{"id":780,"date":"2007-05-24T12:05:32","date_gmt":"2007-05-24T20:05:32","guid":{"rendered":"\/?p=780"},"modified":"2007-05-27T09:41:48","modified_gmt":"2007-05-27T17:41:48","slug":"ben-laurie-on-selective-disclosure-part-2","status":"publish","type":"post","link":"https:\/\/www.identityblog.com\/?p=780","title":{"rendered":"Ben Laurie on Selective Disclosure (Part 2)"},"content":{"rendered":"

In introducing people to his Selective Disclosure paper, Google's Ben Laurie says: <\/p>\n

In fact, there are many ways CardSpace could<\/em> violate the laws, but there is one which it is currently inherently incapable of satisfying, which is the 4th law – the law of directed identity – which says, once you\u00e2\u20ac\u2122ve fought your way through the jargon, that your data should not be linkable.<\/p><\/blockquote>\n

Ben doesn't like the term “omni-directional identifier”, which is certainly his prerogative.  But speaking of jargon, note that according to the Oxford English Dictionary, Ben's word “linkable” doesn't actually exist… <\/p>\n

Meanwhile “omni-directional” is a real word from the field of telecommunications (isn't that what we are working in?)  It means “of equal sensitivity or power in all directions”.  Similarly, “unidirectional” means “moving or operating in a single direction”.<\/p>\n

So I think the Fourth Law is precise enough:<\/p>\n

A universal identity system must support both omni-directional identifiers for use by public entities and unidirectional identifiers for use by private entities, thus facilitating discovery while preventing unnecessary release of correlation handles.<\/p><\/blockquote>\n

The word “discovery” is again used in the technical sense of making it possible to locate and rendezvous with other entities.   The goal here is to embrace the range of use cases I discussed in part one<\/a>. <\/p>\n

Ben argues that CardSpace breaks this Fourth Law.  In this he is wrong.  I suspect he is confusing CardSpace, which is just a way of selecting between identity providers, and the identity providers themselves.  Let's get that really straight.<\/p>\n

CardSpace is one component of the Identity Metasystem – by which I mean a distributed mesh of parties asserting and depending upon identity.  CardSpace informs the user about the identity providers that can satisfy a given relying party request, and provides a mechanism to tell the user what information must be released to the relying party in order to gain admission to the site.  But the identity selector does not itself make assertions or sign them cryptographically, or do anything that introduces linkability or traceability<\/em>.  If linkability is introduced, it is because of the choice of the identity provider people use with the the system, and of the cryptographic systems they employ.  <\/p>\n

Privacy characteristics of the self-asserted Identity Provider<\/strong> <\/p>\n

While CardSpace is an identity selector, we have built it to include<\/em> a self-asserted identity provider as a way to bootstrap the system.   So what are the privacy characteristics of this provider?<\/p>\n