Method and system for establishing enhanced air interface key

A method for establishing an enhanced air interface key, comprising:

• during a serving Radio Network Controller (RNC) relocation process, when a user equipment relocates from a legacy source RNC to a target RNC with an enhanced security capability;
• when the target RNC with an enhanced security capability cannot learn whether the user equipment supports the enhanced security capability from a relocation request sent by the source RNC, the target RNC enabling a received legacy key received from the source RNC and indicating the user equipment that the target RNC supports the enhanced security capability;
• the user equipment verifying the indicating message by using the legacy air interface key;
• the user equipment performing security protection on the message and/or data sent to the target RNC by using the legacy air interface key, and informing the target RNC the security capability of the user equipment;
• the target RNC verifying the received message from the user equipment by using the legacy security key;
• when the received message indicating that the user equipment supports the enhanced security capability, the target RNC notifying a core network to establish and enable the enhanced air interface keys at the network side and in the user equipment respectively;
• when the received message indicating that the user equipment does not support the enhanced security capability, the target RNC performing security protection on the communication by using the legacy air interface key during or after the serving RNC relocation process;
• and
• when the target RNC cannot learn from the received message from the user equipment whether the user equipment supports the enhanced security capability, the target RNC continuing to perform security protection on the communication during or after the serving RNC relocation process by using the legacy air interface key;
• wherein the message from the user equipment is a Physical Channel Reconfiguration Complete message or a Universal Terrestrial Radio Access Network (UTRAN) Mobility Information Confirm message;
• wherein the notifying the core network to establish and enable the enhanced air interface key at the network side and in the user equipment respectively comprises:
• the core network initiating an Authentication and Key Agreement (AKA) and Security Mode Command (SMC) process, or an SMC process, establishing the enhanced air interface keys at the network side and in the user equipment respectively and enabling the enhanced air interface keys to perform security protection on subsequent communication;
• wherein the target RNC enabling a received legacy key received from the source RNC and indicating the user equipment that the target RNC supports the enhanced security capability comprises:
• the target RNC storing the received legacy key, allocating resources for the user, sending a Downlink Dedicated Control Channel (DL DCCH) message, and directly using the received legacy key to perform integrity protection on the message;
• the target RNC and the core network establishing a new Iu bearing to allocate RRC connection resources and radio link resources for the user equipment;
• sending a relocation request confirm message back to the source RNC, wherein the relocation request confirm message carrying the security capability the network.