The invention is a new protocol for securing the communication link between the Home Agent and the Mobile Node. A cipher key and an integrity key are generated at a home AAA server and are also generated independently at the Mobile Node. The two keys generated at the home AAA server are transmitted to the Home Agent to secure information packets transmitted between the Mobile Node and the Home Agent. The cipher key and integrity key are used to establish a security association used for information packet transmissions. The cipher key is used to encrypt the information packets, and the integrity key is used to ensure that the contents of the encrypted message are not altered.