transmits the DEA DIAMETER message containing the EAP Success message and the PMK to the trusted Wi-Fi access. 11) Trusted Wi-Fi access stores the PMK and transfers the EAP Success message to the mobile. Mutual Authentication 6.3.3. Procedure for rapid renewal of authentication The rapid renewal of authentication makes it possible to avoid repeating the procedure from the authentication vector (RAND, AUTN, RES, CK', IK'). The implementation of the procedure for rapid renewal of authentication is indicated by the AAA server, during the initial authentication procedure, when it supplies the corresponding identifier. The identity of the access network must not change during the procedure for rapid renewal of authentication. If this happens, the normal authentication procedure must be carried out. The procedure for rapid renewal of the authentication is described in Figure 6.9. Trusted Wi-Fi server access EAP Request EAP-Method Identity EAP Response EAP-Method Identity EAP Response EAP-Method Identity EAP Request EAP-Method AKA' Reauthentication EAP Request EAP-Method AKA' Reauthentication EAP Response EAP-Method AKA' Reauthentication EAP Response EAP-Method AKA' Reauthentication EAP Success EAP Success Figure 6.9. Procedure for rapid renewal of authentication Wi-Fi Integration to the 4G Mobile Network Steps 1 to 3 are identical to those described for initial authentication in Figure 6.8. The private identity used by the mobile is the identifier for rapid renewal of authentication. 4) The AAA server transmits to the trusted Wi-Fi access the EAP Request/EAP-Method AKA' Reauthentication message containing a random number NOUNCE for the generation of a new PMK and a new identifier for the next authentication. This message is transmitted in a DER DIAMETER message and contains a MAC seal for the integrity check. 5) Trusted Wi-Fi access transfers the EAP Response/EAP-Method AKA' Reauthentication message to the mobile. 6) The mobile checks the integrity of the received message and acknowledges it in the EAP Response/EAP-Met