Let me here propose a solution to the DRM (Digital Rights Management) stuff within HDMI. The DRM scheme is called HDCP, or High-bandwidth Digital Content Protection. By solution, I mean removing the HDCP signal from HDMI. Just to be plain here, I do not believe that I have ever touched a piece of equipment with HDCP, and I am not proposing any form of copyright infringement. I am just wanting to show how someone might attack such a system.
There has been talk in the past about the great ‘Analog Hole’. This is the problem caused by certain signals not being able to be encrypted because they are not digital. Well, the entire world is analog. Look at a CRO, and you will find that digital signals are really analog.
So, let’s have a think about extracting a signal. How would I do it – and in a way that is unable to be effectively shut down?
Step 1. Buy a HDCP compliant LCD or PLASMA screen. Rather simple isn’t it. There is a bonus here. I don’t want the screen itself. I just want the electronics and the cables. Smash the LCD or Plasma if you want. That is up to you. But pull the thing apart.
Step 2. Obtain the manual for the LCD or PLASMA panel you are wanting to use. This is an optional step.
Step 3. Find the fastest FPGA chip you can find. Attach it to the horizontal and vertical lines going into the actual screen.
Step 4. Digitize this information, and process it.
Step 5. Output it as HDMI without HDCP.
Step 3 is a simple item to explain, but not easy in practice. Each pixel on the screen is activated by a row and a column signal. So, what we need to do is to record the value of each pixel about 100 times a second and record this into memory. Then when they are recorded we can do step 5 which is really trivial…