ters from the Ki key and the received RAND sequence and compares the received AUTN seal with the locally calculated one. If both seals are identical, the AAA server is authenticated. The mobile derives both CK and IK to generate the master key (MSK). 9) The mobile transmits the message EAP Response/EAP-Method AKA Challenge containing the RES seal in the message KE AUTH Request. 10) The ePDG entity transfers the message EAP Response/EAP-Method AKA Challenge in the AAR DIAMETER message to the AAA server, which compares the received RES seals respectively from the mobile and the HSS entity. If the two seals are identical, then the mobile is authenticated. 11) The AAA server transmits the SAR (Server-Assignment-Request) DIAMETER message to the HSS entity to register itself. 12) The HSS entity responds to the AAA server with the SAA (Server- Assignment-Answer) DIAMETER message containing the mobile profile. The AAA server verifies that Wi-Fi access is allowed. 13) The AAA server transmits to the ePDG entity the AAA DIAMETER message containing the EAP Success message, the MSK and the mobile profile. 14) The ePDG entity stores the MSK and forwards the EAP Success message into the message IKE_AUTH Response. 15) The mobile generates the message IKE AUTH Request containing in the AUTH block a seal calculated from its MSK, which allows the authentication of the first message IKE_SA_INIT. 16) The ePDG entity checks the seal and starts the S2b tunnel setup procedure described in Chapter 8. SWu Tunnel Establishment The ePDG entity responds with the message IKE AUTH Response containing in the AUTH block a seal calculated from its MSK, which enables authentication of the second message IKE_SA_INIT. The message IKE AUTH Response is also used to transfer to the mobile its configuration in the CP block (CFG_REPLY) and the final configuration of the SWu tunnel in the SA block. The mobile configuration was received from the PGW when establishing the S2b tunnel described in Chapter 8. 7.2.2. Procedure for rapid renewal of authenticati