Had a look in the html. The developer encrypted it with SHA256 so the code can't be read from it. The code variable also had a false name, seems a bit paranoid but considering all these "YOU MUST DONATE" messages in the game, it's hardly surprising. I don't see the point though. Trying to copy the code is just one step away from getting around the encryption. I suppose it does slow the code from being shared.
All of the codes(light, medium, hard, platinum, diamond. Except the gallery code) does the same thing. It increases trust, corruption and some player stats. The only difference is the amount added.
Since the game is based on SugarCube, you could easily manipulate these values with the your browser like any other.
Also, the amount of trust and corruption from these cheats is not significant(diamond included). If you spend some time grinding, you should get the same result.