RE: what do DIDs identify?

There’s a few different recent conversations related to these topics (I’ve been one of the instigators).

To help clarify the discussions and evolve them to a more precise set of terms, I’ve written the following 2 articles (plus a few others).  The content of these articles are still very much under discussion but based on a recent Rocketchat, I think we’re starting to move towards some consensus (esp. related to the concepts of Actors and Things) but it is still early.  Specific feedback is greatly appreciated.


  1.  End-to-end Path from a id (DID) to a Real-Life Something
https://hyperonomy.com/2019/01/04/the-path-from-a-id-did-to-a-real-life-something/



  1.  Hyperledger Indy/Sovrin Comprehensive Architecture Reference Model (INDY ARM)
https://hyperonomy.com/2019/01/13/hyperledger-indy-sovrin-comprehensive-architecture-reference-model-arm/



Please read the Narration and Principles section to gain a full understanding of the diagrams.

I’ll re-read the comments below and try to answer as many topics as I can.

Best regards,
Michael Herman (Toronto/Calgary/Seattle)

From: Joe Andrieu <joe@legreq.com>
Sent: January 15, 2019 2:03 AM
To: public-credentials@w3.org
Subject: Re: what do DIDs identify?

There is a lot of misperception and misunderstanding here. Two items stand out.

First, DIDs are not just strings. They are URLs. They resolve to DID Documents, either by retrieval or by construction. This is fundamental. As some have suggested, a DID that does NOT resolve to a DID Document is just another GUID, at best a URI but not a URL.

Second, this notion from Daniel Hardman <daniel.hardman@evernym.com<mailto:daniel.hardman@evernym.com>> that Carlos Bruguera <cbruguera@gmail.com<mailto:cbruguera@gmail.com>> quoted:
The common characteristic of asteroids, Mount Everest, biological species in a taxonomy, and other objects of this type is that they are shared concepts controlled by nobody. There must be one identifier for them, known to all--and that identifier should have no controller.

This is fundamentally false.

There is no unique identifier for these things. What you call Mount Everest some call Chomolungma and others call Sagarmatha.

No one controls what you call it. There is no possibility that there would be a singular DID that somehow uniquely refers to it, any more than there would be a singular name that everyone uses in all conversations.

In fact, decentralized identifiers demands a framework where literally ANYONE can refer to ANYTHING by ANY identifier it wants. Any perspective that suggests "there must be one identifier" for anything is a form of centralization and antithetical to the notion of directed identity aka pairwise identifiers.

THAT said, it may be more useful to consider "actors" in this context purely as entities capable of generating the proofs in a DID Document. For example, a secure module that is part of an engine control system could use an embedded private key to generate proofs that meet the requirements for authentication without ever revealing its internal key.

In this framing, it is perfectly reasonable to have DIDs that refer to passive actors, capable only of interrogatory responses to verify said actors' provenance aka identity. Think of it as a cryptographically secure Vehicle Identification Number (VIN).

Of course, it's a bit more interesting to think of that engine autonomously interacting with the world, making it more of an "actor" in the UML sense, an "agent" to others, but we don't need to dissect the finer nuances of these terms. What matters is that the DID controller can perform the math to prove control. And that any entity seeking to authenticate as the referent of a DID is capable of performing the math associated with authentication.

In short, the point of the bitcoin revolution that spawned DIDs is that the proof is in the math. Period. Assumptions about autonomy or humanity or keys being in the hands of a particular individual are groundless leaps of faith.

-j


On Mon, Jan 14, 2019, at 11:11 PM, Tom Jones wrote:
what's the point of a did that cannot authenticate?
It may as well be a guid
Peace ..tom


On Mon, Jan 14, 2019 at 10:09 PM Carlos Bruguera <cbruguera@gmail.com<mailto:cbruguera@gmail.com>> wrote:
Interesting topic, and thanks Daniel for putting together this perception divergence. I do think it's a relevant discussion in this early stages of conception and design of DIDs.

I'd like to share a few personal views on the matter.

The motivator for DIDs is indeed SSID, in which Actors will be at the core of the ecosystem. Yet inanimated things (even abstract "things") are also part of the world we live in, and they will inevitably have a role in digital interactions among self-sovereign entities.

I agree that a (sufficiently autonomous) "thing" can perfectly be an actor, and I don't think it's wise enough to assume that these things will always be associated to a "non-thing" that is able to "control" them (or even be legally accountable, but that's whole different subject). I see no issues with a self-driving car or a DAO having a DID or a set of DIDs with which they can interact with other entities of any kind, while being themselves "self-sovereign" in a manner of speaking. Any legal/philosophical doubts regarding this are probably outside the scope of at least the (technical) possibilities for DIDs. I think we should leave this technical possibilities open, while addressing their social implications according to each specific use case and in their corresponding layers.

Now, the problem sure comes with entities that can take no possible action within a system, in which it seems there's little point in having DIDs, yet on the other hand allowing these "things" to enjoy the resolvability of DIDs (among other properties) certainly brings more "expressive power" to DIDs, which will translate to a wider potential of applications that can be built on SSID. However, I think there's a problem with the bold part of the following statement:

The common characteristic of asteroids, Mount Everest, biological species in a taxonomy, and other objects of this type is that they are shared concepts controlled by nobody. There must be one identifier for them, known to all--and that identifier should have no controller.

Since these things certainly cannot be modeled in terms of control, then it doesn't seem possible that there is a "one (and only) identifier" for them, since who has then the right or responsibility to define the attributes and identifiers for such things? It seems to me that this is more a case for verifiable claims, since there's nothing stopping anyone to freely assert public attributes to Mount Everest or an asteroid or a biological species and publish identifiers for them according to some method. So then, upon resolving these DIDs there comes a matter of trust on the entity that created them, thus you might choose to resolve and use the "Fungi X Taxonomy according to John Doe (or Institution Y)" or a different one whose source you may trust more or less. Again, it seems we're talking either about claims or a very similar concept. I just don't see how it's possible to grant unique and final identifiers to "inanimate" things in a self-sovereign manner (i.e. without establishing central "authorities" in charge of the identification process).

Perhaps we should then expand the scope of public claims to cover the act of identifying non-actor things using DIDs, or allow public claims themselves to have DIDs that can be resolved and (in this case) interpreted as "This DID respresents Object <X>, according to Entity <Y>"... In the end, philosophically speaking, the only thing we can conventionally share about the world we interact with (and which we do not control) is our subjective representation of it.

Looking forward to read other people's opinions on the matter.

Regards,
Carlos

On Wed, Jan 2, 2019 at 10:05 AM Michael Herman (Parallelspace) <mwherman@parallelspace.net<mailto:mwherman@parallelspace.net>> wrote:

Tim, again, this is an example where I believe the term DID isn’t being used properly.



A DID is only a character-string identifier …it’s not anything more than that.  Agreed?


From: Tim Bouma <trbouma@gmail.com<mailto:trbouma@gmail.com>>
Sent: January 1, 2019 6:50 PM
To: daniel.hardman@evernym.com<mailto:daniel.hardman@evernym.com>
Cc: Michael Herman (Parallelspace) <mwherman@parallelspace.net<mailto:mwherman@parallelspace.net>>; W3C Credentials CG (Public List) <public-credentials@w3.org<mailto:public-credentials@w3.org>>
Subject: Re: what do DIDs identify?



Hi everyone,



My simplified view is that DIDs are under the control of Agents (software or hardware), which in turn can be attributed to, or held accountable by Actors (Individuals, Organizations).



Things, in my view, are just a type of Agent.



If an Agent (autonomous, friendly, or otherwise) cannot be attributed or accountable to an Actor (i.e., Principal), you have a legal, not a technical problem on your hands.



What is missing in the entity model, is the notion of Relationship. I believe this model can be simplified to Individuals, Organizations, and Relationships, the details of which can be scoped out of the technical architecture.



In the end, Agents control DIDs, for the purpose of interacting with other Agents. Agents need to be attributable to Actors if they are to be trusted in any manner.



Whether an Agent is autonomous, liable, or not (such as a car) is really a question for the legal (or trust) frameworks, not necessarily addressed by the technical architecture.



Best regards,



Tim















On Tue, 1 Jan 2019 at 20:27, Daniel Hardman <daniel.hardman@evernym.com<mailto:daniel.hardman@evernym.com>> wrote:

I can agree partly. The chassis and engine of a car is not really an actor, and the software running a self-driving car IS. But I don't think that division is particularly crisp. The harder you look at it, the muddier it becomes. Where does software end and hardware begin, if programmable chips are involved? Does the software that gathers and processes signals from sensors deserve to be thought of as part of the actor--or only the part that makes decisions?



But I totally diverge on your last sentence. Yes, the owners of a car are the ones that get sued. But that doesn't make them actors in some special sense different from the way software is an actor. Actors are just entities that make decisions. Being susceptible to lawsuit doesn't make an entity an actor; it gives them legal standing. Those are two quite different concepts.





On Tue, Jan 1, 2019 at 5:59 PM Michael Herman (Parallelspace) <mwherman@parallelspace.net<mailto:mwherman@parallelspace.net>> wrote:

RE: A self-driving car is an actor; it's just one that is owned and operated by another actor.



This is another instance of the architectural terminology problem.  The car is not an Actor.



The car is a component of the Technology/Infrastructure Layer.  …that is, the car is the nuts-and-bolts vehicle with its propulsion system (engines, motors, fuel system etc.), suspension system (tires, maglev, etc.), vision/auditory/proximity/temperature/road conditions, etc, sensors, etc, etc, etc.  The car is not an Actor …at least, not technically an Actor …until it hits someone, of course.



The Actor in this scenario is the software agent(s) in the car as well as in the vendor(s) cloud(s) that are controlling this piece of nuts-and-bolts infrastructure.  IMHO ;-)



When the car does hit someone, they don’t sue the car …they sure the Actors …the owners of the software agent(s).



Michael




From: Daniel Hardman <daniel.hardman@evernym.com<mailto:daniel.hardman@evernym.com>>
Sent: January 1, 2019 5:36 PM
To: Michael Herman (Parallelspace) <mwherman@parallelspace.net<mailto:mwherman@parallelspace.net>>
Cc: W3C Credentials CG (Public List) <public-credentials@w3.org<mailto:public-credentials@w3.org>>
Subject: Re: what do DIDs identify?



Michael:



I think what you're laying out here does describe my issue with pretty good overlap. And of course you were one of the bright minds that I spent time learning from in Basel...



With respect to the notion that a DID is just a character string: I agree with you quite strongly. However, there is an *association* between the string and certain semantics, *by definition*. This association is reflected in rules about how DIDs can be created. The semantic assumptions are so strong sometimes that they leak into our verbiage in ways we don't strictly intend. If my verbiage had such leakage, I apologize. My email was about teasing out different layers of these assumptions, because I don't think they're monolithic.



I do disagree with one aspect of your characterization: I don't think the distinction between Actor and Thing is tenable. CF the entity hierarchy in Sovrin's V1 Trust Framework; it's described here: https://github.com/hyperledger/indy-hipe/tree/master/text/0014-ssi-notation#entities. The key insight is that what distinguishes People and Organizations from Things is not whether they are capable of action (including independent action, even)--but whether they are the sort of thing that can be held legally responsible for its actions.



A self-driving car is an actor; it's just one that is owned and operated by another actor. You could imagine an AI released into the wild with no controller (e.g., I instruct an AI to rotate its keys so I can never wrest control back); it would still be a thing, but it would also be an actor.





On Tue, Jan 1, 2019 at 5:25 PM Michael Herman (Parallelspace) <mwherman@parallelspace.net<mailto:mwherman@parallelspace.net>> wrote:

  1.  RE: Such an identifier could be called an "uncontrolled DID", for example. And DIDs that make the strong assumption about control could be called "DIDs" for short, or "controlled DIDs" when clarity is needed. Or we could pick other adjective pairs.



This statement implies that a DID is a “something” …that is, a ID is something that is controlled/uncontrolled …it’s not  …it’s just a character-string identifier.  I think the referenced statement is trying to project high-level behaviour onto what is essentially a character-string behaviour.  It’s similar to the remarks I heard over and over again in Basel: e.g. “A DID can have a publicKey”.  It simply can’t …it’s only a character string.  Ditto for any higher-level adjectives/behaviours.



Scan https://hyperonomy.com/2018/12/21/decentralized-identifiers-dids-architecture-reference-model-arm/






  1.  RE: Or we could say that "DID" should only be used for the form of identifier that has strong control semantics, and that whatever the other thing is, it shouldn't be a "DID".



See above.  A DID is only a character-string identifier.



@Daniel: The root problem is an architectural terminology problem:  People insist on projecting all of the different layers of architectural functionality onto this poor character string. …it’s not fair :-)



Scan https://hyperonomy.com/2018/12/21/decentralized-identifiers-dids-architecture-reference-model-arm/




Best regards,

Michael Herman (Toronto/Calgary/Seattle)


From: Daniel Hardman <daniel.hardman@evernym.com<mailto:daniel.hardman@evernym.com>>
Sent: January 1, 2019 4:39 PM
To: W3C Credentials CG (Public List) <public-credentials@w3.org<mailto:public-credentials@w3.org>>
Subject: what do DIDs identify?



At the recent Hyperledger Global Forum in Switzerland, I had some discussions about the semantics of DIDs, and I feel like I observed a deep divide in community understanding about their intent. This causes periodic surprises and frustrations, including some that came up on the recent thread with subject "Ideas about DID explanation."



I'm going to try to contrast two divergent mental models. In reality they may not be so far apart. But I think until we see their divergence clearly, we may continue to experience mental friction when we least expect it.



1. DIDs are inherently about SSI

An inconsistently articulated but very strong assumption in this worldview is that a DID is an identifier controlled for the purpose of interaction. People, organizations, and IoT things can be behind the identifier because they are the sorts of entities for which interaction is imaginable-- but notice the "IoT" qualifier on "things": inert things cannot be DID referents. This worldview is nicely articulated by various statements in the the DID Primer and the DID Spec, such as this one: "The purpose of the DID document is to describe the public keys, authentication protocols, and service endpoints necessary to bootstrap cryptographically-verifiable interactions with the identified entity."



2. DIDs are inherently about decentralization, and SSI is just one use case

Proponents of this worldview might point to the name ("DID" = "Decentralized Identifier", not "SSI Identfier" or "Controlled Identifier") and say, "Of course we need decentralization for SSI. But we need it for other reasons, too. We should be using DIDs for lots of other stuff."



What other stuff? Well, the use cases I heard in Switzerland are pretty similar to the ones I would give for uuids: "I want a DID for every asteroid NASA discovers" or "I want a DID for {Mount Everest | each species that biologists add to the Linnaean taxonomy | each database record | flows in my ERP system | etc}". What makes these different from the classic DID use cases is that the identified item is not imagined to interact in the ways that we expect as we usually describe DID Docs. You don't set up a cryptographically secure channel over which you interact with an asteroid.



In conversations where this alternate viewpoint surfaces, I commonly hear two reactions:



Reaction A: That's not a DID use case. Use UUIDs.

Reaction B: That's a perfect DID use case. An asteroid can have an agent to facilitate digital interactions, can't it? And won't you need to talk to it (e.g., to ask its current position or to request permission to land)?



I believe neither of these reactions stands up under careful analysis, and that's why I think the topic I'm raising here is worthy of such a long email.



Here's what I think Reaction A misses: Although UUIDs are createable by anyone without central coordination, they are not resolvable. One of the wonderful properties of DIDs is that they have a defined resolution mechanism that is more decentralized than DNS, *without* requiring invisible and untrackable contextual assumptions. UUIDs lack this; you have to know to go look them up in a particular database. When people say they want a DID for asteroids, they don't just want UUID uniqueness and lack of centralized registration; they *also* want DID's resolution properties. But what they want to resolve isn't information about control, it's information about the inert object in question -- when it was first discovered, where someone can find out more, how it can be looked up on wikipedia, or dozens of other properties. (Aside: some may want another DID property as well, which is cryptographically enforced global uniqueness. UUIDs lack this property for sure. Some DID methods may lack it as well, which has been a subject of frustration on earlier threads in this group...)



This brings us to Reaction B. Proponents of this reaction would say, "You should just talk to the agent for the asteroid. No new mental model needed." But let me ask you how you think China would like it if Tibet or India registered an agent for Mount Everest. And what gives NASA or the European Space Agency the right to register (control) a DID for an asteroid that an astronomer in South Africa first observed? In other words, I think Reaction B's fatal flaw is that it thinks control is an appropriate mental model for all objects. It's not. Nobody controls a new species of mushroom that gets discovered. And nobody interacts with its agent, either. The common characteristic of asteroids, Mount Everest, biological species in a taxonomy, and other objects of this type is that they are shared concepts controlled by nobody. There must be one identifier for them, known to all--and that identifier should have no controller. Modeling them with a controller is fundamentally incorrect.



This makes me wonder if we need to be able to talk about an identifier that has the decentralized and resolvable properties of DIDs, and the pluggable methods--but that doesn't make the strong assumption that behind every DID is a control- and interaction-oriented DID Doc. Instead, it might make a lighter assumption that the DID Doc lets you discover how to learn more about an inert object.



Such an identifier could be called an "uncontrolled DID", for example. And DIDs that make the strong assumption about control could be called "DIDs" for short, or "controlled DIDs" when clarity is needed. Or we could pick other adjective pairs.



Or we could say that "DID" should only be used for the form of identifier that has strong control semantics, and that whatever the other thing is, it shouldn't be a "DID". But if we do this, we need to somehow leverage all the work we've done on DID methods and specs and documentation and implementation, without reinventing the wheel.



How would you resolve this dissonance?





--

Find me at: http://about.me/tim.bouma


--
Joe Andrieu, PMP                                                                              joe@legreq.com<mailto:joe@legreq.com>
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