	US 7,590,243 B2
	Digital media conditional access system for handling digital media content
Raynold M. Kahn, Los Angeles, Calif. (US); David D. Ha, San Gabriel, Calif. (US); Thomas H. James, Pacific Palisades, Calif. (US); and Peter M. Klauss, Torrance, Calif. (US)
Assigned to The DIRECTV Group, Inc., El Segundo, Calif. (US)
Filed on May 02, 2005, as Appl. No. 11/119,712.
Claims priority of provisional application 60/567910, filed on May 04, 2004.
Prior Publication US 2005/0249350 A1, Nov. 10, 2005
Int. Cl. H04N 7/167 (2006.01)

U.S. Cl. 380—239 [380/240]

36 Claims

1. A method for processing digital media content comprising:

obtaining, in a broadcast headend, a secret authorization key (Ka);

obtaining, in the broadcast headend, a secret encryption key (SCK) that is associated with a set-top box;

encrypting, in the broadcast headend, the authorization key (Ka) using the secret encryption key (SCK) into an authorization key message (AKM) message, wherein the same secret encryption key (SCK) is used to decrypt the encrypted authorization key (Ka) by the set-top box;

obtaining, in the broadcast headend, one or more entitlement keys (Ke);

encrypting, in the broadcast headend, the one or more entitlement keys (Ke) using the authorization key (Ka) as an encryption key into an entitlement management message (EMM);

obtaining, in the broadcast headend, one or more media content encryption keys (Kc);

encrypting, in the broadcast headend, each of the media content encryption keys (Kc) using one or more of the entitlement keys (Ke) as encryption keys into an entitlement control message (ECM);

obtaining, in the broadcast headend, digital media data content (Dc);

encrypting, in the broadcast headend, the digital media data content using the one or more media content encryption keys (Kc);

delivering, from the broadcast headend, the AKM, EMM, ECM, and encrypted digital media data content to the set-top box configured to provide digital media services with the content.