Conditional access system of digital cable broadcasting system and receiving system and method using the same

PURPOSE: A conditional access system of a digital cable broadcasting system and a receiving system and method using the conditional access system are provided to conditionally receive broadcast using DVS-167 or DOCSIS as an out-of-band channel transmission method. CONSTITUTION: A conditional access system includes a demultiplexer(322), an out-of-band channel signal processor(323), a conditional access processor(325), and a multiplexer(321). The demultiplexer receives broadcast data transmitted through an in-band channel and an ECM(Entitlement Control Message) including a control word from a subscriber receiver(310) and demultiplexes the broadcast data and the ECM. The out-of-band channel signal processor receives an EMM(Entitlement Management Message) transmitted through an out-of-band channel from the subscriber receiver and processes the EMM. The conditional access processor descrambles scrambled broadcast data using the EMC and EMM. The multiplexer multiplexes the descrambled broadcast data and provides the multiplexed broadcast data to the subscriber receiver.