Originally Posted by pranay
Comming back to my question, dont the binary NVIDIA drivers satisfy this requirement.
Probably yes. But the X.Org server, the kernel, the video player all don't.
Even a binary driver (and the Nvidia driver not even is not all binary, there are interface modules that are delivered as source and compiled on the system when installed) can be modified e.g. to skip certain checks.
This is true for other systems as well, and that is why content protection has always failed until now. But recent versions like Vista have the capability to accept only signed drivers and other signed software and verify that an entire chain of sofware is untampered before working.
There is no such capability in Linux, and even if it would be added it would only be advisory in nature. For example, a banking application could verify that no trojans are present in its environment and present that information to the user to increase his trust in the program before inputting data.
For things like content protection this is less useful as it can be ripped out whenever the user likes so.