Weak leakage resilient extractable hash proof system and construction for weak leakage resilient CCA-secure public-key encryption

Abstract

Public-key encryption can be used in cloud systems to protect data in data sharing, identity authentication, etc. However, traditional public-key encryption does not capture the side-channel attacks. Inspired by this, the model of key-leakage attacks is formalised. However, constructing schemes in this model seems somewhat difficult and most key-leakage attacks in reality may be weak. In this paper, we consider the model of weak key-leakage attacks and focus on how to construct a weak leakage-resilient CCA-secure key encapsulation scheme. To this end, we present the new definitions of weak leakage-resilient extractable hash proofs and weak leakage-resilient partial ABO-extractable hash proofs and propose generic transformations to construct them from extractable hash proof. Then we show how to derive a weak leakage-resilient CCA-secure key encapsulation scheme based on them. We also give a concrete instantiation in a group of prime order and design an experiment to show the leakage-resilience in reality.