Oblivis: A Framework for Delegated and Efficient Oblivious Transfer

2026-03-15

AI Summary

This work addresses the challenge of enabling resource-constrained lightweight clients in cloud and edge computing to securely delegate sensitive data queries. Existing oblivious transfer (OT) protocols neither support delegation nor are suitable for low-power devices. To bridge this gap, we propose Oblivis, the first OT framework that supports delegated queries. Oblivis builds a modular protocol stack leveraging multi-receiver OT, a constant-response-size compiler, and an information-theoretically secure Supersonic OT primitive, providing formal security guarantees in the simulation paradigm. Experimental results demonstrate that Supersonic OT achieves over 92× speedup compared to state-of-the-art efficient OT protocols across 200 to 100,000 invocations, and end-to-end delegated queries complete in just 1.36 ms on a Raspberry Pi 4, achieving both strong security and practical lightweight deployment.

Technology Category

• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Machine Learning: Hardware-aware ML

Application Category

• Security and Privacy: Data transparency and provenance
• Responsible Web: Data and user privacy-enhancing technologies for the Web
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

As database deployments shift toward cloud platforms and edge devices, thin clients need to securely retrieve sensitive records without leaking their query intent or metadata to the proxies that mediate access. Oblivious Transfer (OT) is a core tool for private retrieval, yet existing OTs assume direct client-database interaction and lack support for delegated querying or lightweight clients. We present Oblivis, a modular framework of new OT protocols that enable delegated, privacy-preserving query execution. Oblivis allows clients to retrieve database records without direct access, protects against leakage to both databases and proxies, and is designed with practical efficiency in mind. Its components include: (1) Delegated-Query OT, which permits secure outsourcing of query generation; (2) Multi-Receiver OT for merged, cloud-hosted databases; (3) a compiler producing constant-size responses suitable for thin clients; and (4) Supersonic OT, a proxy-based, informationtheoretic, and highly efficient 1-out-of-2 OT. The protocols are formally defined and proven secure in the simulation-based paradigm, under non-colluding assumption. We implement and empirically evaluate Supersonic OT. It achieves at least a 92x speedup over a highly efficient 1-out-of-2 OT, and a 2.6x-106x speedup over a standard OT extension across 200-100,000 invocations. Our implementation further shows that Supersonic OT remains efficient even on constrained hardware, e.g., it completes an end-to-end transfer in 1.36 ms on a Raspberry Pi 4.

Problem

• Oblivious Transfer
• Delegated Query
• Private Retrieval
• Thin Clients
• Metadata Leakage

Innovation

• Oblivious Transfer
• Delegated Query
• Supersonic OT
• Privacy-Preserving Retrieval
• Thin Client