How to integrate Facebook into WordPress registration/login?

Question

Here's what we hope to accomplish: a WordPress site that will allow users to register/login EITHER with Facebook OR WordPress and have the same access to posts/pages/content. From all the research thus far, this doesn't seem trivial...

Here's our requirements:

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User Registration

Facebook

• New users can connect with Facebook by clicking a button and then granting the requested permissions to our Facebook App. The permission-grant is a one-time event.
• They will have to log into Facebook if they aren’t already.
• When they connect for the first time a WordPress account will automatically be created for them. This integrates Facebook and WordPress.
• This free plugin may be a good starting point to integrate the two systems - http://wordpress.org/extend/plugins/simple-facebook-connect/
• Here’s another one that only handles the WordPress account creation based on a Facebook session. What it’s lacking is the ability to use the Facebook session to login after registration (it requries the WordPress username/password). http://wordpress.org/extend/plugins/facebook-registration-tool/

WordPress

• If the users doesn’t have a Facebook account or chooses not to connect through Facebook, they can manually create a WordPress account.
• Required fields are: username, email, password

User Login

Facebook

• If the user has already granted permissions to our Facebook App, they will be auto-logged-in if they have an active Facebook session and visit our website.
• Otherwise, the user will have to first log in to Facebook.

WordPress

• The user can choose to login with the username/password they created.

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Any words of wisdom on how we can accomplish these requirements?

Solution 1

After several trials, the best plugin for this kind of job is http://wordpress.org/extend/plugins/social-connect/ It covers not only Facebook but also Twitter, WordPress.com and Google

Here you can find some details on installing it http://giannopoulos.net/2011/12/28/how-to-add-facebooktwitteretc-authentication-on-wordpress/

Solution 2

Facebook supports OpenID.

There is an OpenId plugin for Wordpress I know nothing about.

http://wordpress.org/extend/plugins/openid/

Solution 3

Definetly https://wordpress.org/plugins/wp-facebook-login/ . Lightway and secure.