Where can I find documentation as to HOW XOOPS creates new users?

I am trying to import an OLD website's database into the NEW XOOPS database. We do not want to re-register all of our existing members.

I am thinking of using a script that creates a CSV file and importing it into mysql. Problem is, the existing database was poorly designed and stored the password in the open (no encryption used). I have noticed that XOOPS uses an encryption algorthim, but I cannot find WHERE it encrpts it in the source code. I need to know how it is done so I can export the old info, push it through the encryption algorithm and then load it into the XOOPS database.

Does anyone know where this is located?

Thanks