Thanks for playing, glad you had a good time!
There is an in-game way for solving the password but it's definitely one of the hardest puzzles in the game (which is poor design on my part as it's one of the first puzzles in the game) - you're actually not the only one who resorted to digging through the source code to figure it out!
In the post-jam version, I'm going to make the solution for this puzzle a bit more obvious, but for now I've added hints to all the puzzles in the game's description :) Thanks for the feedback!