Patent ID: 8656169

Claim:
A method of security capabilities negotiation, comprising: sending, when a user equipment (UE) in an idle state moves from a non-long term evolution (non-LTE) network to a long term evolution (LTE) network, a tracking area update (TAU) request message from the UE to a mobility management entity (MME) of the LTE network, the TAU request message including security capabilities supported by the UE; obtaining, by the MME, an authentication vector-related key from the non-LTE network; selecting, by the MME, a non-access stratum (NAS) security algorithm to use in communications between the LTE network and the UE, according to the security capabilities supported by the UE; deriving, by the MME, a NAS protection key to use in the communications between the LTE network and the UE, according to the authentication vector-related key by using a key derivation method; sending, by the MME, the selected NAS security algorithm to the UE; and deriving, by the UE, a NAS protection key to use in the communications between the LTE network and the UE, according to an authentication vector-related key thereof by using a same key derivation method as the MME.