A method for a base station to provide multicast broadcast services (MBSs). The method includes: obtaining an MBS authorization key (MAK); generating a number as an MBS group traffic encryption key (MGTEK); using a service credit number (SCN) to count an amount of service time or MBS content data; generating an MBS traffic key (MTK) based on at least the MAK and the MGTEK; encrypting MBS content data with the MTK; and transmitting the encrypted MBS content data to provide the MBSs.