An ElGamal-like cryptosystem for enciphering large messages

In practice, we usually require two cryptosystems, an asymmetric one and a symmetric one, to encrypt a large confidential message. The asymmetric cryptosystem is used to deliver secret key SK, while the symmetric cryptosystem is used to encrypt a large confidential message with the secret key SK. In this article, we propose a simple cryptosystem which allows a large confidential message to be encrypted efficiently, Our scheme is based on the Diffle-Hellman distribution scheme, together with the ElGamal cryptosystem.