  In a data-driven world, datasets constitute a significant economic value.
Dataset owners who spend time and money to collect and curate the data are
incentivized to ensure that their datasets are not used in ways that they did
not authorize. When such misuse occurs, dataset owners need technical
mechanisms for demonstrating their ownership of the dataset in question.
Dataset watermarking provides one approach for ownership demonstration which
can, in turn, deter unauthorized use. In this paper, we investigate a recently
proposed data provenance method, radioactive data, to assess if it can be used
to demonstrate ownership of (image) datasets used to train machine learning
(ML) models. The original paper reported that radioactive data is effective in
white-box settings. We show that while this is true for large datasets with
many classes, it is not as effective for datasets where the number of classes
is low $(\leq 30)$ or the number of samples per class is low $(\leq 500)$. We
also show that, counter-intuitively, the black-box verification technique is
effective for all datasets used in this paper, even when white-box verification
is not. Given this observation, we show that the confidence in white-box
verification can be improved by using watermarked samples directly during the
verification process. We also highlight the need to assess the robustness of
radioactive data if it were to be used for ownership demonstration since it is
an adversarial setting unlike provenance identification.
  Compared to dataset watermarking, ML model watermarking has been explored
more extensively in recent literature. However, most of the model watermarking
techniques can be defeated via model extraction. We show that radioactive data
can effectively survive model extraction attacks, which raises the possibility
that it can be used for ML model ownership verification robust against model
extraction.
