Actually, I would say that the math behind the algorithms is not the hard part (someone else already did the hard work, as you mention); the hard part about cry

Actually, I would say that the math behind the algorithms is not the hard part (someone else already did the hard work, as you mention); the hard part about crypto is learning all of the subtle ways that you can screw something up. This is the reason you should never implement your own crypto code -- by definition it will suck for a long, long time.