Digital identity only works if I can send some piece of data to you, such my home phone number, and you don’t think it is my car’s serial number or my dog’s birthday. So agreeing on a vocabulary between the parties in a distributed identity system is crucial, otherwise meaningful transactions are impossible. (If you think you can guess, try again with identity data from a person half way around the globe from where you are, written in a character set that you do not even recognize.)

So we decided to sit down at NetMesh and compare the vocabularies of various identity projects and standards. We picked:

• Liberty Alliance
• LDAP
• Microsoft CardSpace (aka InfoCard)
• Sxip (both V1 and V2)
• OpenID’s Simple Registration Extension
• Light-Weight Identity (LID)

Here are the results:

A Comparison of Identity Vocabularies

Mappings of these kinds are always difficult, because no two schemas ever map well, but they are nevertheless quite interesting. Enjoy!

To discuss, I created a wiki page where you can provide feedback; I’m sure we got some things wrong and missed others, so feel free to comment. We’ll update the document occasionally based on the feedback we are gettin.

Thanks in particular to members of the Identity Gang who provided feedback on an earlier draft and set us straight about some things: Ben Adida, Scott Cantor, Chuck Mortimore and Mark Wahl.