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.

 

CAS- End to end flow

 

Encryption and decryption of keys.

 

The CA system generates the Control Word (CW) for the scrambler and also generates and encrypts special CA messages, namely Entitlement Control Messages (ECMs) and Entitlement Management Messages (EMMs). These are used in conjunction with the entitlements stored on the smart card to recover the CW for descrambling the TS. ECMs are related to the program content at a given time and are used for recovering the control word. The CA sub-system in the set-top box (STB) decrypts the control word only when authorized to do so, and that authority is sent to the STB in the form of an EMM. EMMs thus gives information related to the status of the subscription, and this layered approach is fundamental to the operation of all CA systems in use today.

 

Another part of the CA system stores smart card information in a database, and a smart card management system provides it with information on smart cards that have been processed for use in the pay-media operation.

 

An interface to a Subscriber Management System (SMS)

 

The SMS contains a database of all subscribers in the pay-media network. It is capable of performing accounting operations on this data as well as issuing commands to the CA system to enable or disable services for subscribers.

 

CAS Services

 

Basically CAS are designed based on Business Model follow by broadcaster for authorizing several types of subscriptions like Interactivity, Pay Per View (PPV), Impulse Pay Per View (IPPV), Video on Demand (VoD), games, email. On line billing and Near Video on Demand (NVoD).

End-user terminals

 

 

Summary

 

CAS is an emerging technology and with the advancement of CAS, It provides content provider to do better business and on the other hand better quality and features to the user.

 

Maintained by: madhu.kapoor@hsc.com

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