Single-server client preprocessing private information retrieval with tight space-time trade-off

Private Information Retrieval (PIR) studies the problem of retrieving an entry from a public database without revealing the index of the entry to the server. This thesis partly solves the open problem of tight trade-off of client storage and server time in the client preprocessing setting of PIR. In the client preprocessing setting of PIR, the client is allowed to store some hints generated from the database in a preprocessing phase and use the hints to assist online queries. We construct a new single-server client preprocessing PIR scheme. For a database with n entries of size w, our protocol uses S=O((n/T) * (log n + w)) bits of client storage and T amortized server probes over n/T queries, where T is a tunable online time parameter. Our scheme matches (up to constant factors) a ST = Omega(nw) lower bound generalized from a recent work by Yeo and a communication barrier generalized from Ishai, Shi, and Wichs. From a technical standpoint, we present a novel organization of hints where each PIR query consumes a hint, and entries in the consumed hint are relocated to other hints. We then present a new data structure to track the hint relocations and use small-domain pseudorandom permutations to make the hint storage sublinear while maintaining efficient lookups in the hints.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Computer Science

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Wang, Zhikun

Contributors dc:contributor

• Ren, Ling

• Private Information Retrieval

Statement dc:rights

• Copyright 2024 Zhikun Wang

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127489

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127489