Alex Deucher:
The HDMI Forum has rejected our proposal unfortunately. At this time an open source HDMI 2.1 implementation is not possible without running afoul of the HDMI Forum requirements.
The big reason for HDMI’s non-freeness is the use of on-protocol encryption. They learned from DeCSS, and the forum can’t let it happen again.
I’m sure similar requirements stop DisplayPort and DVI from going open source.
There’s two I believe, HDCP which has been around since the DVI days and only now people bothered to implement, and another form of XOR-based on the actual cable itself done with a secret key, again, its DeCSS all over again but the HDMI Forum has never promoted the secret key.
XOR on the cable is completely fine for encryption, provided the input source sends the key to the chip on the cable. That really wouldn’t be hard to implement, though it would certainly negate the intended purpose here (stopping copyright violations) since it wouldn’t prevent recording boxes. However, it would provide encryption and prevent listeners on the wire from seeing the data in transit, which should be the point here.
Cables shouldn’t be where copyright protection is enforced, that should be done at the point of sale. If you don’t trust your customers, don’t sell to them. As Gabe Newell said, piracy is a service problem, if you provide a good service at a good price, you don’t need to enforce copyright protections since it’s easier and less risky to just use your service.
