use steam to login on my server

Hi @all

I have a login in my game built to store things like inventory, character position etc in a sql database via an api. I want to sell my game later on steam. is it enough if the authentication is done exclusively with the steamid (instead of username / password)? how is this usually done? i would like to use steam only for the overlay and login.

Did you find anything out on this?
I have stats stored in a SQL database and wanted to use the Steam log in/API. Would you just connect via steam and use them details to authenticate the SQL database?