Multicast rekeying is a demanding task with high requirements of flexibility to adapt to different operating situations and of efficiency to provide high quality of service and high access control. Previous software-only solutions addressed the efficiency requirement on the rekeying algorithm level and offered inherent flexibility. Proposed hardware architectures achieved high-efficiency rekeying by accelerating cryptographic operations, on which the rekeying process is based. However, they lacked flexibility because of their hard-wired functionality. In this paper a novel HW/SW architecture is proposed which combines the hardware efficiency with the software flexibility. Furthermore, the High Flexibility Rekeying Processor addresses the group and data source authentication, which were disregarded in previous related hardware-solutions.