You misunderstand the role of what the keys are doing here and you are playing your own fantasy of what is happening. I don't wish to be rude. You need to wipe your mind of what you think you understand, you need to forget your "four points" argument and pay attention to what is happening.

All the keys do in the HDMI chain is unlock a door and allow the data to pass through. This is not cryptologic data where the key is required to decode the data. The key is required to open the door and determine that a valid system is in place so the data can be sent. This is why the HDCP handshake continues after the process has begun and original authentication has been achieved. It way a working system can suddenly fail because the HDCP handshake that asks are you legal fails.

There is a dual process in place. There are authentication process that no one save the HDCP folks control. This process checks that there is a valid system in place. Once this is determined the process that the manufacturers do control takes place. This process involves the transmittal and receipt of audio and video data between source and sink.

Keys are not required to decode this data. Keys are required to determine that the system is legal and data transmission can be sent. It's a simple If else statement. If system=legal then date transmission = enabled else data transmission = disabled

The data is not encrypted and key required to decode it. The keys determine if a legal system and if it is allowable for data transmission to be sent. The moment the key solution = invalid or illegal data transmission stops.

The HDCP authentication is built to allow for an in-line device such as switcher or AVR. Source asks who is listening. Devices that are in the system respond. Source determines via the keys if the system is legal or kosher.

Can the source be tricked? Damned right. JAP's topology sounds like it is using such a scheme to trick the system. JAP claims they have an exemption because they are using IP protocols. Perhaps you are now beginning to understand why some of us have been so curious about their authentication scheme. You seem to understand that source and sink are supposed to control the authentication process. Once source determines that the system is legal data is permitted to pass down the pipe(s). Thus the AVR doesn't need keys to decode the audio and send a separate set of keys for the sink to use to decode the video.

When the AVR announced itself it sent its key to source announcing it as a valid repeater. The sink sent its key back to the source and announced its presence as a valid sink. The keys validate the system and a valid system sets a flag so that data transfer = true. Even as data transfer is taking place the source continues to quarry the system to check that the system chain remains valid. It's system legality that the keys determine. They are not required to decode the data. They are not cyphers without which the data cannot be read.

Alan