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On the Non-Existence of Blockwise 2-Local PRGs with Applications to Indistinguishability Obfuscation

dc.date.accessioned2017-04-06T23:00:10Z
dc.date.accessioned2018-11-26T22:27:42Z
dc.date.available2017-04-06T23:00:10Z
dc.date.available2018-11-26T22:27:42Z
dc.date.issued2017-04-06
dc.identifier.urihttp://hdl.handle.net/1721.1/107928
dc.identifier.urihttp://repository.aust.edu.ng/xmlui/handle/1721.1/107928
dc.description.abstractLin and Tessaro (Eprint 2017/250) recently proposed indistinguishability obfuscation and functional encryption candidates and proved their security based on a standard assumption on bilinear maps and a non-standard assumption on ``Goldreich-like'' pseudorandom generators (PRG). In a nutshell, they require the existence of pseudo-random generators $G:\Sigma^n \to \{0,1\}^m$ for some $\mathsf{poly}(n)$-size alphabet $\Sigma$ where each output bit depends on at most two input alphabet symbols, and which achieve sufficiently large stretch. We show a polynomial-time attack against such generators. Our attack uses tools from the literature on two-source extractors (Chor and Goldreich, SICOMP 1988) and efficient refutation of 2-CSPs over large alphabets (Allen, O'Donnell and Witmer, FOCS 2015). Finally, we propose new ways to instantiate the Lin-Tessaro construction that do not immediately fall to our attacks. While we cannot say with any confidence that these modifications are secure, they certainly deserve further cryptanalysis.en_US
dc.format.extent12 p.en_US
dc.subjectIndistinguishability Obfuscationen_US
dc.titleOn the Non-Existence of Blockwise 2-Local PRGs with Applications to Indistinguishability Obfuscationen_US


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