Patent ID: 7526091

Claim:
A method for transmitting control information for encryption for protecting a Multimedia Broadcast/Multicast Service (MBMS) service by a broadcast/multicast-service center (BM-SC) in a mobile communication system including at least one mobile terminal desiring to receive the MBMS service and the BM-SC for providing the MBMS service desired by the at least one mobile terminal, the method comprising the steps of: transmitting an MBMS data packet configured with control information not including encryption information for encrypting MBMS data for the MBMS service, and MBMS data encrypted based on the encryption information, when the encryption information has not been changed; and transmitting an MBMS data packet configured with control information including the encryption information for encrypting MBMS data for the MBMS service, and MBMS data encrypted based on the encryption information, when the encryption information has been changed.