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Proofs of retrievability via hardness amplification (2009)
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| Venue: | In TCC |
| Citations: | 83 - 4 self |
BibTeX
@INPROCEEDINGS{Dodis09proofsof,
author = {Yevgeniy Dodis and Salil Vadhan and Daniel Wichs},
title = {Proofs of retrievability via hardness amplification},
booktitle = {In TCC},
year = {2009}
}
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Abstract
Proofs of Retrievability (PoR), introduced by Juels and Kaliski [JK07], allow the client to store a file F on an untrusted server, and later run an efficient audit protocol in which the server proves that it (still) possesses the client’s data. Constructions of PoR schemes attempt to minimize the client and server storage, the communication complexity of an audit, and even the number of file-blocks accessed by the server during the audit. In this work, we identify several different variants of the problem (such as bounded-use vs. unbounded-use, knowledge-soundness vs. information-soundness), and giving nearly optimal PoR schemes for each of these variants. Our constructions either improve (and generalize) the prior PoR constructions, or give the first known PoR schemes with the required properties. In particular, we • Formally prove the security of an (optimized) variant of the bounded-use scheme of Juels and Kaliski [JK07], without making any simplifying assumptions on the behavior of the adversary. • Build the first unbounded-use PoR scheme where the communication complexity is linear in the security parameter and which does not rely on Random Oracles, resolving an open question of Shacham and Waters [SW08]. • Build the first bounded-use scheme with information-theoretic security. The main insight of our work comes from a simple connection between PoR schemes and the notion of hardness amplification, extensively studied in complexity theory. In particular, our improvements come from first abstracting a purely information-theoretic notion of PoR codes, and then building nearly optimal PoR codes using state-of-the-art tools from coding and complexity theory.
Keyphrases
hardness amplification por scheme communication complexity kaliski jk07 complexity theory main insight first unbounded-use por scheme open question bounded-use scheme untrusted server simple connection optimal por scheme security parameter water sw08 several different variant client data server storage random oracle efficient audit protocol por code required property first bounded-use scheme bounded-use v information-theoretic security simplifying assumption information-theoretic notion state-of-the-art tool knowledge-soundness v prior por construction optimal por code
