arXiv subjects

Zhiru Zhu

Publications and source records attributed to Zhiru Zhu.

4 recordsLinked to original sources

arXiv2026

Within-Dataset Disclosure Risk for Differential Privacy

Differential privacy (DP) enables private data analysis. In a typical DP deployment, controllers manage individuals' sensitive data and are responsible for answering analysts' queries while protecting individuals' privacy. They do so by choosing the privacy parameter $ε$, which controls the degree of privacy for all individuals in all possible datasets. However, it is challenging for controllers to choose $ε$ because of the difficulty of interpreting the privacy implications of such a choice on the within-dataset individuals. To address this challenge, we first derive a relative disclosure risk indicator (RDR) that indicates the impact of choosing $ε$ on the within-dataset individuals' disclosure risk. We then design an algorithm to find $ε$ based on controllers' privacy preferences expressed as a function of the within-dataset individuals' RDRs, and an alternative algorithm that finds and releases $ε$ while satisfying DP. Lastly, we propose a solution that bounds the total privacy leakage when using the algorithm to answer multiple queries without requiring controllers to set the total privacy budget. We evaluate our contributions through an IRB-approved user study that shows the RDR is useful for helping controllers choose $ε$, and experimental evaluations showing our algorithms are efficient and scalable.

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arXiv2024

Enabling Personal Dataflow Sovereignty via Bolt-on Data Escrow

The digital economy is powered by a continuous and massive exchange of personal data. Individuals provide data to platforms in return for services, from social networking and search to health monitoring, entertainment, and access to LLMs. This exchange has created immense value, but it has also established a fundamental asymmetry of power: individuals possess only coarse-grained control over data access rather than fine-grained control over its purpose of use, creating a gap where data can be repurposed for undisclosed uses, e.g., platforms selling the data to data brokers, which results in a critical loss of personal data sovereignty. This paper frames this socio-technical challenge as a dataflow management problem. We propose a bolt-on data escrow architecture through delegated computation. In our model, instead of data flowing to platforms, platforms delegate their computation to a trustworthy escrow. This inversion empowers individuals with transparency and control over their dataflows. We present four contributions: (1) a dataflow model that explicitly incorporates computational purpose as a first-class primitive; (2) a minimally invasive programming interface, run(access(), compute()), built on a unified relational interface that virtualizes on-device data sources and a computation offloading component; (3) a concrete implementation of our escrow within the Apple ecosystem, demonstrating its practicality; and (4) both qualitative and quantitative evaluations demonstrating that our solution is expressive enough to implement a wide range of dataflows from real-world applications and introduces minimal runtime overhead. In summary, our work serves as a stepping stone toward achieving personal dataflow sovereignty.

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arXiv2023

Data Station: Delegated, Trustworthy, and Auditable Computation to Enable Data-Sharing Consortia with a Data Escrow

Pooling and sharing data increases and distributes its value. But since data cannot be revoked once shared, scenarios that require controlled release of data for regulatory, privacy, and legal reasons default to not sharing. Because selectively controlling what data to release is difficult, the few data-sharing consortia that exist are often built around data-sharing agreements resulting from long and tedious one-off negotiations. We introduce Data Station, a data escrow designed to enable the formation of data-sharing consortia. Data owners share data with the escrow knowing it will not be released without their consent. Data users delegate their computation to the escrow. The data escrow relies on delegated computation to execute queries without releasing the data first. Data Station leverages hardware enclaves to generate trust among participants, and exploits the centralization of data and computation to generate an audit log. We evaluate Data Station on machine learning and data-sharing applications while running on an untrusted intermediary. In addition to important qualitative advantages, we show that Data Station: i) outperforms federated learning baselines in accuracy and runtime for the machine learning application; ii) is orders of magnitude faster than alternative secure data-sharing frameworks; and iii) introduces small overhead on the critical path.

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arXiv2022

Ver: View Discovery in the Wild

We present Ver, a data discovery system that identifies project-join views over large repositories of tables that do not contain join path information, and even when input queries are inaccurate. Ver implements a reference architecture to solve both the technical (scale and search) and human (semantic ambiguity, navigating a large number of results) problems of view discovery. We demonstrate users find the view they want when using Ver with a user study and we demonstrate its performance with large-scale end-to-end experiments on real-world datasets containing tens of millions of join paths.

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