Cryptology ePrint Archive: Report 2018/005

Simple and Efficient Two-Server ORAM

Xiao Wang and Dov Gordon and Jonathan Katz

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 applications to RAM-based secure computation.

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

Date: received 1 Jan 2018

Contact author: wangxiao at cs umd edu

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Version: 20180102:175031 (All versions of this report)

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