Provable Secure Generalized Signcryption

Abstract

Generalized signcryption which proposed by Han
is a new cryptographic primitive which can work as an en-
cryption scheme, a signature scheme or a signcryption scheme[5]. However,the security proof in their paper is uncorrect. our contribution are as following:First we give security notions for this new primitive.Secnond,we give an attack to [4] which is the first vision of [5] and propose an improved generalized signcryption scheme. Third, we give correct proofs for this new scheme.