Cohort: Decentralized PIR

Private Information Retrieval (PIR) underpins privacy-preserving applications such as private content delivery, contact discovery, and anonymous advertising, where users need to discreetly query a database. However, PIR usually relies on expensive fully homomorphic encryption and scales poorly with the database size, making it difficult to deploy at scale. As a result, most PIR-based systems are expected to have a single provider, or a few, bearing the operational costs of running a limited number of servers. Such deployments are susceptible to provider takedowns, churn, DoS, and censorship, making availability fragile.