Sunday, May 4, 2008

On the OpenID attribute exchange protocol

OpenIDImage via WikipediaThe process for new attribute creation (a 5 point list, proposed by D. Hardt) is broken. It assumes central control (or at least some barrier for me) over what can be postulated about me. My position on this is explained in The Profile Problem.

I would rather not see the openID initiative which is applauded for its decentralizing effects on Identity, become a centralized point for attribute definitions.

Luckily, (apart from the openID attribute namespace) anyone can define attributes as they see fit. But when everyone starts defining attributes, how do we make sure this still results in a usable system of exchange (where usable means no centralization of any kind is needed to take off).

Off course the openID namespace attributes will mostly be identifying attributes, which are attributes whose values are supposed to be unique for one person. However the non-identifying remainder of the set all possible attributes is much larger and possibly much more interesting in the lives of most people. So this is where most of the action will take place, between common folk.

Let's suppose that everyone gets his own namespace (or comparable mechanism) for creating whatever attributes to describe him or her self; This way, no central authority on 'official attributes' stands in the way of full self expression of the individuals describing themselves.

In order to exchange attributes meaningfully, the two parties must agree on the semantics (they must agree that the attributes, although maybe called differently by both parties, actually are one and the same thing). But if attributes can be dreamed up by anyone, how do we do that?

Basically there are two options. The first is that both parties decide that their attributes to be exchanged both conform to an externally known (official) attribute definition. The other option is to create an ad-hoc attribute just for the pairing of the two personally defined attributes, and use that as the underlying definition to agree upon. A new attribute definition will be instantiated, specifically for this one-on-one mapping. Both parties designate their attributes to be one of that kind.

It would not be unreasonable to expect well defined attribute collections for general use to
appear soon. If both parties designate their (personally defined) attributes as a known external uri, semantic matching is automatic. If not, human intervention is needed to decide, but that's nothing too dramatic. A simple instant message "Hey, your sending me this http://..../foobar property, it has value 14. What is it?" If an understanding is reached, both parties will have semantic agreement, and both attributes will be defined as being of a (newly created) special attribute which is defined purely for this one-on-one purpose.

The key point here is that all attributes that I create are in my private namespace, and that semantic matching occurs on a different layer, between each of the 2 identities involved.

In the end, each person would still have his own idiosyncratic world view defined by the attributes he makes up. These describe himself as well as other people he knows. Hidden from view are the mappings based on semantic agreements (the underlying attributes) via well known or ad-hoc attributes.

The result is decentralized attribute collections (they are personal, but allow for consensus via intermediate maps or via plain old human consensus).

Let's fast forward from here.

I can imagine that certain groups of people (say, project team members) might want to share some pretty interesting attribute sets, which are not 'standard' by any other means. The support of this kind of creativity is essential.

Quick creation of special-purpose attribute sets, and proposing those sets to others is where protocol thought should be focussed now. If I can quickly create, send out, and receive values of, self-defined attribute sets, all in a fully decentralized way, then we finally have a reason to ditch Lotus Notes forever (for which I should win the Nobel Peace Prize).

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