My previous company made monitors, and my chinese colleague told me this rumor that some of the mainboard vendors would offer "real" or "fake" HDCP, fake meaning that you could turn the monitor mainboard into a HDCP stripper.
Now I don't know how they could offer this, and I don't know how a new HDCP key is issued when a leaked one is blacklisted. I assume the engineer just didn't care or maybe the key was already old.
HDCP is broken so thoroughly that keys don't matter any more, and revoking them would break hardware on a scale that would put the F00F bug remediation cost to shame.
Some HDMI splitters commonly sold online are reportedly capable of stripping HDCP protection. I could never verify that, so I cannot point to a specific model, but a simple search seems to confirm that.
Now I don't know how they could offer this, and I don't know how a new HDCP key is issued when a leaked one is blacklisted. I assume the engineer just didn't care or maybe the key was already old.