Can we access a database both locally and privately?

Elette Boyle*, Yuval Ishai, Rafael Pass, Mary Wootters

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


We consider the following strong variant of private information retrieval (PIR). There is a large database x that we want to make publicly available. To this end, we post an encoding X of x together with a short public key pk in a publicly accessible repository. The goal is to allow any client who comes along to retrieve a chosen bit xi by reading a small number of bits from X, whose positions may be randomly chosen based on i and pk, such that even an adversary who can fully observe the access to X does not learn information about i. Towards solving this problem, we study a weaker secret key variant where the data is encoded and accessed by the same party. This primitive, that we call an oblivious locally decodable code (OLDC), is independently motivated by applications such as searchable symmetric encryption. We reduce the public-key variant of PIR to OLDC using an ideal form of obfuscation that can be instantiated heuristically with existing indistinguishability obfuscation candidates, or alternatively implemented with small and stateless tamper-proof hardware. Finally, a central contribution of our work is the first proposal of an OLDC candidate. Our candidate is based on a secretly permuted Reed-Muller code. We analyze the security of this candidate against several natural attacks and leave its further study to future work.

Original languageEnglish
Title of host publicationTheory of Cryptography - 15th International Conference, TCC 2017, Proceedings
EditorsYael Kalai, Leonid Reyzin
PublisherSpringer Verlag
Number of pages32
ISBN (Print)9783319705026
StatePublished - 2017
Externally publishedYes
Event15th International Conference on Theory of Cryptography, TCC 2017 - Baltimore, United States
Duration: 12 Nov 201715 Nov 2017

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume10678 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference15th International Conference on Theory of Cryptography, TCC 2017
Country/TerritoryUnited States


FundersFunder number
DIMACS/Simons Collaboration in Cryptography
NSF Frontier1228984, 1413955, 1065276, 1136174, 1619348
Air Force Office of Scientific ResearchFA9550-17-1-0069
Defense Advanced Research Projects Agency
Simons Foundation
Intel Corporation
Association of Research LibrariesFA9550-15-1-0262, CNS-1561209, CNS-1217821, W911NF-15-C-0205
European Research Council307952
United States-Israel Binational Science Foundation259426, 1709/14, 2012366, 742754
Israel Science Foundation1861/16
Okawa Foundation for Information and Telecommunications
National Science Foundation-1523467


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