1. https://bitcointalk.org/index.php?topic=3240247.0 - Don't make multiple threads with the same issue.

2. That idea's bad. What if I want to log in on my phone? 1 minute of CPU mining on a good computer is about 10-60 on a good phone.

Also, you'd just get people putting more cpu power behind these attacks. AND, you get that ddos isn't don't by pepole logging in right? It's just a large amount of network traffic, they're not all trying to login.

If you're gonig to try to get everyone's login data, that is mainly something that is done offline (obviously not going into specifics).