2.1.1.5.2 Registration
After the physical connection is established and the receiver has confirmed that the transmitter supports the AAVT and WMDRM: Network Devices Protocol extensions, it SHOULD perform WMDRM: Network Devices Protocol registration.
During WMDRM: Network Devices Protocol registration, the receiver supplies its certificate to the transmitter for validation and for later exchanging content keys. Registration is performed using the SendRegistrationRequest and GetRegistrationResponse MTP operations as described in the Media Transfer Protocol Specification [MTP].
If SendRegistrationRequest and GetRegistrationResponse succeed, the receiver is considered to be registered. The receiver's certificate will expire 48 hours after registration. The registration procedure MUST be performed again. After the receiver is registered, it can perform WMDRM: Network Devices Protocol proximity detection. Both registration and proximity detection are required before the receiver can acquire a license for DRM-protected content to enable WMDRM: Network Devices Protocol delivery. For more information on the registration, see section 2.2.1.