The present invention relates to a solution for handling encryption of control messages in a wireless telecommunications network. Key generation is based on sequence numbers and the present invention reduces access to core network devices for updating sequence numbers relating to network events by separating sequence number generation to different parts of the network and different types of network events. This is done by providing a solution where sequence number rollover events and handover events are separated from each other in providing input to radio resource control message encryption. Three different counters may be used for different types of events and all three may be used as input to an encryption algorithm.