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Re: Worldview conflicts on the purpose of DID documents

From: =Drummond Reed <drummond.reed@evernym.com>
Date: Thu, 14 Dec 2017 03:27:48 -0500
Message-ID: <CAAjunnb=z6eQvskQmfFpzYxVvV2XzaH_F1yOic+2kZRhQdtrYg@mail.gmail.com>
To: Daniel Hardman <daniel.hardman@evernym.com>
Cc: Credentials Community Group <public-credentials@w3.org>
On Wed, Dec 13, 2017 at 10:45 PM, Daniel Hardman <daniel.hardman@evernym.com
> wrote:

> How is this difference in worldviews leading to specific difficulties?
>

Daniel, so far my sense is that the biggest difficulty the difference in
worldviews has been leading to is *key management* and *key description*.

With regard to key management, in the RDF/JSON-LD worldview (or what Manu
calls the "Graph-based Data Model with an Open World Assumption"
worldview), key management and description is secondary to authentication.
As Dave has said, authentication is the first priority, and as Joe
explains, there are other ways to do authentication, so cryptographic keys
are just one type of "authentication material".

In the agent worldview, key management and key description is paramount
since that's what agents use to form cryptographic trust for all types of
interactions. Authentication is just one usage of cryptographic trust. DID
documents can be used to share the "public" parts of many different
types of cryptographic
keys (see Table 1 on page 31 of NIST 800-130
<http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-130.pdf> or
sections 4.2 and 4.3 of RFC 7517
<https://tools.ietf.org/html/rfc7517#section-4.3>), so providing this
aspect of key management is a high priority.

With regard to key description, in the "Graph-based Data Model with an Open
World Assumption" worldview, the ideal (as I understand it) would be to
describe each key using an RDF graph based on an ontology for key
description.

In the agent worldview, the goal would be to keep each key description as
simple and universal as possible. Thus the "hardening" proposal of using
just three standard properties—id, type, and value— to describe any key.
The type value is a URI (or JSON-LD name) that represents a unique (and
hopefully recommended) combination of all properties of a key together with
the purpose or usage for which it is designed.

I hope this helps. The discussion has already been helpful to me. I'd like
to reply to Markus', Joe's, and Manu's replies but must get sleep now to be
ready for the next DID Spec Closure call at 10AM PT tomorrow. For anyone
who is interested, we'll continue the discussion live there.

=Drummond


>
> On Thu, Dec 14, 2017 at 12:08 AM, =Drummond Reed <
> drummond.reed@evernym.com> wrote:
>
>> The Credentials Community Group has been holding a special set of calls
>> to drive towards closure of a next "Implementer’s Draft" of the DID spec
>> <https://w3c-ccg.github.io/did-spec/>. Three calls have been held so
>> far, and two more are currently planned (this Thursday and next Thursday at
>> 10AM Pacific Time—see a separate message sent to the list for details of
>> each call).
>>
>> After the last call, I started to see that some of the major sticking
>> points are due to what I call "worldview conflicts". These are
>> disagreements that usually surface as differences about details of a spec,
>> but where the real causes are rooted in different worldviews about
>> technology—different "big pictures" that different spec contributors are
>> working from/towards.
>>
>> When this is the case, arguments that can go on for days/weeks/months
>> about the details can often be solved much faster by identifying and
>> dealing with the differences in the underlying worldviews.
>>
>> So I wanted to start a thread just for discussion of these worldview
>> conflicts. I'll start by taking a stab at articulating the worldviews as
>> I understand them:
>>
>> *THE RDF/JSON-LD WORLDVIEW*
>>
>> In this worldview, DID documents are a standard way to describe a
>> well-known subgraph of a potentially very large RDF graph of data about a
>> subject. To quote this message from Dave Longley on a github DID issues
>> thread
>> <https://github.com/w3c-ccg/did-spec/pull/36#issuecomment-351128922>:
>> "a DID document, is about establishing an independent entity and being able
>> to authenticate that certain activities/actions were performed by that
>> entity -- and to interact with that entity via services. This necessarily
>> includes specifying how that DID document can be changed." Linked Data
>> Signatures are also important in this worldview since it is the standard
>> way to sign JSON-LD documents.
>>
>> *THE AGENT WORLDVIEW*
>>
>> In this worldview, DID documents are about having an open, interoperable
>> way to discover and manage the cryptographic keys and service endpoints
>> necessary to bootstrap secure, verifiable connections, claims, and
>> interactions between agents acting on behalf of DID subjects.
>>
>> *OBSERVATIONS*
>>
>> First, obviously neither worldview is "wrong". They are just different
>> perspectives about the primary purpose of DID documents and the universes
>> into which they fit.
>>
>> Second, in the RDF/JSON-LD worldview it is important to describe the data
>> using an RDF graph model using an ontology that can live alongside other
>> ontologies. In the agent worldview the primary importance is on
>> interoperability; it is not "anti-RDF", but it wants to avoid a dependence
>> on RDF in order to make it easy to consume/transform the metadata carried
>> by DID documents into other graph models and formats.
>>
>> Thirdly, the two have different views of key management. In the
>> RDF/JSON-LD worldview the importance is on being able to authenticate an
>> interaction with the DID subject. In the agent worldview, a DID document is
>> the "public-face" (or "non-private-face") of all types of key management,
>> i.e., it is how a DID subject shares any type of key that needs to be
>> shared with another party to verify interactions, decrypt communications,
>> or do additional key negotiation.
>>
>> *QUESTIONS*
>>
>> First, it would be good to get feedback on these worldview descriptions
>> and observations from those who hold them. In other words, are the
>> descriptions accurate? Do the observations about them follow? Are there
>> other important points that are missing?
>>
>> Secondly, once we have a picture of the differences in the worldviews,
>> what solutions to DID issues can we come up with that help reconcile these
>> differences and ideally work for both worldviews?
>>
>
>
Received on Thursday, 14 December 2017 08:28:14 UTC

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