Secure Public-Key Encryption from Random Oracle Transformation

摘要

In this paper, we present a new methodology, called a random oracle (RO) transformation, for designing IND-CCA secure PKE schemes in the standard model from schemes in the RO model. Unlike the RO methodology 3, 19, the security of the original scheme in the RO model does not necessarily have to be identical with that of the scheme resulting from the RO transformation. We then introduce a new notion, IND-INS-CCA security, and show how to obtain IND-CCA secure PKE schemes by instantiating Ros in IND-INS-CCA secure PKE schemes. Furthermore, we introduce another new notion, a strong pseudorandom function (PRF) family associated with a trapdoor one-way permutation generator G (briefly, G-SPRF family), which can be regarded as an enhanced PRF family, so that the resulting PKE scheme becomes quite practical. Key words: Public-key encryption, Random oracle, Instantiation.