Patent ID: 8144877

Claim:
A user equipment for updating a key in an active state, the user equipment comprising a non-transitory computer readable medium having stored thereon computer executable instructions for implementing a plurality of units, the units comprising: a terminal key update unit configured to negotiate with an evolved NodeB (eNB) at a network side about an activation time of air-interface keys which have been updated by the eNB based on a new key K eNB , wherein the eNB is informed by a Mobility Management Entity (MME) at the network side of the new key K eNB generated during a key update procedure; wherein the key update procedure was initiated by the network side when a pre-defined condition is met; wherein the pre-defined condition comprises that the user equipment has performed one of: a handover between two eNBs, a handover within one eNB, and a inter-system handover.