It would be awesome if there were some sort of Trusting-Trust-style "telomeres" encoded into the resultant binary, so that C and C' and C'' would all work identically, but C'''''''''' would suddenly produce different outputs.
And of course they should be invisible in the source after the first go.
He means taking the source code for the compiler and running it through the compiler, then taking the same source code and running it through the resulting compiler, etc. Same source, new binaries every time.
Yes. I know "Trusting trust". And the backdoor will be in the original source code, and after it has passed into the binary you get rid of it in the source.
Probably my favorite paper of all time, such a small paper yet so mind-blowing when you first discover it.