On June 13, 2010 at 11:50, Audible Solutions said...
You have no clue 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.
Thank you for this response. It does directly address the point I have been trying to make. You are correct that I have the understanding that there is a cryptologic engine here. I can see if this understanding is incorrect that my argument is flawed.
Here's where I am going to test your patience even further. I still do believe the TMDS stream is encrypted! I say this because I have read as much in numerous places including the below white paper from DCP. The excerpt shown is from page 8.
It is possible that I am misunderstanding the paper. Or that I am reading it out of context. Or that the paper is wrong.
I'd much appreciate your thoughts.
[Link: digital-cp.com]After authentication, the transmitter uses its HDCP cipher engine and the shared session key to create a stream of encrypted data that can only be decrypted by the receiver. The receiver uses its HDCP cipher engine and its copy of the session key to decrypt the content.
EDIT: a more detailed description of the HDCP TMDS encryption is on page 36 of this document from DCP. (I did not read the whole 90 page document, so perhaps I am taking this out of context.)
[Link: digital-cp.com]HDCP Encryption is applied at the input to the T.M.D.S. Encoder and decryption is applied at the out of the T.M.D.S. Decoder (Figure 3-1).
Last edited by crosen on June 13, 2010 12:14.
