Puzzle challenge 2

This puzzle is much more tractable than the last. It doesn't require any great leap in imagination, more simply looking carefully at the program. It's still pretty cool.

This consists of a binary that takes a password and prints confirmation on whether that password was correct or not to screen. It only works on Linux x86_64, and you may have compatibility issues so I apologise if that's the case.

The idea is that you should find the password, not just force the binary to run through the branch it would have executed were you to give it the correct password.

Once you've completed the puzzle you'll know what I did. For those that can't run the puzzle on their machine, a description is provided here.