM watermarking actively controls the text generation process--adjusting the token distribution--to embed a detectable signal. We develop an information-theoretic framework to analyze this distributional information embedding problem, characterizing the fundamental trade-offs among three critical performance metrics: text quality, detectability, and information rate. In the asymptotic regime, we demonstrate that the maximum achievable rate with vanishing error corresponds to the entropy of the LLM's output distribution and increases with higher allowable distortion. We also characterize the optimal watermarking scheme to achieve this rate. Extending the analysis to the finite-token case with non-i.i.d. tokens, we identify schemes that maximize detection probability while adhering to constraints on false alarm and distortion.
title Distributional Information Embedding: A Framework for Multi-bit Watermarking
topic Cryptography and Security
Information Theory
Machine Learning
url https://arxiv.org/abs/2501.16558