International Journal of Computer Technology and Applications
Generalized signcryption is a new cryptographic primitive, which works as a signcryption scheme, a signature scheme and an encryption scheme as per need. It is more suitable for some storage constrained environments, e.g. smart cards, WSN (Wireless Sensor Networks) etc. Recently, Ji et al. proposed a security model for certificateless generalized signcryption scheme and also proposed a scheme, which they claim to be secure under the proposed security model. In this paper, the authors show that there security model is not complete and propose a modified security model. They also prove that Ji et al. scheme is not existentially unforgeable against Type-I adversary and propose a new efficient certificateless generalized signcryption scheme and prove the security of the proposed scheme under the new security model.