Best way to implement Single-Sign-On with all major providers?

Question

I already did a lot of research on this topic and have implemented a lot of solutions myself.

Including OpenID, Facebook Connect (using the old Rest api and the new Graph Oauth 2.0 Api), Sign in with twitter (wich has been upgraded to fully qualified Openid by now as far as I know), and so on...

But what I'm still missing is the perfect all in one solution.

During my research I stumpled about some interesting projects:

• Janrain (formerly RPX) - a commercial solution
• Gigya - a free but externally hosted solution with javascript and rest apis
• Anyopenid - a free solution for clients, commercial for websites

But I don't want to rely on an external provider and I would like a free solution as well, so I am not limited in implementation.

I have also seen developers implementing one service after another dutyfully following the providers instructinos and setting up models and database tables for everything.

Of course this will work but it is a shitload of work and always needs developement and changes in your application etc.

What I am looking for is an abstraction layer that takes all the services out there to one standard that can be integrated in my website. Once a new service appears I only want to add one model that deals with the abstraction of that specific provider so I can seamlessly integrate it into my application.

Or better, find an already existing solution that I can just dowonload.

Ideally this abstraction service would be hosted independently from my application so it can be used for several applications and be upgraded independently.

The last of the 3 solutions above looks promising from the concept. Everything is just ported to an synthetic openid, and the website jut has to implement openid.

After a while i found Django socialauth, a python based authentication system for the Django Webframework. But it looks like it operates as described above and i think this is the same login system that Stackoverflow uses (or at least some modified fork...).

I downloaded it and tried to set it up and to see whether it could be set up as a standalone solution but I had no luck, as I am not so into python either.

I would love a PHP based solution.

So after this long text my question precisely is:

• How would you implement SSO, any better idea than porting everything and have OpenID as basis?
• What are the pros and cons of that?
• Do you know any already existing solutions? Preferrably open source.

I hope this question is not too subjective, thanks in advance.

Answer 1

OpenID is going to be your best bet for this application. It is supported by many, providers:

• Google
• Yahoo
• MyOpenID
• AOL

The Only problem is that twitter has not implemented OpenID yet. This is probably due to the fact that they are a proprietery based company, so they wanted their 'own' solution.

To solve that solution, you might write a wrapper class to provide compatibility with OpenID, but the chance is that even if your users don't have a twitter account, they might have a Facebook, Google, or Yahoo account.

Facebook Supports oauth, so you will have to port oauth to OpenID

Some PHP libraries for OpenID can be found here.

Now, some questions have been raised about facebook being an oauth provider.

Their oauth URL is "https://graph.facebook.com/oauth/authorize"

If you still do not belive me, then you can look at this javascript file, where I got that URL. If you don't believe that javascript file, then notice that it is hosted by stackexchange, the provider of this site. Now you must beleive that.