Authors: 1Antoni Kowalczuk*, 2,3Jan Dubiński*, 1Franziska Boenisch, 1Adam Dziedzic

1CISPA Helmholtz Center for Information Security
2Warsaw University of Technology
3IDEAS NCBR

*Indicates Equal Contribution

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Privacy-utility and generation speed-performance trade-off for Image AutoRegressive Models (IARs) compared to Diffusion Models (DMs.)

Abstract

Image AutoRegressive generation has emerged as a new powerful paradigm with image autoregressive models (IARs) surpassing state-of-the-art diffusion models (DMs) in both image quality (FID: 1.48 vs. 1.58) and generation speed. However, the privacy risks associated with IARs remain unexplored, raising concerns regard- ing their responsible deployment. To address this gap, we conduct a comprehensive privacy analysis of IARs, comparing their privacy risks to the ones of DMs as reference points. Concretely, we develop a novel membership inference attack (MIA) that achieves a remarkably high success rate in detecting training images (with a TPR@FPR=1% of 86.38% vs. 4.91% for DMs with comparable attacks). We leverage our novel MIA to provide dataset inference (DI) for IARs, and show that it requires as few as 6 samples to detect dataset membership (compared to 200 for DI in DMs), confirming a higher information leakage in IARs. Finally, we are able to extract hundreds of training data points from an IAR (e.g., 698 from VAR-d30). Our results demonstrate a fundamental privacy-utility trade-off: while IARs excel in image generation quality and speed, they are significantly more vulnerable to privacy attacks compared to DMs. This trend suggests that utilizing techniques from DMs within IARs, such as modeling the per-token probability distribution using a diffusion procedure, holds potential to help mitigating IARs’ vulnerability to privacy attacks.

Contributions

  • Our new MIA for IARs achieves extremely strong performance of even 86.38% TPR@FPR, improving over naive application of MIAs by up to 69%.
  • We provide a potent DI method for IARs, which requires as few as 6 samples to assess dataset membership signal.
  • We propose an efficient method of training data extraction from IARs, and successfully extract up to 698 images.
  • IARs outperform DMs in generation efficiency and quality but suffer order-of-magnitude higher privacy leakage compared to them in MIAs, DI, and data extraction.

Membership Inference Attacks Results

Model VAR-d16 VAR-d20 VAR-d24 VAR-d30 MAR-B MAR-L MAR-H RAR-B RAR-L RAR-XL RAR-XXL
Baselines 1.62 2.21 3.72 16.68 1.69 1.89 2.18 2.36 3.25 6.27 14.62
Our Methods 2.16 5.95 24.03 86.38 2.09 2.61 3.40 4.30 8.66 26.14 49.80
Improvement +0.54 +3.73 +20.30 +69.69 +0.40 +0.73 +1.22 +1.94 +5.41 +19.87 +35.17

We improve over baseline Membership Inference Attacks by up to 69.69% for VAR-d30.

Dataset Inference Results

Model VAR-d16 VAR-d20 VAR-d24 VAR-d30 MAR-B MAR-L MAR-H RAR-B RAR-L RAR-XL RAR-XXL
Baseline 2000 300 60 20 5000 2000 900 500 200 40 30
+Optimized Procedure 600 200 40 8 4000 2000 800 300 80 30 10
Improvement -1400 -100 -20 -12 -1000 0 -100 -200 -120 -10 -20
+Our MIAs for IARs 200 40 20 6 2000 600 300 80 30 20 8
Improvement -400 -160 -20 -2 -2000 -1400 -500 -220 -50 -10 -2

Data Extraction

We successfully perform data extraction attack against IARs, extracting up to 698 images. We extract 698 images for VAR-d30, 5 images for MAR-H, and 36 images for RAR-XXL.

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Extracted Training Samples. IARs can reconstruct verbatim images from their training data. The first row shows the original training samples, and the second presents the extracted images.

Bibtex

@misc{kowalczuk2025privacyattacksimageautoregressive,
      title={Privacy Attacks on Image AutoRegressive Models}, 
      author={Antoni Kowalczuk and Jan Dubiński and Franziska Boenisch and Adam Dziedzic},
      year={2025},
      eprint={2502.02514},
      archivePrefix={arXiv},
      primaryClass={cs.CV},
      url={https://arxiv.org/abs/2502.02514}, 
}