This is the part of HN I really like. People who can look at random C code working with memory and be like "yep this looks like modified X". Pretty amazing (to someone like me who mostly works in high level languages).
With the phrasing of the article, I immediately thought it must have been something simple/dumb. I quickly thought MD5 so I looked at the magic numbers in the C code and looked them up on wikipedia. Then I noticed the four F G H I functions. Still I’m not sure it is (maybe it’s something common in hashes?) and I still don’t know what the change is
"dxil.dll is closed-source, so we cannot simply patch it in the same way. To fix
this, we outright disable runtime loading of dxil.dll and silence warnings related
to it not being present / the final binary not being code signed. Instead, once
the compiler would emit a compiled shader blob, we perform our own code signing
algorithm (Mach Siegbert Vogt DXCSA) which results in a bitwise identical compiled
shader, and thus dxil.dll is no longer needed to perform code signing of shaders."
