I thought about writing a program, which detects the modifications of the provided driver compared to a signed driver from NVIDIA. I would guess, that not many modifications were necessary, besides changing some binary flag to lock the card down, or something along those lines.
Now, the only problem is, that I don't know which driver version from NVIDIA to compare it to. If someone finds out on which version the modified driver is based on, I could go on and try to check this.