This key is used on devices that create the HDMI signal
This key is used on devices that consume the HDMI signal
You only need one of the two keys, depending on whether your device creates or consumes the signal. In this application, they are both selected using the same selection vector shown below, but you don't have to do this if you don't want to. The best way to protect the keys from revocation is to give each device a unique key, or even better: let the device generate a key each time it's powered on.