Non-malleable extractors with shorter seeds and their applications

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Abstract

Motivated by the problem of how to communicate over a public channel with an active adversary, Dodis and Wichs (STOC’09) introduced the notion of a non-malleable extractor. A non-malleable extractor nmExt: {0, 1}n×{0, 1}d→ {0, 1}mtakes two inputs, a weaklyrandom W and a uniformly random seed S, and outputs a string which is nearly uniform, given S as well as nmExt(W,A(S)), for an arbitrary function A with A(S) ≠ S. In this paper, by developing the combination and permutation techniques, we improve the error estimation of the extractor of Raz (STOC’05), which plays an extremely important role in the constraints of the non-malleable extractor parameters including seed length. Then we present improved explicit construction of non-malleable extractors. Though our construction is the same as that given by Cohen, Raz and Segev (CCC’12), the parameters are improved. More precisely, we construct an explicit (1016, (formula presented)-non-malleable extractor nmExt: {0, 1}n× {0, 1}d→ {0, 1} with n = 210and seed length d = 19, while Cohen et al. showed that the seed length is no less than (formula presented)+66. Therefore, our method beats the condition “2.01 ・ log n ≤ d ≤ n” proposed by Cohen et al., since d is just 1.9 ・ log n in our construction. We also improve the parameters of the general explicit construction given by Cohen et al. Finally, we give their applications to privacy amplification.

Original languageEnglish
Title of host publicationProgress in Cryptology – INDOCRYPT 2015 - 16th International Conference on Cryptology in India, Proceedings
EditorsAlex Biryukov, Vipul Goyal
PublisherSpringer Verlag
Pages293-311
Number of pages19
ISBN (Print)9783319266169
DOIs
StatePublished - 2015
Event16th International Conference on Cryptology in India, INDOCRYPT 2015 - Bangalore, India
Duration: 6 Dec 20159 Dec 2015

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume9462
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference16th International Conference on Cryptology in India, INDOCRYPT 2015
Country/TerritoryIndia
CityBangalore
Period6/12/159/12/15

Keywords

  • Extractors
  • Non-malleable extractors
  • Privacy amplification protocol
  • Seed length

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