Paper 2017/1142

PIR with compressed queries and amortized query processing

Sebastian Angel, Hao Chen, Kim Laine, and Srinath Setty

Abstract

Private information retrieval (PIR) is a key building block in many privacy-preserving systems. Unfortunately, existing constructions remain very expensive. This paper introduces two techniques that make the computational variant of PIR (CPIR) more efficient in practice. The first technique targets a recent class of CPU-efficient CPIR protocols where the query sent by the client contains a number of ciphertexts proportional to the size of the database. We show how to compresses this query, achieving size reductions of up to 274X. The second technique is a new data encoding called probabilistic batch codes (PBCs). We use PBCs to build a multi-query PIR scheme that allows the server to amortize its computational cost when processing a batch of requests from the same client. This technique achieves up to 40× speedup over processing queries one at a time, and is significantly more efficient than related encodings. We apply our techniques to the Pung private communication system, which relies on a custom multi-query CPIR protocol for its privacy guarantees. By porting our techniques to Pung, we find that we can simultaneously reduce network costs by 36× and increase throughput by 3X.

Note: This is the final version of our paper as it appears in S&P 2018.

Metadata
Available format(s)
PDF
Publication info
Published elsewhere. MINOR revision.IEEE Security and Privacy 2018 (Oakland)
Keywords
PIRprivate information retrievalbatch codes
Contact author(s)
sebs @ cs utexas edu
History
2018-04-01: last of 3 revisions
2017-11-27: received
See all versions
Short URL
https://ia.cr/2017/1142
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2017/1142,
      author = {Sebastian Angel and Hao Chen and Kim Laine and Srinath Setty},
      title = {PIR with compressed queries and amortized query processing},
      howpublished = {Cryptology ePrint Archive, Paper 2017/1142},
      year = {2017},
      note = {\url{https://eprint.iacr.org/2017/1142}},
      url = {https://eprint.iacr.org/2017/1142}
}
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