Bug#1064807: [SOLVED] Just use default Debian MOK keys instead.

[RobotoSkunk Contact]

After trying and failing, I just gave up and reconfigured everything to 
use Debian's MOK keys instead, then purged and installed the 
nvidia-driver via APT again with Secure Boot enabled to make DKMS use 
the new MOK keys and it worked.

Sorry for the inconvenience.