Patent ID: 6584199
Filing Date: 2003-06-24
Classification: H04N

Abstract:
A conditional access system comprising:a resource subscriber management system for predetermining a first time period to transmit an entitlement management message (EMM) for checking whether or not a decoder in a receiving party is legal and a second time period to transmit a receive control message (RCM) for checking information on the amount used, transmitting the first and second time periods to each receiver via a satellite channel, and providing a key value for scrambling; a transmitting unit for generating a random-number from said key value and scrambling program sources of a broadcasting station before transmitting them to each receiver; a receiver for receiving the first time period and second time period and decoding said RCM and/or EMM, checking whether or not a smart card is permitted, and transmitting information on the amount used by a user registered in the smart card to said resource subscriber management system and, at the same time, for decrypting said key value and generating a random-number using the decrypted key value to reconstruct original data from scrambled data; and a power supply unit for turning on at the beginning of the first and second time periods and supplying power to said receiver during the first and second time periods.