It's not a science. As tempting as it is, you can't rely purely on math to craft the perfect color palette. A systematic approach like the one described above is great to get you started, but don't be afraid to make little tweaks if you need to.

Choosing good colors for your charts is hard. This article tries to make it easier.

So let’s talk about security by obscurity. It’s a bad idea to use it as a single layer of defense. If the attacker passes it, there is nothing else to protect you. But it’s actually would be good to use it as an “additional” layer of defense. Because it has a low implementation cost and it usually works well.