Christie Spyder X20, Руководство пользователя

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Spyder X20 HDCP Functionality (Option)
Spyder X20 User Manual 167
020-000916-01 Rev. 1 (04-2016)
When an HDCP-enabled transmitter is connected to the input, the transmitter may encrypt the contents using
HDCP before sending through the DVI/HDMI interface. HDCP Authentication can be divided into three stages.
During the first stage, the transmitter and receiver exchanges the KSVs and calculates a secret private key by
calculation done on Device Keys and a pseudo-random number generated by the transmitter's Cipher. Due to
the unique Cryptographic properties of the Device Keys, this secret-key calculated independently by the
transmitter and the X20 input should match. Based on this secret-key, another 2 Byte value will be generated by
the HDCP Cipher and this value is read b
y the transmitter and should match with the transmitter’s own
generated value. This completes the first stage of authentication.
During the second stage of HDCP authentication, X20 collects the list of KSVs of all the downstream devices
connected to the outputs and sends them to the transmitter. The maximum number of downstream devices for
connection to any transmitter is limited to 127 and maximum number of levels is 7. Each repeater (like X20)
makes up a level. The transmitter keeps a list of KSVs which are revoked. This list is also updated periodically
with the latest list from DCP, LLC through standard means. The transmitter checks list of all KSVs against this list
of revoked KSVs and if any in the list is a revoked one, transmitter does not send the encrypted content. If none
of the KSVs are in the revoked list the transmitter moves on to the third stage.
In the third stage, transmitter encrypts the Audio-Video content using HDCP Cipher using the results calculated
during the first stage of the authentication and sends through the DVI/HDMI interface. X20 input modules
decrypts this HDCP content using the results computed during the first stage of this authentication process and
passes on the video to various other stages of the video processing blocks. In case of Dual-link DVI transmitter,
each link is independently authenticated and encrypted. The X20 HDCP Cipher engine works at 200MHz to
service to the maximum DVI link speed of 165 MHz (for each link separately) at the inputs.
X20 DVI outputs, when connected, will try to authenticate with the receiver device(s) and collect the list of KSVs
and the number of levels of the downstream devices. Based on this data collected across all the connected
output devices, X20 generates a list of KSVs of all the devices connected downstream to X20 and also the
number of levels. This data will be updated to each of the input modules which is used by the input modules
during the second stage of authentication as mentioned. Figure 3. illustrates the HDCP operation in X20.
HDCP at X20 comes with certain limitations which are imposed by the HDCP specification implementation and
compliance requirements. HDCP Contents will only be available through the digital interfaces which are
supported as per the HDCP 1.4 specification (HDCP-protected interfaces), therefore in HDCP mode, all Analog
and SDI outputs in X20 will be shutdown (all Analog/SDI inputs will work as in normal mode).
X20 is an HDCP Repeater and passes along all the KSVs from all the downstream devices to the transmitter
device. X20 has the capability to handle and support the maximum possible levels of 7 and maximum supported
number of devices which is 127. The transmitter which is connected to the X20 may not have the capability to
support this many levels and number of devices and is up to the implementation of the transmitter as to the
effect on going above the limit of levels and number of devices supported by the particular device. X20 does not
have any control if transmitter chooses not to send HDCP content due to this in such situations.