INSPIRE: in-storage private information retrieval via protocol and architecture co-design

Private Information Retrieval (PIR) plays a vital role in secure, database-centric applications. However, existing PIR protocols explore a massive working space containing hundreds of GiBs of query and database data. As a consequence, PIR performance is severely bounded by storage communication, making it far from practical for real-world deployment. In this work, we describe INSPIRE, an accelerator for IN-Storage Private Information REtrieval. INSPIRE follows a protocol and architecture co-design approach. We first design the INSPIRE protocol with a multi-stage filtering mechanism, which achieves a constant PIR query size. For a 1-billion-entry database of size 288GiB, INSPIRE's protocol reduces the query size from 27GiB to 3.6MiB. Further, we propose the INSPIRE hardware, a heterogeneous in-storage architecture, which integrates our protocol across the SSD hierarchy. Together with the INSPIRE protocol, the INSPIRE hardware reduces the query time from 28.4min to 36s, relative to the the state-of-the-art FastPIR scheme.