Saturday, October 25, 2014

A Brief History of OpenID Connect

OpenID, which followed in the footsteps of SAML in 2005, revolutionized web authentication. Brad Fitzpatrick, the founder of LiveJournal, initiated it. The basic principle behind both OpenID and SAML is the same. Both can be used to facilitate web single sign on and cross-domain identity federation. OpenID is more community friendly, user centric, and decentralized. Yahoo added OpenID support in mid-January 2008, MySpace announced its support for OpenID in and in late July of that same year,, and Google joined the party in late October. By December 2009, there were more than 1 billion OpenID enabled accounts. It was a huge success as a web single sign on.

OpenID and OAuth 1.0 address two different concerns. OpenID is about authentication, while OAuth 1.0 is about delegated authorization. As both of these standards were gaining popularity in their respective domains, there was interest in combining them so that one can authenticate a user and also get a token to access their resources on their behalf in a single step. The Google Step 2 project is the first serious effort in this direction. It introduced an OpenID extension for OAuth, which basically takes Oauth-related parameters in the OpenID request/response itself. The same people who initiated the Google Step 2 project later brought it into the OpenID foundation.

The Google Step 2 OpenID extension for OAuth specification is available at:

OpenID has gone through two generations to date. OpenID 1.0/1.1/2.0 is the first generation, while OpenID extension for OAuth is the second. OpenID Connect is the third generation of OpenID.

Yahoo, Google, and many other OpenID Providers will discontinue their support for OpenID 2.0 by mid-2015, and they will migrate into OpenID Connect. 

Unlike OpenID extension for OAuth, OpenID Connect was built on top of OAuth. It simply introduces an identity layer on top of OAuth 2.0. This identity layer is abstracted into an ID token. An OAuth Authorization Server that supports OpenID Connect can return an ID token along with the access token itself.

OpenID Connect vs. OAuth 2.0:

OpenID Connect was ratified as a standard by its membership on February 26, 2014. OpenID Connect provides a lightweight framework for identity interactions in a RESTful manner. This was developed under the OpenID foundation, having its roots in OpenID, but OAuth 2.0 affected it tremendously.

The announcement by the OpenID Foundation regarding the launch of the OpenID Connect standard is available at:

More details and the applications of the OpenID Connect are covered in my book Advanced API Security.