Implementing case-insensitive passwords with Authlogic
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I use Authlogic in my app and I want to make things more convenient for my users by ignoring capitalization when I check their passwords (similar to what [facebook does](http://www.labnol.org/internet/facebook-account-passwords/21241/))

What's the best way to implement this?

Also, how can I transition existing users to case-insensitive passwords? I.e., I assume I have to resave what is now `crypt(password)` as `crypt(password.downcase)`?