What must the entitlement management message (EMM) receive from the CA controller for decryption?

The entitlement management message (EMM) requires the user key from the CA controller for decryption. The user key is essential because it is specifically tied to the individual user’s access rights, allowing the decryption of content that the user is entitled to receive. This process ensures that the EMM is used to authenticate the user's privileges and to decrypt the relevant information specific to that user.

While encryption key, service key, and control word may play roles in the broader context of content delivery and security, they do not directly pertain to the functionality of the EMM that specifically calls for user-level decryption. The user key is uniquely designed to enable access based on the individual user's entitlement, making it the correct choice in this context.