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Introduction
Every Content Provider wants to ensure that payment is received in return for the program content they provide. The technical system that achieves this objective is called a Conditional Access (CA) system. In other word CAS (Conditional Access System) is for decision making when the stream should be play and when not based on end user (viewer) subscription.
CAS are to used to control the access to a service that is transmitted electronically, and to control the conditions under which access is granted. There are various reasons for implementing a CA system, such as the need to enforce payment by the end user for consumed services, to restrict access to programming in a particular geographical area because of program rights considerations or to facilitate parental control.
Essential components
CAS is design, based on business model given by content provider
Working of CA systems
Scrambling of the Transport Stream (Streamed Video). The digitized broadcasting stream, called a Transport Stream (TS), is applied to the scrambler. It contains an algorithm that is designed to minimize the likelihood of a pirate attack. The output of the scrambler is applied to the distribution medium such as cable, satellite or terrestrial, for delivery to the end user. The descrambling key is recovered from the encrypted keys within the scrambled TS by the smart card, and it is applied to a matching de-scrambling algorithm to recover the original program content.
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