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Re: VOTE: Verifiable Claims Terminology

From: Henry Story <henry.story@bblfish.net>
Date: Sat, 11 Jun 2016 20:22:05 +0200
Cc: Dave Longley <dlongley@digitalbazaar.com>, public-credentials@w3.org
Message-Id: <CC39CE3C-4534-4E01-8C47-22F9D56C2EB0@bblfish.net>
To: Chadwick David <d.w.chadwick@kent.ac.uk>

> On 11 Jun 2016, at 19:49, David Chadwick <d.w.chadwick@kent.ac.uk> wrote:
> 
> 
> 
> On 11/06/2016 17:56, Dave Longley wrote:
>> On 06/11/2016 07:27 AM, David Chadwick wrote:
>>> 
>>> 
>>> It would appear to be so from the cat example that Dave gave (that
>>> unfortunately has been cut out of your reply), in which the cat has two
>>> different profiles but the same ID (because it refers to the same cat).
>>> I think this is the wrong design, because we have now created
>>> linkability between two separate profiles (or pseudonyms) that I might
>>> have sent to two different relying parties. By using a common ID for two
>>> different identity profiles we produce a correlation handle for the
>>> relying parties.
>> 
>> There are multiple use cases we want to support. One of them involves
>> the ability to share a common identity with multiple parties. That
>> doesn't mean that you *must* do this, it just means that you can.
> 
> The way I would model this is by having a claim that contains a unique
> correlating ID, such as a passport number claim (that when signed by a
> government authority becomes a credential). The id of a credential
> should not uniquely identify its holder as in your cat example. This
> should be explicitly ruled out of the model, so that correlation cannot
> slip in by mistake. Correlation should be a positive act, by providing a
> correlating claim/credential.

I have a feeling that in this discussion there needs to be some careful
initial work on semantics done, or else there is a danger that the group
will have to labor to re-invent the semantic web, and that could take decades.

It would be worth considering the following picture:

https://www.w3.org/2005/Incubator/webid/spec/identity/#overview

which shows how URIs denote things, directly and indirectly. (this limits
itself to HTTP(s) uris, for simplicity)

Then you can quite easily see how public keys can denote agents indirectly
via a relation ( a definite description as Bertrand Russel would have put it).
A public key cannot denote an agent directly, because it denotes a public key!

So I think what needs to be done is work on:
  - denotation/reference
  - meaning
  - description

and then the further part which is signatures of statements...

This way one does not need to make decisions about whether people use an
identity across sites, etc.. which is going to be up to each applicaiton
and use case. What is needed is just to distinguish claims, who make them
by reference to a direct identifier or a definite description.



> 
> regards
> 
> David
>> 
>> There are also cases where you should be able to have the unlinkability
>> characteristics you mention, which can be implemented in a variety of
>> different ways. I believe a layered approach will work here. I will
>> reiterate though that the trust characteristics, disincentives for
>> fraud, and infrastructure needs can be much more complicated in the
>> unlinkable use cases.
>> 
>> 
> 
Received on Saturday, 11 June 2016 18:22:38 UTC

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