Node.js A Good authentication module ? or whats the proper way to authenticate users?

I'm learning Node.js and looking forward to create a simple web application which will be based on Express and I was thinking of something like creating user groups and each group has its own users and each group has its own permissions (Just like ACL in Cakephp)

So can anyone recommend a good module or whatever to do so ?

Also I'm a little curious about security and how these passwords are going to be saved and what type of encryption the passwords will be encrypted in.

Well, This can be done manually but it will take sometime. The best approach I found is to create a role for each user and there will be the group ID so later we can assign the appropriate permissions

Thanks :)