1. Simple and Efficient Two-Server ORAM 2018 Asiacrypt ORAM PIR
    S. Dov Gordon and Jonathan Katz and Xiao Wang
    [View PDF on eprint.iacr.org]
    [Show BibTex Citation]

    author = {S. Dov Gordon and Jonathan Katz and Xiao Wang},
    title = {Simple and Efficient Two-Server ORAM},
    howpublished = {Cryptology ePrint Archive, Report 2018/005},
    year = {2018},
    note = {\url{https://eprint.iacr.org/2018/005}},

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 λ, the servers each store 4N encrypted blocks, the client stores λ+2logN blocks, and the total communication per logical access is roughly 10logN encrypted blocks.