User's Manual

Mobile WiMAX RAS SPI-2213 System Description/Ed.00

(Continued)

Classification Description

(12)~(16) When the EAP authentication is completed successfully, the ACR receives the

Master Session Key (MSK) which is the prior key to provide the security and the

Provisioned Policy on each subscriber via the DEA message from the AAA server.

The ACR creates the AK from the MSK, and transmits the Key_Change_Directive

message including the created AK Context information and the Security Association

(SA) information of the MS to the RAS. In addition, the RAS relays EAP Success to

the MS by using PKMv2-EAP-Transfer.

(17)~(19) After the EAP authentication, the RAS verifies the AK key value which it has with MS,

and transmits the SA-TEK-Challenge message to the MS to notify the start of the SA

negotiation, and the MS verifies the CMAC of the SA-TEK-Challenge message,

checks the AK key value, and transmits the SA negotiation information to the RAS by

using SA-TEK-Request. The RAS transmits SA-TEK-Response including the AKID

and the SA Descriptor which is the final result of the SA negotiation to the MS.

(20)~(21) The MS requests the Traffic Encryption Key (TEK) to the RAS by using PKMv2 Key-

Request, and the RAS creates the TEK randomly and transmits it to the MS by using

the PKMv2 Key-Reply message. Then, the TEK is transmitted by being encrypted via

the Key Encryption Key (KEK).

Keys and Functions

The functions of the keys are as follows.

- MSK: creates the AK

- AK: creates the CMAC key

- KEK: encrypts the TEK

- CMAC key: provides integrity for the MAC management message

- TEK: encrypts traffics in wireless sections