Patent ID: 8750515

Claim:
A method for generating an identifier of a key, comprising: when a user equipment (UE) transfers from an evolved UMTS terrestrial radio access network (EUTRAN) to a universal terrestrial radio access network (UTRAN), a mobility management entity (MME) and the UE generating a key set identifier of a UTRAN system by mapping a key set identifier of an access security management entity key; and the MME sending a serving GPRS support node (SGSN) the key set identifier of the UTRAN system, along with a ciphering key and an integrity key of the system; wherein, the generation method of the mapping comprises: the UE and the MME directly assign the value of the key set identifier of the UTRAN system to be the sum of the value of the key set identifier of the access security management entity key and a constant which is appointed by the UE and network side; wherein when the UE transfers from the EUTRAN to the UTRAN in an idle state, after receiving a user information extraction request message sent by the UE to the SGSN, the MME generates an integrity key and a ciphering key using the key of the access security management entity, generates an identifier of the integrity key and the ciphering key, that is, a key set identifier, by mapping the key set identifier for the access security management entity, and sends the integrity key, the ciphering key and the key set identifier to the SGSN via a user information extraction response message; and the SGSN stores the ciphering key, the integrity key and the key set identifier.