Cryptology ePrint Archive: Report 2015/487

Contention in Cryptoland: Obfuscation, Leakage and UCE

Mihir Bellare, Igors Stepanovs and Stefano Tessaro

Abstract: This paper addresses the fundamental question of whether or not different, exciting primitives now being considered actually exist. We show that we, unfortunately, cannot have them all. We provide results of the form not(A) OR not(B), meaning one of the primitives A,B cannot exist. (But we don't know which.) Specifically, we show that: (1) VGBO (Virtual Grey Box Obfuscation) for all circuits, which has been conjectured to be achieved by candidate constructions, cannot co-exist with Canetti's 1997 AI-DHI (auxiliary input DH inversion) assumption, which has been used to achieve many goals including point-function obfuscation (2) iO (indistinguishability obfuscation) for all circuits cannot co-exist with KM-LR-SE (key-message leakage-resilient symmetric encryption) (3) iO cannot co-exist with hash functions that are UCE secure for computationally unpredictable split sources.

Category / Keywords: foundations / impossibility results, assumptions, obfuscation, VGBO, AI-DHI assumption, leakage, UCE

Original Publication (with minor differences): IACR-TCC-2016

Date: received 21 May 2015, last revised 3 Nov 2015

Contact author: istepano at eng ucsd edu

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Version: 20151103:223047 (All versions of this report)

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