MUSE: Model-Agnostic Tabular Watermarking via Multi-Sample Selection

We introduce MUSE, a novel watermarking paradigm for tabular generative models. Existing approaches often exploit DDIM invertibility to watermark tabular diffusion models, but tabular diffusion models suffer from poor invertibility, leading to degraded performance. To overcome this limitation, we leverage the computational efficiency of tabular generative models and propose a multi-sample selection paradigm, where watermarks are embedded by generating multiple candidate samples and selecting one according to a specialized scoring function. The key advantages of MUSE include (1) Model-agnostic: compatible with any tabular generative model that supports repeated sampling; (2) Flexible: offers flexible designs to navigate the trade-off between generation quality, detectability, and robustness; (3) Calibratable: theoretical analysis provides principled calibration of watermarking strength, ensuring minimal distortion to the original data distribution. Extensive experiments on five datasets demonstrate that MUSE substantially outperforms existing methods. Notably, it reduces the distortion rates by 84-88% for fidelity metrics compared with the best performing baselines, while achieving 1.0 TPR@0.1%FPR detection rate.