data protection officers

Abstract: Synthetic Data Generation (SDG) is an actively studied way to enable safe sharing of private data more broadly. Inference-only SDG methods, such as Private Evolution (PE), are particularly appealing, as they can leverage black-box access to pre-trained foundation models to generate high quality data without the need for model fine-tuning on the private data. PE is explicitly designed to produce synthetic data under Differential Privacy (DP). Yet formal DP guarantees do not eliminate the need for empirical privacy auditing of the practical susceptibility of released synthetic data to adversarial attacks. In this work, we introduce the first white-box Membership Inference Attack (MIA) tailored to the voting-based algorithm underlying the PE framework. By exploiting how the iterative filtering process biases the survival and proximity of synthetic candidates toward private instances, our attack achieves empirical performance indicating private data leakage in the PE applications across image, text, and tabular modalities.

Abstract: Retrieval-augmented generation (RAG) enables large language models to leverage external knowledge but introduces privacy risks when the retrieved corpus contains sensitive information. Differential privacy (DP) offers formal protection, yet interpreting and comparing privacy guarantees across existing DP-RAG methods remains challenging. In particular, a privacy budget reported for a single response does not directly characterize privacy loss over repeated queries, and even identical values of $\varepsilon$ may represent different guarantees depending on the protected data unit, accounting horizon, and observable outputs. This survey critically examines how privacy accounting evolves from single-query generation to multi-query RAG systems. We categorize existing approaches into query-time privatization, multi-query accounting, and one-time corpus privatization. We analyze their underlying assumptions and privacy--utility trade-offs. Rather than ranking methods by $\varepsilon$ alone, we propose a framework that interprets a DP-RAG guarantee along three dimensions: privacy granularity, accounting scope, and release boundaries. We conclude that an $\eps$ is a claim only together with the three slots: the protected unit, the accounting scope, and the release boundary.

Abstract: Privacy-enhancing technologies (PETs) have emerged as a technical means for providing individuals with greater control over their information. Yet despite the growing deployment of PETs, people continue to experience privacy harms. In this work, we revisit our understanding of privacy incidents and the realities of those experiencing privacy harms, to assess whether the goals and abilities of PETs are misaligned with the harms people face. For our study, we collect news articles that correspond to a sample of 257 real-world privacy incidents. We employ content analysis over the articles to develop a new information flow model that encompasses the complexity of data flows and their relation to resulting harms. We demonstrate that our model captures both established and novel aspects of privacy incidents and their mitigations. In particular, it captures why consent is often insufficient to prevent privacy violations, how harms emerge from complex interactions among multiple entities and actions, and reveals a flaw in our understanding of PETs: a focus on enabling functionalities still permits the harms inherent in those functionalities. Moreover, we find that the entities best positioned to implement harm-preventing measures for the incidents in our sample are the least incentivized to do so. Overall, our model and analysis identify limitations of privacy technology research for harm prevention and further identifies paths for transforming how we approach the advancement of these technologies.