Toward an easy-to-understand structure for achieving chosen ciphertext security from the decisional Diffie-Hellman asumption

Abstract

In this paper, we present a new public key encryption scheme which is proven chosen-ciphertext (CCA) secure under the decisional Diffie-Hellman (DDH) assumption. The main motivation behind this scheme is to clarify the essential mechanism for yielding CCA-security from the DDH assumption. The structure and security proof of our scheme is simple, and it is likely that even non-experts can immediately understand them with ease. We consider that our scheme is helpful for convincing a wide range of users (including developers and students who are just starting to study CCA-secure encryption) how the Cramer-Shoup cryptosystem and its variants work. © 2010 Springer-Verlag.