Functional encryption without obfuscation

Sanjam Garg, Craig Gentry, Shai Halevi, Mark Zhandry

Research output: Chapter in Book/Report/Conference proceedingConference contribution

51 Scopus citations

Abstract

Previously known functional encryption (FE) schemes for general circuits relied on indistinguishability obfuscation, which in turn either relies on an exponential number of assumptions (basically, one per circuit), or a polynomial set of assumptions, but with an exponential loss in the security reduction. Additionally most of these schemes are proved in the weaker selective security model, where the adversary is forced to specify its target before seeing the public parameters. For these constructions, full security can be obtained but at the cost of an exponential loss in the security reduction. In this work, we overcome the above limitations and realize an adaptively secure functional encryption scheme without using indistinguishability obfuscation. Specifically the security of our scheme relies only on the polynomial hardness of simple assumptions on composite order multilinear maps. Though we do not currently have secure instantiations for these assumptions, we expect that multilinear maps supporting these assumptions will discovered in the future. Alternatively, follow up results may yield constructions which can be securely instantiated. As a separate technical contribution of independent interest, we show how to add to existing graded encoding schemes a new extension function, that can be thought of as dynamically introducing new encoding levels.

Original languageEnglish (US)
Title of host publicationTheory of Cryptography - 3th International Conference, TCC 2016-A, Proceedings
EditorsTal Malkin, Eyal Kushilevitz
PublisherSpringer Verlag
Pages480-511
Number of pages32
ISBN (Print)9783662490983
DOIs
StatePublished - Jan 1 2016
Externally publishedYes
Event13th International Conference on Theory of Cryptography, TCC 2016 - Tel Aviv, Israel
Duration: Jan 10 2016Jan 13 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume9563
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Other

Other13th International Conference on Theory of Cryptography, TCC 2016
CountryIsrael
CityTel Aviv
Period1/10/161/13/16

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)

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