Cryptology ePrint Archive: Report 2017/586

Deterministic, Stash-Free Write-Only ORAM

Daniel S. Roche and Adam J. Aviv and Seung Geol Choi and Travis Mayberry

Abstract: Write-Only Oblivious RAM (WoORAM) protocols provide privacy by encrypting the contents of data and also hiding the pattern of write operations over that data. WoORAMs provide better privacy than plain encryption and better performance than more general ORAM schemes (which hide both writing and reading access patterns), and the write-oblivious setting has been applied to important applications of cloud storage synchronization and encrypted hidden volumes. In this paper, we introduce an entirely new technique for Write-Only ORAM, called DetWoORAM. Unlike previous solutions, DetWoORAM uses a deterministic, sequential writing pattern without the need for any "stashing" of blocks in local state when writes fail. Our protocol, while conceptually simple, provides substantial improvement over prior solutions, both asymptotically and experimentally. In particular, under typical settings the DetWoORAM writes only 2 blocks (sequentially) to backend memory for each block written to the device, which is optimal. We have implemented our solution using the BUSE (block device in user-space) module and tested DetWoORAM against both an encryption only baseline of dm-crypt and prior, randomized WoORAM solutions, measuring only a 3x-14x slowdown compared to an encryption-only baseline and around 6x-19x speedup compared to prior work.

Category / Keywords: cryptographic protocols; ORAM

Original Publication (in the same form): Proc. ACM Conf. on Computer and Communications Security (CCS) 2017

Date: received 15 Jun 2017, last revised 7 Sep 2017

Contact author: roche at usna edu

Available format(s): PDF | BibTeX Citation

Version: 20170907:092210 (All versions of this report)

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