3.3.5.3 License Retrieval Details

The transmitter MUST respond to a license request message through the following steps:

  1. After the transmitter receives the license request message, it MUST verify that the device certificate is valid and has not been revoked by following the certificate validation rules specified in the Machine Certificate Specification [XMR]. The transmitter MUST also verify that the device certificate has a security level equal to or greater than the license of the content being requested, and that the EncryptKey element value in the device certificate is set to the string "1".

  2. After that, the transmitter MUST verify that the receiver has revalidated itself within the last 48 hours and is currently registered in the transmitter's device registration database. If the device is not in the database, the transmitter MUST return the error code 107 (MUST Register) to the device. If the device has not been revalidated, the transmitter MUST return the error code 108 (MUST Revalidate) to the device.

  3. The transmitter MUST verify that the action requested by the receiver is permissible for the requested content. The only action currently supported is the "Play" action. The transmitter MUST verify that the license for the requested content allows that action.

  4. The transmitter MUST send a license response message back to the receiver that contains the following: the version number of the WMDRM: Network Devices Protocol supported by the transmitter, the CRL of the transmitter (sent only if the receiver has transmitting capabilities and the transmitter has a copy of the CRL with a higher version number), and the license. The license is XMR [XMR] based and contains the Rights ID, the serial number of the receiver, 128-bit content encryption and content integrity keys used during content transfer, and an OMAC [OMAC] of the message, which is computed using the content integrity key.

  5. A transmitter MUST check whether a receiver has transmitting capabilities by checking whether the WMDRM: Network Devices Protocol transmitter node is present in the receiver's device certificate.

If the protocol version numbers of the receiver and the transmitter are not the same, the receiver and transmitter MUST use the lowest common protocol version in subsequent messages.