Preventing CLT Attacks on Obfuscation with Linear Overhead

We describe a defense against zeroizing attacks on indistinguishability obfuscation (iO) over the CLT13 multilinear map construction that only causes an additive blowup in the size of the branching program. This defense even applies to the most recent extension of the attack by Coron et al. (PKC 2017), under which a much larger class of branching programs is vulnerable. To accomplish this, we describe an attack model for the current attacks on iO over CLT13 by distilling an essential common component of all previous attacks.

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