The KDM-CCA Security of REACT

摘要

In CT-RSA 2001, Okamoto and Pointcheval proposed a general conversion: Rapid enhanced-security asymmetric cryptosystem transform (REACT, for short), which achieves the CCA security in the random oracle from very weak building blocks and is (almost) optimal in terms of computational overload. In this paper, we consider the key-dependent message (KDM) security of REACT and prove that it can be KDM-CCA secure under exactly the same assumptions on its building blocks as those used by Okamoto and Pointcheval. When presenting our proof, we mainly adopt the deferred-analysis technique proposed in [25] and the random-oracle-splitting technique which has been used in [17,23] according to the roles of the random oracles in different phases.