A method and an apparatus are disclosed for securing authentication, authorization and accounting (AAA) protocol messages. An encryption key, a device identifier value, and verification data are received and stored at a network device. The verification data comprises in part a copy the encryption key and the device identifier value, and has been encrypted using a private key of a server. A shared secret is generated by applying a computational function to the encryption key and the device identifier value. Based on the shared secret, a first message integrity check value for a message is generated. The message, the first integrity check value, and the verification data are sent to the server. The server decrypts the verification data using the private key, extracts the encryption key and the device identifier value, and generates the same shared secret by applying the same computational function to the extracted encryption key and device identifier value. Based on this generated shared secret, a second message integrity check value is generated and compared to the received first message integrity check value.