Cryptology ePrint Archive: Report 2015/1126

A Practical Oblivious Map Data Structure with Secure Deletion and History Independence

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

Abstract: We present a new oblivious RAM that supports variable-sized storage blocks (vORAM), which is the first ORAM to allow varying block sizes without trivial padding. We also present a new history-independent data structure (a HIRB tree) that can be stored within a vORAM. Together, this construction provides an efficient and practical oblivious data structure (ODS) for a key/value map, and goes further to provide an additional privacy guarantee as compared to prior ODS maps: even upon client compromise, deleted data and the history of old operations remain hidden to the attacker.

We implement and measure the performance of our system using Amazon Web Services, and the single-operation time for a realistic database (up to $2^{18}$ entries) is less than 1 second. This represents a 100x speed-up compared to the current best oblivious map data structure (which provides neither secure deletion nor history independence) by Wang et al. (CCS 14).

Category / Keywords: cryptographic protocols / oblivious RAM, ORAM, oblivious data structures, ODS, secure deletion

Date: received 20 Nov 2015, last revised 22 Nov 2015

Contact author: roche at usna edu

Available format(s): PDF | BibTeX Citation

Note: Fixed missing references.

Version: 20151122:212155 (All versions of this report)

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