I tried OpenID last month if i remember correctly, after I saw it in LiveJournal. Basically I searched for a PHP OpenID server solution and “installed” it on my server, and set up an identity for myself. I tested the identity by using it on LiveJournal comments. LiveJournal is the main website that supports OpenID, though some other sites are beginning to offer OpenID as an alternative authentication mechanism.
OpenID asserts that you own a particular URL, meaning it authenticates your identity. It does not provide trust or authorisation. It is advertised as a true decentralized authentication system, as opposed to other central authentication system like Microsoft Passport. We’ll look at how it works, and followed by all the other benefits that OpenID says it achieves.
From the user point-of-view, he accesses a web site which requires his identity. An OpenID logo is available with a textbox for him to type his OpenID identity. He submits his identity URL and his identity server login is displayed. Once he logs in using his identity server’s id/password, he is returned to the original web site and he is authenticated with the identity.
Behind the scenes, once the original web site picks up the identity URL, it accesses that URL to pick up the identity server location inside the URL’s header. The site redirects the user to the identity server site, along with the URL that the identity server is supposed to return to after authentication. The identity server takes over, authenticates the user, and redirects the user back to the URL given by the original website, along with a “key”. The user submits this key to the orignal website, and the web site verifies this with the identity server, to check if the key is valid. The original web site is then satisfied that the identity URL provided belongs to the user.
The good things about this are:
(warning: example URLs are ficitious, they may not represent actual web sites)
1. Only HTML required for identity URL.
Any web page can be your identity URL, you need not have PHP or ASP running, just HTML. This is because you just need to insert a special tag in the HTML
E.g. your identity is http://sned.blogserver.com/ where you can only put HTML pages, and you registered your OpenID with http://www.openid.net/
2. Single ID
The OpenID can be used on any site that supports OpenID, it does not require you to have an account with the site you are visiting. You do not have to sign up or remember multiple passwords. You just need one OpenID identity.
E.g. You leave comments at LiveJournal.com using you OpenID registered at http://www.openid.net/, without a livejournal account.
3. Decentralized autentication, Freedom to choose identity server
There is no central OpenID server that stores all your login information. All of it is in your identity server, which can be run by any company. Even if your identity server goes out of business, or turns evil and start charging $, you can switch to another OpenID server, but preserve your identity URL by just changing the tag in you
E.g. You identity is http://sned.blogserver.com/ and you use http://openid.microsoft.com/ as your identity server. Later you change your server to http://www.openid.net, but still use http://sned.blogserver.com/ as your identity.
Yet with all these benefits, adoption is slow. Use of OpenID is now still only seen in blog comments. This is because while OpenID can establish you own that identity, the web site has to TRUST the identity server. I can easily set up my own identity server, which authenticates myself irregardless of the id/password I use. (tried and tested). However, once a trusted network of OpenIDs is set up and used by popular web sites, it may be possible to become a widespread identity system.