The weak point in HDCP was much simpler to exploit than previously imagined.
One of the unwritten rules of copy protection and digital rights management is that if it exists, it can be defeated. Blu-ray copy protection however, has been one of the harder ones to crack. Even though the HDCP master key was leaked in 2010, hardware was an issue.
When that key was leaked, Intel said that it was just one component and that anyone wishing to break the encryption using the key would have to manufacture their own microchips to make it work. Researchers at Ruhr University proved Intel wrong.
They accomplished this task using a $350 hardware setup that goes in between two HDMI cables and alters the signal being sent undetected. "The fact that we were able to achieve this in the context of a PhD thesis and using materials costing just €200 is not a ringing endorsement of the security of the current HDCP system," says Dr. Ing Tim Güneysu, the project lead.
Source: Tom's Hardware