  Deploying Machine Learning as a Service gives rise to model plagiarism,
leading to copyright infringement. Ownership testing techniques are designed to
identify model fingerprints for verifying plagiarism. However, previous works
often rely on overfitting or robustness features as fingerprints, lacking
theoretical guarantees and exhibiting under-performance on generalized models.
In this paper, we propose a novel ownership testing method called VeriDIP,
which verifies a DNN model's intellectual property. VeriDIP makes two major
contributions. (1) It utilizes membership inference attacks to estimate the
lower bound of privacy leakage, which reflects the fingerprint of a given
model. The privacy leakage fingerprints highlight the unique patterns through
which the models memorize sensitive training datasets. (2) We introduce a novel
approach using less private samples to enhance the performance of ownership
testing.
  Extensive experimental results confirm that VeriDIP is effective and
efficient in validating the ownership of deep learning models trained on both
image and tabular datasets. VeriDIP achieves comparable performance to
state-of-the-art methods on image datasets while significantly reducing
computation and communication costs. Enhanced VeriDIP demonstrates superior
verification performance on generalized deep learning models, particularly on
table-trained models. Additionally, VeriDIP exhibits similar effectiveness on
utility-preserving differentially private models compared to non-differentially
private baselines.
