Abstract: A scheme of secure message interchange based on Elliptic Curves Cryptosystem (ECC) is proposed in this paper. The digital signature and symmetric key exchange in the scheme both are established on ECC. The computational intractability of the Elliptic Curve Discrete Logarithm Problem (ECDLP) over a finite field enhances security of the scheme. Each end user in a network generates its own private key and public key. Users' certificates are signed by CA and then sent to each user to keep respectively. The message and its digital signature are encrypted to transmit in the network without disclosure. The scheme proposed here provides mutual authentication between the sender and the recipient and ensures confidentiality, integrity and nonrepudiation of the interchanged messages.