How can you trust...
"should be considered compromised"
Even if you've got the source code how can you trust:
The FW on your box?
The boot strap
The compiler? Dennis Richie demonstrated decades ago how to propagate viruses through the compiler by making the compiler recognise when it is recompiling itself and then inserting the virus. You can then remove this hack from the compiler source code and it will continue to propagate through every subsequent version of the compiler built by itself or it's descendants.
How do you trust the CPU? or any of the other HW.
Remember it isn't paranoia if the world is out to get you.