There is captcha on login. It is here to protect the site from bots and bruteforcing. But it is annoying.
1. There is an option to replace it with
proof-of-work mining of CPU-only altcoins. It will not be a trouble to normal users for one-time confirmation but will make DDOS/bruteforcing hard and expensive for attackers making many queries.
2.
There should be an option to complete traditional captcha instead of mining if, for example, users have very weak hardware. But most users with good CPUs would better mine a bit than deal with annoying captcha.
3.
Users should be able to set POW difficulty for their login. If a user uses a weak mobile device, has strong password and does not fear bruteforce, he needs to set low difficulty. If a user wants to disable POW at all and login with captcha only, he could set difficulty, impossible for all of the modern supercomputers, and always use captcha.
3.
Mining difficulty for a specific user (not all the forum) should increase on every failed attempt by failed-login multiplier (FLM). User should also be able to set FLM themselves. Say, initial difficulty is 1 second on an average PC and FLM is 2. 2nd attempt will take 2 seconds, 8th will take a minute and 100 attempts will take 2^100 seconds - ages.
4. If user's account appears "locked" by increased POW difficulty after bruteforce, he should be able to use captcha alternative, see failed attempt list and (if wants) reset the difficulty.
5. Note that all
login attempts will give coins to the forum. Pity bruteforce attempts will give even more coins (remember FLM).
Main thread for the idea:
https://bitcointalk.org/index.php?topic=3240247.0I hope admins will take it seriously.