The Impossibility of Obfuscation with Auxiliary Input or a Universal Simulator

Abstract

In this paper we show that indistinguishability obfuscation for general circuits implies, somewhat counterintuitively, strong impossibility results for virtual black box obfuscation. In particular, it implies: - The impossibility of average-case virtual black box obfuscation with auxiliary input for any circuit family with super-polynomial pseudo-entropy (for example, many cryptographic primitives). Impossibility holds even when the auxiliary input depends only on the public circuit family, and not which circuit in the family is being obfuscated. - The impossibility of average-case virtual black box obfuscation with a universal simulator (with or without any auxiliary input) for any circuit family with super-polynomial pseudo-entropy. These bounds significantly strengthen the impossibility results of Goldwasser and Kalai (FOCS 2005). © 2014 International Association for Cryptologic Research.