Constants Count: Practical Improvements to Oblivious RAM

Ling Ren; Christopher W.  Fletcher; Albert Kwon; Emil Stefanov; Elaine Shi; Marten van Dijk; Srinivas Devadas

Paper 2014/997

Constants Count: Practical Improvements to Oblivious RAM

Ling Ren, Christopher W. Fletcher, Albert Kwon, Emil Stefanov, Elaine Shi, Marten van Dijk, and Srinivas Devadas

Abstract

Oblivious RAM (ORAM) is a cryptographic primitive that hides memory access patterns as seen by untrusted storage. This paper proposes Ring ORAM, the most bandwidth-efficient ORAM scheme for the small client storage setting in both theory and practice. Ring ORAM is the first tree-based ORAM whose bandwidth is independent of the ORAM bucket size, a property that unlocks multiple performance improvements. First, Ring ORAM’s overall bandwidth is 2.3x to 4x better than Path ORAM, the prior-art scheme for small client storage. Second, if memory can perform simple untrusted computation, Ring ORAM achieves constant online bandwidth (~60x improvement over Path ORAM for practical parameters). As a case study, we show Ring ORAM speeds up program completion time in a secure processor by 1.5x relative to Path ORAM. On the theory side, Ring ORAM features a tighter and significantly simpler analysis than Path ORAM.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Published elsewhere. usenix 2015
Contact author(s): renling @ mit edu
History: 2015-07-07: revised; 2014-12-18: received; See all versions
Short URL: https://ia.cr/2014/997
License: CC BY

BibTeX

@misc{cryptoeprint:2014/997,
      author = {Ling Ren and Christopher W.  Fletcher and Albert Kwon and Emil Stefanov and Elaine Shi and Marten van Dijk and Srinivas Devadas},
      title = {Constants Count: Practical Improvements to Oblivious {RAM}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2014/997},
      year = {2014},
      url = {https://eprint.iacr.org/2014/997}
}