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Re: VC-HTTP-API - A follow up on the RAR presentation

From: Adrian Gropper <agropper@healthurl.com>
Date: Wed, 7 Jul 2021 19:24:53 -0400
Message-ID: <CANYRo8g+dq7cgn9cBpRu_qYYrWNgjDprFsG-GpriFjfCwRydCg@mail.gmail.com>
To: W3C Credentials Community Group <public-credentials@w3.org>
Thank you Manu, Dave, and Ted for your questions. I will respond to Dave's
question below as we wait for others to chime in on the numbered issues.

Let's look at the "Vaccine Passport" use-case. It's still hot global news
and it is also an example of privacy concerns and controversies around the
W3C and the broader SSI community.

Definition: A vaccine passport (vc) is a contextual interpretation of a
vaccine credential (vp). It's a lucky coincidence that vc / vp parallels VC
/ VP :-)

1. Alice receives a vaccine for public health reasons without any
specific verification context in mind. The vc / VC is available in a
vaccine registry run by the state.

2. Alice wants to take a cruise with 1,000 strangers. The cruise operator
wants people to be safe and feel safe. For the operator, it's the only way
to stay out of bankruptcy. As a result, the operator's policy is that 100%
of anyone on board is vaccinated _and_ they have had a negative Covid test
within 72 hours. This is not an unusual context. Access to hospital
procedures, for example, also requires a recent test regardless of
vaccination status.

3. Alice gets tested at some lab 48 hours before boarding the cruise. This
allows 24 hours for the lab result and a 24 hr cushion on boarding delays
and other schedule mishaps. The test result also ends up in Alice's health
record but it is not in the state registry.

4. The cruise operator (as verifier) has contracted with a Contextual Covid
Passport Authority (CCPA, not to be confused with CCP as the passport
authority in China) to provide a Yes or No answer when Alice wants to
board.  The CCPA has some complicated method of considering the context
(2), the vc in the state registry (1), and the test in Alice's health
record (3). But it works well enough for all the parties involved.

5. To process for the Yes / No boarding determination, access will be
needed to a VC from the state registry and another VC from the hospital
that holds Alice's health records.  The Yes / No boarding determination
itself is a third VC issued to Alice 24 hours before boarding along with or
integrated into her traditional boarding pass. This is useful because
nobody wants Alice to discover a problem as she's trying to step off the

6. All three of these VCs from three separate issuers are available via
VC-HTTP API. Alice hates smartphones and apps but she is willing to use
technology to provide consent. For example, when she gets a text message on
her feature phone saying: Is it OK for {this}? Reply Yes or No.

7. With GNAP, the cruise operator (trusted by Alice) fronts a GNAP
Authorization Server operated by CCPA (trusted by the cruise operator). The
cruise operator is able to send consent text messages to Alice (as in step
6) as appropriate and Alice is fine with that because she has a _voluntary_
relationship with the cruise operator. Everyone is fine with that because
the consent questions are being presented to Alice in context of something
she more-or-less understands and expects.

So, behind the scenes, we have all sorts of servers and clients and
user-agents and maybe a mandate to do it all according to zero-trust
architecture. There may be middlemen services and trusted microservice
platforms. Alice's health records could be in 5,000 different places and
her vaccine credential could be in 50 state registries. Of the 1,000 people
on board, some are children, others are demented, and a sizable number are
not citizens of the US.

Notice that trust federations are of limited help in this situation. The
context definition is entirely up to the cruise operator as verifier. No
state or federal regulations are involved except to the extent access to
the vaccination registry VC is covered by some public sector law and access
to the health record is covered by HIPAA. Postulating that 70% of the 1,000
passengers on the cruise has an Apple or Android phone, with or without
some app like Microsoft Authenticator is reasonable but I'm not sure it
helps the situation.

Finally, I'm not saying this use-case can't work with OAuth2 and client
credentials and I'm not saying that GNAP alone will fix this. What I'm
claiming is that the success of our SSI adventure depends on not tying
VC-HTTP API to OAuth2.

- Adrian

On Wed, Jul 7, 2021 at 4:11 PM Ted Thibodeau Jr <tthibodeau@openlinksw.com>

> Adrian --
> This brief message is to say --
> The longer messages from Manu and Dave did a remarkable
> job of covering what I was thinking, and wording it more
> clearly than what I was drafting.
> It would (hopefully) bring me a lot closer to understanding,
> and thus to addressing, your position if you could provide
> some concrete answers and examples as they described and
> requested in their messages.
> Thanks,
> Ted
Received on Wednesday, 7 July 2021 23:25:37 UTC

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