Meaning of EMM – “Entitlement Management Message”, is an encrypted message that contains private conditional access information about the authority a viewer has to aquire reception for such services as cable or satellite television.
Scrambling and encryption are used in a Conditional Access System to prevent users from acquiring an unauthorized reception on their Satellite or Cable TV system. An Entitlement Control Message (ECM) contains access criteria and a scrambled key called a control word. The ECM is sent encrypted to the receiver, or Set Top Box (STB), in a customer's home. If the customer is authorized to acquire the reception, a subsystem in the receiver will decrypt the message. An EMM generator, a component in a conditional access system, is used to is send EMMs to the receiver. The generator receives commands from a subscriber management system and creates EMMs that get sent to the viewing card or to relay messages to the cable operators. The receiver knows whether or not the customer is authorized because of the authority is contained in an EMM.
Other Related Definitions:
“…If the box is authorized to receive a particular service, this information is encoded in an Entitlement Management Message (EMM) which is also sent as part of the MPEG stream. When a scrambled MPEG signal is received by a conditional access decoder, the box first checks the EMM to see if it is authorized to receive the key and decode the service. If the box is enabled, then the ECM is decoded and the public key is combined with the private key to decode the MPEG stream.”[Brad Gilmer - Broadcast Engineering]
“…The Entitlement Management Message generator is responsible for building "out of band" communications with the set top box to deliver the other half of the decryption key. Each EMM is uniquely encoded using the set top box's own key pair Ð thereby providing one to one security.” [Hewlett-Packard Development Company]
“…Entitlement management messages are private conditional access information which specify the authorization level or the services of specific decoders. They may be addressed to single decoders or groups of decoders.” [Advanced Television Systems Committee]
“…The scrambler key, called the control word must, of course, be sent to the receiver in an encrypted form as an entitlement control message (ECM). The conditional access subsystem in the receiver will then decrypt the control word only when authorized to do so. The authority to decrypt is sent to the receiver in the form of an entitlement management message or EMM.” [Embedded Software Group]
