Abstract
Private information retrieval (PIR) over Web 3.0 introduces a sophisticated dimension to data access and privacy protection. It enables users to retrieve specific information from databases without disclosing the exact data being accessed. In decentralized networks, where privacy and data security are critical, PIR techniques play a pivotal role in safeguarding user confidentiality. By employing cryptographic protocols, PIR ensures that users can query decentralized databases while preserving anonymity and preventing unauthorized data interception. This chapter delves into the intricate mechanics of PIR algorithms tailored for Web 3.0 environments, exploring how these techniques facilitate secure information retrieval and uphold privacy standards amidst distributed ledger technologies and decentralized applications (dApps). It examines the integration of PIR within emerging decentralized search engines, highlighting the advancements and challenges in deploying privacy-preserving mechanisms across decentralized networks.