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what is the significance and benefit of KSI (Key set indentifier) in LTE ?

+4 votes

While driving security keys in LTE, I stopped at KSI. I have a query what is the significance of KSI from UE and MME perspective ?

posted Jul 7, 2013 by Vimal Kumar Mishra

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1 Answer

+2 votes

LTE has improved 5 tuple UE authentication mechanism. Authentication of the UE is initiated by the serving MME through EPS NAS procedures. An EMM authentication request is sent to the UE with authentication parameters (RAND, AUTN) and the NAS Key Set Identifier (eKSI) or KSI-ASME.

The KSI-ASME is allocated by the MME and uniquely identifies the K-ASME. It is stored in the UE and serving MME together with the GUTI, if one is available, allowing the K-ASME to be cached and re-used during subsequent connections without re-authentication. A new authentication procedure must include a different KSI-ASME.

The UE responds to the MME with an authentication response, including the user response (RES) upon successful processing of the authentication challenge data. The MME then must validate the correctness of RES, and the intermediate KASME is determined after successful completion of the current EPS AKA, as agreed upon by the UE and MME. The EPS AKA mechanism is further described in 33.401, and the EPS NAS procedures used in the EPS AKA are described in 24.301.

I hope this will satisfy your needs.

answer Jul 7, 2013 by Salil Agrawal
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