Efficient Generalized Signcryption Schemes

Abstract

Generalized signcryption is a new cryptographic primitive which works as a signcryption scheme, a signature scheme and an encryption scheme as per need. Recently Ji et al. proposed a security model for certificateless generalized signcryption scheme and also proposed a scheme which they claim is secure under the proposed security model. In this paper we show that Ji et al. scheme is not existentially unforgeable against Type-I adversary and propose a simplified certificateless generalized signcryption. We also present an efficient identity based generalized signcryption scheme