OpenID Delegation: Why and How

2009-06-16

The great promise of the OpenID specification is that it can simplify identity management on the 'net. At its best, OpenID provides three great features:

Unified Identity

A single account (identity) with which you can log in to many sites, removing the need to create and remember a separate username/login for every web site you interact with.

Openness

A decentralized authentication system with multiple providers. This means that you can choose a provider (or even a few) from the many options available to vouch for your identity, and switch providers if you find a better one. Or you can even be your own provider.

Delegation

I think Delegation is the most attractive feature of OpenID because it means your own web site can act as your identity, while delegating the authentication process to one (or more) OpenID providers.

In short, with delegation you can log in to sites using a URL you own like jamesmurty.com, while taking advantage of the strong authentication options offered by providers such as Verisign's PIP. Although my Verisign PIP identity happens to be jmurty.pip.verisignlabs.com, I can use my own web site as an alias for this provider-specific identity.

By decoupling your identity from your OpenID provider you can take advantage of the fact there are many providers and easily switch providers later on without losing your identity, and without having to update your associated OpenID identity on every web site. After all, if you had to do that you might as well have created your own username/password on every site in the first place.

But...

Unfortunately, the complexity of OpenID and the challenge ordinary people can have getting it to work properly is preventing widespread adoption of the system in general, and of the Openness and Delegation features in particular. Although big players like Google and Yahoo are supporting (parts of) the specification, they are understandably encouraging people to adopt their branded OpenID identities rather than extolling the advantages of controlling your own identity.

After all, every web company would love to take on the "burden" of managing your unified web identity. It's the ultimate in vendor lock-in.

Setup OpenID delegation for your web site

If you have your own web site or blog and are able to edit the HTML pages directly, you can set up delegation by adding special link tags to the head section of one of your site's pages. You will most likely want to do this on the site's home page so you can use a short URL like jamesmurty.com instead of jamesmurty.com/my-openid-page.html.

Below are the link tags I use on my site to delegate to my jmurty Verisign PIP identity. You will need to use your own provider-specific identity URL in your links, and the format could vary quite a lot depending on the OpenID provider you choose so check your provider's documentation. Also, I'm not sure that all OpenID providers actually support delegation, so you should research this before you sign up with a provider.

<link rel="openid.server"
      href="http://pip.verisignlabs.com/server" />
<link rel="openid.delegate"
      href="http://jmurty.pip.verisignlabs.com/" />
<link rel="openid2.provider"
      href="http://pip.verisignlabs.com/server" />
<link rel="openid2.local_id"
      href="http://jmurty.pip.verisignlabs.com/" />

It is important that these link tags be included inside a valid HTML head section in your web page, or many web sites will be unable to find your delegate settings.

More Complexity, aka Taming Blogger.com

You may have noticed that the OpenID information is provided twice, once for the original OpenID specification (openid.* tags) and again for version 2 of the spec (openid2.* tags).

I don't know why the second lot of settings is necessary, since presumably the spec is supposed to be backwards-compatible, but I have found that some sites won't work properly unless the version 2 settings are provided.

One example of version incompatibility quirks is Google's Blogger.com, which allows you to comment on blog posts after logging in with an OpenID. Prior to adding the openid2.* tags I found that although Blogger would allow me to authenticate and post comments, it would replace my delegating identity jamesmurty.com with the delegated version jmurty.pip.verisignlabs.com. This meant that the delegation was essentially useless, since anyone clicking on the nickname for my comment would end up at an empty Verisign PIP landing page instead of my own site.

I'm not sure if this is Google's fault, or a fault in the OpenID spec. Either way it was annoying having to track down and fixing this issue. It just serves as yet another example where OpenID is not quite living up to the promise of simplifying identity management.

Tags: OpenID Tips

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