Cryptology ePrint Archive: Report 2018/005
Simple and Efficient Two-Server ORAM
S. Dov Gordon and Jonathan Katz and Xiao Wang
Abstract: We show a protocol for two-server oblivious RAM (ORAM) that is
simpler and more efficient than the best prior work. Our
construction combines any tree-based ORAM with an extension of
a two-server private information retrieval scheme by Boyle et
al., and is able to avoid recursion and thus use only one round
of interaction. In addition, our scheme has a very cheap
initialization phase, making it well suited for RAM-based
secure computation. Although our scheme requires the servers to
perform a linear scan over the entire data, the cryptographic
computation involved consists only of block-cipher evaluations.
A practical instantiation of our protocol has excellent
concrete parameters: for storing an $N$-element array of
arbitrary size data blocks with statistical security
parameter $\lambda$, the servers each store $4N$ encrypted
blocks, the client stores $\lambda+2\log N$ blocks, and the
total communication per logical access is roughly $10 \log N$
encrypted blocks.
Category / Keywords: cryptographic protocols / ORAM, single-round, multi-party computation, RAM model
Original Publication (in the same form): Asiacrypt 2018
Date: received 1 Jan 2018, last revised 5 Sep 2018
Contact author: wangxiao at cs umd edu
Available format(s): PDF | BibTeX Citation
Version: 20180905:183434 (All versions of this report)
Short URL: ia.cr/2018/005
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