Oblivious RAM with O((logN)3) Worst-Case Cost

  • Elaine Shi
  • T. -H. Hubert Chan
  • Emil Stefanov
  • Mingfei Li
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7073)


Oblivious RAM is a useful primitive that allows a client to hide its data access patterns from an untrusted server in storage outsourcing applications. Until recently, most prior works on Oblivious RAM aim to optimize its amortized cost, while suffering from linear or even higher worst-case cost. Such poor worst-case behavior renders these schemes impractical in realistic settings, since a data access request can occasionally be blocked waiting for an unreasonably large number of operations to complete.

This paper proposes novel Oblivious RAM constructions that achieves poly-logarithmic worst-case cost, while consuming constant client-side storage. To achieve the desired worst-case asymptotic performance, we propose a novel technique in which we organize the O-RAM storage into a binary tree over data buckets, while moving data blocks obliviously along tree edges.


Leaf Node Binary Tree Index Structure Data Block Amortize Cost 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© International Association for Cryptologic Research 2011

Authors and Affiliations

  • Elaine Shi
    • 1
  • T. -H. Hubert Chan
    • 2
  • Emil Stefanov
    • 3
  • Mingfei Li
    • 2
  1. 1.UC Berkeley/PARCUSA
  2. 2.The University of Hong KongHong Kong
  3. 3.UC BerkeleyUSA

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