Diary with a lock

At the start of the game you may have noticed this: 

This diary is important for those who want to see all the endings of the game without having to go through all the puzzle rooms. 

FINDING THE CODE:

1. The code is in the game
2. The full code found in every ending.
3. If you find the code only give others hints on where to find it because getting the answer isn't as satisfying as finding it yourself :)