Login to Stackoverflow.com supports OpenID authentication.  Alternatively, we can login using using Google account (among others).Once we associate any supported account, an openID is associated with SO. How to get password of this associated openID?  Currently I use google credential to access SO, but want to use open id credential (explicitly).
How can I get the password of an openID associated site?
login;authentication;openid
You don't have an explicit OpenID credential. OpenID is a standard for authentication; the whole point of it is that you have an account from some provider, and they authenticate you for other sites. It's not that a Google account comes with some OpenID certificate; the Google account is the OpenID account.