Design and implementation of headend servers for downloadable CAS

This paper presents the design and implementation of headend servers for a downloadable conditional access system (DCAS) that can securely transmit CA code via a bi-directional communication channel. To design DCAS headend server, we define core functions to be performed in headend and categorize them into four sections such as authentication, provisioning, personalization and key management. Using this classification, system architecture for DCAS headend and functional block for each server are designed. DCAS headend servers based on an enhanced DCAS protocol are implemented. In order to verify the stability and effectiveness of the implemented headend servers, we construct a test-bed using them and a legacy cable headend system in a laboratory. The experimental results show that the DCAS headend servers are well designed.