There are 2 ways:
1. How about making loging into KO like loging into your bank account.
If you register you will have your account ID and main password + 30 random passwords that KO service sends to you.
If you login, then you enter your account ID and the main password. If these ones are correct and matching, then it will ask for a random password between 1-30. If you enter that right, then wohoo you can play.
2. Stop downloading keyloggers, stop sharing your account, stop making childish passwords and usernames, ..etc