Cryptology ePrint Archive: Report 2017/914

Cache-Oblivious and Data-Oblivious Sorting and Applications

T-H. Hubert Chan and Yue Guo and Wei-Kai Lin and Elaine Shi

Abstract: Although external-memory sorting has been a classical algorithms abstraction and has been heavily studied in the literature, perhaps somewhat surprisingly, when data-obliviousness is a requirement, even very rudimentary questions remain open. Prior to our work, it is not even known how to construct a comparison-based, external-memory oblivious sorting algorithm that is optimal in IO-cost.

We make a significant step forward in our understanding of external-memory, oblivious sorting algorithms. Not only do we construct a comparison-based, external-memory oblivious sorting algorithm that is optimal in IO-cost, our algorithm is also cache-agnostic in that the algorithm need not know the storage hierarchy's internal parameters such as the cache and cache-line sizes. Our result immediately implies a cache-agnostic ORAM construction whose asymptotical IO-cost matches the best known cache-aware scheme.

Last but not the least, we propose and adopt a new and stronger security notion for external-memory, oblivious algorithms and argue that this new notion is desirable for resisting possible cache-timing attacks. Thus our work also lays a foundation for the study of oblivious algorithms in the cache-agnostic model.

Category / Keywords: foundations / cache oblivious algorithms, data oblivious algorithms, ORAM

Date: received 19 Sep 2017, last revised 24 Sep 2017

Contact author: hubert at cs hku hk

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Version: 20170924:221449 (All versions of this report)

Short URL: ia.cr/2017/914

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