Page Comparison

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AOL

Identity Provideer	Architectural Approach / Protocol	Comments
Google			Facebook	OpenID, OAuth 2.0 https://developers.google.com/accounts/docs/AuthForWebApps	Synapse currently uses OpenID to authenticate with Google.
Facebook	OAuth https://developers.facebook.com/docs/reference/dialogs/oauth/
Twitter			OAuth https://dev.twitter.com/docs/auth
Yahoo	OpenID, OAuth, and OpenID-OAuth Hybrid http://developer.yahoo.com/auth/
Flickr	Home grown: http://www.flickr.com/services/api/auth.spec.html	The authentication service is similar to that which we have recently added to the portal. Flickr's approach suggests security improvements, e.g. requiring the relying party to use an API key to identify itself.
Blogger (Google)	OAuth 2.0 https://developers.google.com/blogger/docs/2.0/developers_guide_protocol#Authorizing

It seems like the consensus is that OAuth is the way to go.

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