A Black-Box Construction of a CCA2 Encryption Scheme from a Plaintext Aware Encryption Scheme.

Abstract

We present a construction of a CCA2-secure encryption scheme from a plaintext aware, weakly simulatable public key encryption scheme. The notion of plaintext aware, weakly simulatable public key encryption has been considered previously by Myers, Sergi and shelat (SCN, 2012) and natural encryption schemes such as the Damg˚ard Elgamal Scheme (Damg˚ard, Crypto, 1991) and the Cramer-Shoup Lite Scheme (Cramer and Shoup, SIAM J. Comput., 2003) were shown to satisfy these properties. Recently, Myers, Sergi and shelat (SCN, 2012) defined an extension of non-malleable CCA1 security, called cNM-CCA1, and showed how to construct a cNM-CCA1-secure encryption scheme from a plaintext aware and weakly simulatable public key encryption scheme. Our work extends and improves on this result by showing that a full CCA2-secure encryption scheme can be constructed from the same assumptions. Key words: CCA2-secure encryption, plaintext aware encryption, weakly simulatable public The basic security requirement for public key encryption schemes is Chosen Plaintext Attack (CPA) security [GM84] (also known as semantic security), which ensures security against a passive, eavesdropping