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Update on the AnonCreds V2.0 Working Group AnonCreds on Cardano - Presentation by Rodolfo Miranda AnonCreds, JSON-LD, W3C Verifiable Credentials Data Model Standard and the VCWG PRs Issues to discuss Checkin: anoncreds-rs implementation progress, requests Open Discussion

Recording of Call: dummyfile.txt

Notices:

This specification creating group operates under the Linux Foundation Community Specification License v1.0.

	Hyperledger is committed to creating a safe and welcoming community for all. For more information please visit the Hyperledger Code of Conduct.

Meeting Attendees

Stephen Curran (BC Gov / Cloud Compass Computing Inc.) <swcurran@cloudcompass.ca>

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Sam Curren (Indicio) <sam@indicio.tech>

Matteo Midena (Monokee) <matteo.midena@monokee.com>

Related Repositories:

AnonCreds Specification: https://hyperledger.github.io/anoncreds-spec/
AnonCreds Methods Registry: https://hyperledger.github.io/anoncreds-methods-registry
AnonCreds Rust Open Source Code: https://github.com/hyperledger/anoncreds-rs
- Ledger Agnostic AnonCreds Project Page: https://github.com/orgs/hyperledger/projects/16

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Update on the AnonCreds V2.0 Working Group
- The goal of AnonCreds v2.0 is to retain and extend the privacy-preserving features of AnonCreds v1.0, while improving capabilities, performance, extensibility, and security.
- Next week's meeting: Data Model proposals from Mike Lodder
AnonCreds on Cardano - Presentation by Rodolfo Miranda
- From Timo Glastra : I was wondering after your last demo. Even if it would support any did as issuerId, I think we should still limit the identifier of the anoncreds object to be specific to the cardano registry. That could for example mean prepending it with `did:cardano` or it could mean prefixing it with something like `anoncreds:cardano:<identifier>`. As otherwise we're going to have conflicts I assume with an anoncreds object having e.g. an `did:example` identifier, which should be reserved for the `did:example` method.
- Links:
- From Alex Andrei : I was talking to the side tree guys and they mentioned that using IPNS is also a good use case for anoncreds objects
Migrating to did:indy – can just happen?
- Credentials issued to old identifiers - proof request has old identifiers, either unqualified or "did:sov" – there is an equivalent "did:indy"
- Add to spec – unqualified and map them to "did:indy" automagically, or require the verifier to ask for both representations explicitly.
- Timo Glastra to do a test to see the effort is supporting all flavours on receipt of a proof request and in verifying. How painful is that to support?
- Link to Indy DID Networks repo: https://github.com/hyperledger/indy-did-networks
  - Discord: https://discord.com/channels/905194001349627914/941708981825576960/1036580808196116481
AnonCreds, JSON-LD, W3C Verifiable Credentials Data Model Standard and the VCWG
- On step further in aligning with JSON-LD – signing the hash of the @context RDF tuple WITHOUT credential data. Good idea?
- The VCWG Miami F2F – the resolution to the "Big Tent" issue.
PRs for review and merging
- AnonCreds Rust 102 – handling combinations of Revoked/Non-Revoked presentations
  - Timestamp
  - Handling of both revocable and non-revocable credentials in a single presentation in all cases (bug in older implementation).
- ANDs and ORs in the spec. are wrong – need to update the specification.
Issues to Discuss – notably, issues that are ready to be closed.
Checkin: anoncreds-rs implementation progress, requests
- NodeJs wrapper performance issue: https://github.com/hyperledger/aries-askar/issues/76
Open Discussion:
- Ideas on how to link from the specification to the cryptographic operations?
- Discussion from several weeks ago – having an intermediary collect presentations from holders and then share them with the final verifier.
  - Use Case:
    - A bus is visiting a secure site for which all visitors must present ID.
    - Site sends the bus operator a nonce.
    - The bus operator uses the nonce in a presentation request flow with each passenger.
    - Bus operator verifies all of the presentations.
    - The Bus operator forwards all of the presentations to the site for verification.
  - Questions:
    - Is there value in the use of the nonce in this way?
    - Does this alter the cryptography in any way?
    - Terms of use of the data received by the bus operator?
  - Discussion to be carried forward to next week.
- Proposal: Should we move attribute encoding into the specification and out of the hands of the issuer?
  - Approach:
    - Deprecate the inclusion of encoded values from the "sign credential" process
    - If passed, recalculate and error if they don't match the canonicalization algorithm
      - If integer or string integer - leave as is
      - Else stringify and hash
    - In presentation – recalculate on use, as needed.

Future Calls

To Dos:

Issue #137 added regarding further investigation into what happens to the issuance data flow nonce(s) by Belsy – definition completed, to be added to the spec. Stephen Curran
Issue #140 should WQL be allowed in a Presentation Request?
- WQL is supported currently in the Indy SDK, but not in the Aries Frameworks
- Should it be in the specification?
- If so, in what form. From Sam Curren — don't call it WQL if we do include it – just describe it.
- Not used and it is not clear there is a good reason to support it.
- Complicates the specification and the implementation.
- Decision:
  - Not supported in the specification – let's keep it out in this version
Revocation Interval
- Approach to determine if the holder used an acceptable RevRegistry – see this Issue comment
- Who calls the AnonCreds method to get the Revocation Registry from the ledger for verification
  - Verifier ~~or AnonCreds?~~
- To set "validation" to true/false based on the RevRegEntry timestamp in relation to the revocation interval? Presentation
- Key points:
  - 1. an RevRegEntry is “current” from the time it is written, to the time of the next RevRegEntry
  - 2. “within the interval” is based on when a RevRegEntry is “current” (see 1.), not its timestamp.
  - 3. AnonCreds or the Verifier (calling AnonCreds) should calculate “within interval” (using 2.) and mark verification true if the RevRegEntry used by the Prover is within the interval, else false.
    - Dangers:
      - False-Negatives: If a strict "timestamp used is between from, to" and not based on when a RevReg is "current" (per 2.), we will get "not verified" incorrectly.
      - False-Positives: If we don't do any checking of the timestamp and the interval, the holder could incorrectly use an old RevRegEntry.
  - 4. General point: AnonCreds should return both a summary (true/false) and if false, additional data about why it was false.
- Decision – add an optional `at_from_ts` set of entries, one per NRP, that AnonCreds can use for determining if the holder_ts is within the Presentation Request interval.
Backwards Compatibility
- PRs in (#82, #105) that seem to change public data structures – ones that are handled outside of AnonCreds and/or by two or more participants (issuer, holder, verifier)
- We want to retain compatibility with existing data – credentials that have been issued and the published AnonCreds objects on which they rely.
- That extends to business logic – e.g. the handling of the objects not just by AnonCreds, AnonCreds Methods and Aries Frameworks, but also by business applications built on Aries.
- Suggestion:
  - Include in the specification a statement about backward compatibility
    - Perhaps this is what Ankur had planned to do?
  - Formalize what data structures will be expected by AnonCreds
    - This is being done throughout the specification and verified against the current implementation.
  - As needed support sending and receiving data in "old" and "new" formats, but (for now) always sending "old" formats.
    - TBD if there are any such cases.

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