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Leakage-Resilient Cryptography from Puncturable Primitives and Obfuscation

February/2019, Asiacrypt 2018

CRYPTOGRAPHY

In this work, we develop a framework for building leakage-resilient cryptosystems in the bounded leakage model from puncturable primitives and indistinguishability obfuscation (iO). The major insight of our work is that various types of puncturable pseudorandom functions (PRFs) can achieve leakage resilience on an obfuscated street.

First, we build leakage-resilient weak PRFs from weak puncturable PRFs and iO, which readily imply leakage-resilient secret-key encryption. Second, we build leakage-resilient publicly evaluable PRFs (PEPRFs) from puncturable PEPRFs and iO, which readily imply leakage-resilient key encapsulation mechanism and thus public-key encryption. As a building block of independent interest, we realize puncturable PEPRFs from either newly introduced puncturable objects such as puncturable trapdoor functions and puncturable extractable hash proof systems or existing puncturable PRFs with iO. Finally, we construct the first leakage-resilient public-coin signature from selective puncturable PRFs, leakage-resilient one-way functions and iO. This settles the open problem posed by Boyle, Segev and Wichs (Eurocrypt 2011).

By further assuming the existence of lossy functions, all the above constructions achieve optimal leakage rate of 1−o(1). Such a leakage rate is not known to be achievable for weak PRFs, PEPRFs and public-coin signatures before.