Publicly Verifiable Private Information Retrieval Protocols Based on Function Secret Sharing

2025-09-17

AI Summary

This paper addresses the fundamental challenge in private information retrieval (PIR)—the lack of result verifiability and the inherent tension between query privacy and data authenticity. To resolve this, we propose a novel publicly verifiable PIR (PVPIR) framework for the multi-server setting. Leveraging function secret sharing (FSS) and custom cryptographic protocols, we design two efficient PVPIR constructions: one supporting point queries with communication overhead substantially lower than Merkle-tree-based approaches, and another enabling expressive predicate queries with strong scalability. Our schemes achieve strong public verifiability—any third party can efficiently verify result correctness—strict query privacy under standard cryptographic assumptions, low computational cost, and stable communication complexity. Experimental evaluation confirms practicality on large-scale databases, demonstrating feasibility for real-world privacy-preserving query applications. This work establishes a new pathway toward deployable, verifiable PIR.

Technology Category

• Machine Learning: Privacy
• Computer Vision: Image and Video Retrieval
• Data Mining & Knowledge Management: Intelligent Query Processing

Application Category

• Security and Privacy: Privacy-enhancing technologies
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Responsible Web: Data and user privacy-enhancing technologies for the Web

Abstract

Private Information Retrieval (PIR) is a fundamental cryptographic primitive that enables users to retrieve data from a database without revealing which item is being accessed, thereby preserving query privacy. However, PIR protocols also face the challenge of result verifiability, as users expect the reconstructed data to be trustworthy and authentic. In this work, we propose two effective constructions of publicly verifiable PIR (PVPIR) in the multi-server setting, which achieve query privacy, correctness, and verifiability simultaneously. We further present three concrete instantiations based on these constructions. For the point query, our protocol introduces minimal computational overhead and achieves strong verifiability guarantees with significantly lower communication costs compared to existing Merkle tree-based approaches. For the predicate query, the communication complexity of our scheme remains stable as the database size increases, demonstrating strong scalability and suitability for large-scale private query applications.

Problem

• Achieving public verifiability in private information retrieval protocols
• Reducing communication costs for verifiable point queries
• Maintaining stable communication complexity for scalable predicate queries

Innovation

• Function Secret Sharing for PIR
• Publicly verifiable multi-server PIR
• Low communication cost predicate queries