Design and implementation of trust authority servers for downloadable CAS

This paper presents the design and implementation of trust authority (TA) servers for a downloadable conditional access system (DCAS) that renewing conditional access client software by the on-line method through the cable television network. We design TA servers based on the distributed architecture to support moving of DCAS host between cable operators' networks or authentication proxy (AP) zones. Two types of TA servers, which are centralized TA and distributed TA, are proposed in this paper, and we verify the functions and performances of the implemented TA servers by developing a test-bed with a legacy cable headend system in a laboratory. The experimental results show that the designed TA servers successfully accomplished the goals of them.