Authorization encompasses all mechanisms that ensure you are communicating with the expected PLC. For that purpose, SIMATIC AX supports the server authentication.
This means that the client (SIMATIC AX Tools), which connects to the server (PLC), checks the server's identity by comparing the certificate sent by the server (PLC) with a reference. SIMATIC AX uses TLS communication to achieve server-authentication via verification of the certificate provided by the PLC.