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2-Server PIR with subpolynomial communication

Author(s): Dvir, Zeev; Gopi, Sivakanth

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Abstract: A 2-server Private Information Retrieval (PIR) scheme allows a user to retrieve the ith bit of an n-bit database replicated among two noncommunicating servers, while not revealing any information about i to either server. In this work, we construct a 2-server PIR scheme with total communication cost no(√log log n/log n). This improves over current 2-server protocols, which all require Ω(n1/3) communication. Our construction circumvents the n1/3 barrier of Razborov and Yekhanin [2007], which holds for the restricted model of bilinear group-based schemes (covering all previous 2-server schemes). The improvement comes from reducing the number of servers in existing protocols, based on Matching Vector Codes, from 3 or 4 servers to 2. This is achieved by viewing these protocols in an algebraic way (using polynomial interpolation) and extending them using partial derivatives.
Publication Date: 8-Nov-2016
Electronic Publication Date: 2016
Citation: Dvir, Z, Gopi, S. (2016). 2-Server PIR with subpolynomial communication. Journal of the ACM, 63 (10.1145/2968443
DOI: doi:10.1145/2968443
Type of Material: Journal Article
Journal/Proceeding Title: Journal of the ACM
Version: Author's manuscript

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