In this thesis, a study of information security techniques by applying certificated-based key is proposed. Nowadays, messages are sent with each other in a public communication channel widely. In exchangeability messages, to encrypt messages are necessary by using a certified-based key can be authenticated for keeping the messages secret. Thus, the certified-based key achieves messages security. First, a key agreement based anonymity scheme is proposed. By using Diffie-Hellman technique to share secrets before exchanging messages with each other. The secrets can be generated a session key from information composition or decomposition. The proposed scheme can effectively improve key authentication and anonymity. This thesis proposed a certificated-based public-key scheme based on bilinear pairing which is provided a convenient and secure computation environment. A protocol-specified trusted third party publishes a certificate by applying Diffie-Hellman. A user applies for a certificate based on the trusted third and the user can compute a public key of the certificate. Therefore, the third party can establish a trusted linkage with the user. When, the one of users wants to send a message with each other, he can authenticate key accuracy by using the certificate and public key from the other user and himself, respectively. The proposed scheme can achieve key authentication. Finally, this thesis proposes the security of each proposed schemes.