3.3.1.1 Overview

Authorization: The procedure for granting a receiver access to content from a transmitter. This procedure is required before a receiver can perform registration and access protected content.

Registration and Revalidation: Allows the transmitter to uniquely identify a receiver that is located nearby. Revalidation is the procedure for automatically reregistering a receiver with the transmitter after a certain amount of time has elapsed. Registration and revalidation are very similar, so for the purposes of this document, they will be grouped together in one category. Differences will be pointed out as necessary.

Proximity Detection: Measures the latency between the transmitter and a receiver. If the latency is short enough, then the receiver is considered to be near the transmitter. The transmitter will not send protected content to a receiver unless it is near.

License Retrieval: The procedure for sending a license to a registered Receiver when it requests content from a transmitter.

Data Transfer: Performed between a transmitter and a receiver after a license has been sent by the transmitter and enforced by the receiver. The content is encrypted and delivered using HTTP [RFC2616] or RTP [RFC3550].

License Management: For this procedure, the transmitter sends an updated license to the receiver to change the receiver's rights to a resource.

Revocation List Update: This procedure is permitted only after the registration procedure has successfully completed. The receiver asks the transmitter for an updated revocation list. This procedure can be initiated at any time after the registration procedure has occurred.

Authorization is performed after a receiver is discovered by a transmitter. Registration/revalidation is performed every 48 hours. The license retrieval and data transfer procedures occur every time a file is requested and played.

All of the procedures rely on messages--or sets of parameters--that are passed back and forth between a transmitter and a receiver. Messages are mapped to the HTTP, RTSP, and UPnP protocols. The following conceptual sections describe these procedures in further detail.

Authenticated Commands: The authenticated commands procedure allows sending cryptographically signed commands from the WMDRM: Network Devices Protocol receiver to the WMDRM: Network Devices Protocol transmitter. The authenticated commands are needed to control the PBDA hardware tuner.