arXiv AI
Sep 11

Watermarks Without Verification: AI Text Watermarking After the EU AI Act

The paper discusses the EU AI Act’s requirement for generative AI providers to embed detectable watermarks in their outputs, noting that Anthropic’s Claude models and Google’s Gemini use SynthID‑Text by default. It critiques the lack of verifiability of claims about watermark quality, privacy, and robustness, and evaluates the open‑source SynthID‑Text implementation on two open‑weight models, finding minimal impact on prose and modest correctness loss on code. The authors argue that the real governance issue is the inability to verify these assertions and outline necessary steps—such as output release, configuration disclosure, accredited audits, shared evaluation protocols, and interoperable detection—to address the gaps.

By Alexander Nemecek, Vipin Chaudhary, Erman Ayday
arXiv Computation and Language
6d ago

Watermarkability: Measuring and Improving Language-Model Compatibility with Logit-Based Watermarks

The paper introduces "watermarkability," a metric that quantifies how compatible a language model is with a logit‑based watermark that boosts the probability of a specified token set during decoding. By measuring the expected minimum KL divergence needed to achieve a target probability mass, the authors can assess and compare models and watermark rules. They propose a two‑stage approach—first training a low‑rank adapter conditioned on the target set, then applying a minimal uniform logit bias—to reduce this cost, achieving significant perplexity reductions across multiple watermark schedules on OPT‑125M and Qwen3‑8B.

By Zewei Deng, Mohamed Seif, Liyan Xie
arXiv Machine Learning
2d ago

MarkTune: Improving the Quality-Detectability Trade-off in Model-Embedded LLM Watermarking

MarkTune is a model‑embedded watermarking framework that improves the trade‑off between generation quality and detectability. By regularizing toward a high‑quality reference distribution, it decouples quality preservation from proximity to the base model and uses the GaussMark detection statistic as a reward during on‑policy fine‑tuning. Empirical results show that MarkTune enhances the quality‑detectability frontier, maintains downstream task performance, and remains robust against text‑editing and open‑weight attacks across diverse datasets.

By Yizhou Zhao, Zhiwei Steven Wu, Adam Block