Y. Zheng introduced a new type of cryptograghic primitive as "signcryption", which combines a function of digital signature scheme with a symmetric key encryption algorithm. Signcryption doesn`t only provide authenticity and confidentiality in a single step, but also give more efficient computation than the traditional "signature-then-encryption". And C. Gamage proposed a proxy-signcryption that efficiently combines a proxy signature with the signcryption. But, in the proposed signcryption schemes, one who obtains the sender`s private key can recover the original message of a signcrypted text. That is, forward secrecy is not offered by the signcryption scheme with respect to the sender`s private key. In this paper, we will propose a modified signcryption of Zheng`s signcryption and a variant of proxy-signcryption with forward secrecy.ith forward secrecy.