Comment Re:That's nice, but... (Score 1) 419
This is actually really interesting technical problem that the Tor and Debian people have spent some time working on. In practice, with most compilers today, if you compile a program twice you get different binaries. There are a variety of reasons for this, from embedded time stamps to non-deterministic shared library reference ordering to embedding the host name of the build machine.
Here's the Debian project's wiki page on the problem that goes into much more detail:
https://wiki.debian.org/ReproducibleBuilds