two of them are straight forward. Ascend Hizi for one, Do bad things for the second one. (I'm trying to remain spoiler light here but I think everyone is aware of this at this point.)
The third one is the only hidden one and it took me a bit to figure out. You can get it about halfway through a run (or anytime after.)
Once you have the other two passwords you'll be able to see the skins/pictures you're missing and probably make a guess how to get the last one.