Cryptology ePrint Archive: Report 2014/185

Oblivious Data Structures

Xiao Shaun Wang and Kartik Nayak and Chang Liu and T-H. Hubert Chan and Elaine Shi and Emil Stefanov and Yan Huang

Abstract: Oblivious RAMs (ORAMs) have traditionally been measured by their bandwidth overhead and client storage. We observe that when using ORAMs to build secure computation protocols for RAM programs, the size of the ORAM circuits is more relevant to the performance.

We therefore embark on a study of the circuit-complexity of several recently proposed ORAM constructions. Our careful implementation and experiments show that asymptotic analysis is not indicative of the true performance of ORAM in secure computation protocols with practical data sizes.

We then present SCORAM, a heuristic compact ORAM design optimized for secure computation protocols. Our new design is almost 10x smaller in circuit size and also faster than all other designs we have tested for realistic settings (i.e., memory sizes between 4MB and 2GB, constrained by 2^{-80} failure probability). SCORAM makes it feasible to perform secure computations on gigabyte-sized data sets.

Category / Keywords: cryptographic protocols / oblivious RAM, ORAM, secure computation

Original Publication (in the same form): CCS 2014
DOI:
10.1145/2660267.2660314

Date: received 9 Mar 2014, last revised 31 Oct 2014

Contact author: wangxiao at cs umd edu

Available format(s): PDF | BibTeX Citation

Version: 20141031:145230 (All versions of this report)

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