Librairy vs model vs helper best place for authentification function ?

[eluser]Eric Barnes[/eluser]
My take on it is the db stuff can either be in the library or moved to a model. The beauty of CodeIgniter is that you can do things that may not be "recommended" but it still works just fine.

Take a look at this three part tutorial which should help you out and get you up to speed:
http://www.gregaker.net/2010/dec/06/crea..._part_one/