Re: Agency First

Adrian, while I too support the concept of "Agency First", I just want to
point out that, if one uses the ZKP format of a verifiable credential and
the ZKP credential exchange protocol (currently implemented in Hyperledger
Indy <https://wiki.hyperledger.org/display/indy> and moving to Hyperledger
Aries <https://wiki.hyperledger.org/display/aries> as one of the
supported credential exchange protocols), then I believe your scenario can
be executed far more simply.

   1. Alice forms a peer DID connection (e.g., an exchange of pairwise
   pseudonymous DIDs) with: a) the HIV lab, and b) the dating service. Note
   that if Alice uses ZKPs, *she will never needs to share these DIDs with
   anyone else. *With ZKP credentials, these DIDs are NOT used
   in credential issuance, only in secure communications. (What is shared is a
   blinded link secret that, like the pairwise pseudonymous DID, is never
   shared with any other connection.) So these DIDs can always remain private
   to those connections.
   2. Alice does the HIV lab test and gets back a ZKP credential from the
   lab with her results (let's assume it's negative).
   3. Alice can now use the ZKP credential to prove to the dating service
   (as a verifier) that she has an HIV lab result credential *without*
disclosing
   the result. So the dating service can mark her profile as having a current
   HIV lab result credential.
   4. When Bob and Alice meet via the dating service and form their own
   private connection by exchanging pairwise pseudonymous DIDs, Alice can now
   use the ZKP credential from the HIV lab to prove to Bob that the result is
   negative *without* having to disclose either her pairwise pseudonymous
   DID with the HIV lab or her pairwise pseudonymous DID with the dating
   service. (She can also use proofs of other ZKP credentials to do selective
   disclosure to Bob of other claims about her, e.g., that she has a job,
   college degree, mortgage, etc., without disclosing details including DIDs.)

No "authorization tokens" are involved. The proof of the ZKP credential is
the "token", and because it uses ZKP, preserving privacy gets a whole lot
simpler.

(BTW, this explanation usually begs the question, "How can Bob know that
ZKP credential from the HIV lab really belongs to Alice, i.e., couldn't she
just "borrow" someone else's credential?" It's a great question, and there
are good answers, but too much for me to go into right now.)

On Tue, Jul 2, 2019 at 6:34 PM Adrian Gropper <agropper@healthurl.com>
wrote:

> This is a fork of the Data Hubs / Aries / DIF Thread asking for a
> dedicated call in CCG to discuss whether agent endpoints should be
> specified _before_ data storage endpoints.
>
> Here's the use case and logic:
>
>    - Alice is on the dating scene and wants an anonymous HIV test.
>    - Anonymous HIV tests are good public health and often free from
>    government or non-profits.
>    - Alice has her choice of where to get the HIV test. Since cost is not
>    an issue, she will pick the one that is most private.
>    - Some of the HIV test labs will support Alice's pairwise pseudonymous
>    DID. She picks that one.
>    - Alice can pick the dating service too. Other things being equal, she
>    will pick the one that is most privacy-preserving.
>    - Alice picks a dating service that supports pairwise pseudonymous
>    DIDs.
>    - Alice does not have a personal data store or a credential wallet.
>    - Alice's test result is available directly from the lab that does the
>    test to anyone with a suitable access token. The format of the result is
>    irrelevant as long as the recipient can understand the difference between
>    Positive and Negative and a Date.
>    - Alice operates an agent that decides semi-autonomously whether Bob
>    should see her test result. The agent could be proprietary to the dating
>    service or self-sovereign to Alice. However it's implemented, the agent
>    must issue a token that the lab will accept to Bob
>    - Although Alice has separate DIDs with the lab and the dating
>    service, she could be correlated if the two DIDs point to the same agent.
>    This is a concern that would need to be mitigated for an agent or a h.ub or
>    a personal data store as endpoint in her DIDs.
>    - From Alice’s agent, Bob's client gets a pointer to the lab and the
>    DID that Alice used at the lab.
>    - Bob's client comes to the lab bearing Alice’s DID. The lab points
>    Bob’s client back to Alice’s agent to get an access token.
>    - If Bob is evil and leaks Alice’s lab and lab DID to Carol, then
>    Carol’s client will likely not be able to get an access token from Alice’s
>    agent so Alice’s HIV status will remain confidential.
>    - If Bob is evil and leaks Alice’s HIV status, it will not be direct
>    from the lab and could have been forged by Bob.
>
> This use-case is important because:
>
>    - It gives Alice market power to choose privacy-preserving service
>    providers (lab, dating service). This will drive adoption. Any service
>    provider can decide to accept a DID regardless of any other service
>    provider as long as the DID resolves to Alice's agent.
>    - Alice does not have to trust the dating service or a personal data
>    store intermediary.
>    - Alice may not need a wallet or Holder at all because no VC is issued.
>    - The data model and protocol for presenting the test result is more
>    or less irrelevant. In practice, it is not totally irrelevant because most
>    labs and services are multi-purpose and the access token will have to be
>    scoped and that implies some data model schema shared between the service
>    provider and the agent.
>
> I'm calling this "Agency First" because:
>
>    - If Alice does choose to control a personal data store, then she can
>    choose a personal data store that respects her agent. Again, the market
>    power is in Alice's hands, or
>    - If Alice chooses to control a Holder then she needs to find a lab
>    that's willing to issue a VC and a Verifier that trusts the DID method, VP,
>    etc...
>
> Adrian
>
>