A base station includes an apparatus for protecting information of a mobile station during a process of authenticating a ranging message of the mobile station that performs a handover in a wireless communication, system. In a method for encrypting a ranging response message in a base station, when a ranging request message is received from a mobile station that performs a handover, an authentication station is requested to transmit Authorization Key (AK) context of the mobile station. Validity of the ranging request message is determined using CMAC based on the AK context of the mobile station provided by the authentication station. When the ranging request message is valid, a response message to the ranging request message is encrypted. The encrypted response message is transmitted to the mobile station.