Obfuscating point functions with multibit output

Ran Canetti, Ronny Ramzi Dakdouk

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

We construct obfuscators of point functions with multibit output and other related functions. A point function with multibit output returns a fixed string on a single input point and zero everywhere else. Obfuscation of such functions has a useful application as a strong form of symmetric encryption which guarantees security even when the key has very low entropy: Essentially, learning information about the plaintext is paramount to finding the key via exhaustive search on the key space. Although the constructions appear to be simple and modular, their analysis turns out to be quite intricate. In particular, we uncover some weaknesses in the current definitions of obfuscation. One weakness is that current definitions do not guarantee security even under very weak forms of composition. We thus define a notion of obfuscation that is preserved under an appropriate composition operation. The constructions can use any obfuscator of point functions under the proposed definition. Alternatively, they can use perfect one way (POW) functions with statistical indistinguishability, or with computational indistinguishability at the price of somewhat weaker security.

Original languageEnglish
Title of host publicationAdvances in Cryptology - EUROCRYPT 2008 - 27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings
Pages489-508
Number of pages20
DOIs
StatePublished - 2008
Externally publishedYes
Event27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2008 - Istanbul, Turkey
Duration: 13 Apr 200817 Apr 2008

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4965 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2008
Country/TerritoryTurkey
CityIstanbul
Period13/04/0817/04/08

Keywords

  • Composable obfuscation
  • Digital locker
  • Multibit point function obfuscation
  • Obfuscation
  • Point function obfuscation

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