2023-04-24 AnonCreds Specification Working Group Meeting

Owned by Stephen Curran
Last updated: Apr 24, 2023
4 min read

Summary

  • Update on the AnonCreds V2.0 Working Group
  • Hyperledger AnonCreds Workshop – May 31, 2023 8:00 Pacific / 17:00 Central Europe
  • IIW Recap
  • Discussion: AnonCreds in W3C VC and JWT formats
  • Checkin: anoncreds-rs implementation progress, requests
  • Open Discussion

Recording of Call: dummyfile.txt


Notices: 

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Meeting Attendees

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


Related Repositories:

Meeting Preliminaries:

  • Welcome and Introductions
  • Announcements
    • Presentation at VC-API Working Group
  • Any updates to the Agenda?

Agenda

Open Issue

  • Update on the AnonCreds V2.0 Working Group
    • Previous Meeting: ALLOSAUR Revocation
    • Next week: Revisiting the Issuance data models
  • Hyperledger AnonCreds Workshop - May 31
    • Proposed Agenda:
      • Introduction to AnonCreds and ZKPs
        • Set Context – VCs, issuer-holder-verifier
        • AnonCreds
        • ZKPs overview
        • Where ZKPs are used in AnonCreds
        • Exercise – issuing, holding, requesting, presenting
        • Revocation
      • AnonCreds Methods
        • AnonCreds on other than Indy Ledgers
        • Ideally an exercise using AnonCreds with other than Indy
        • What changes when using other ledgers?
      • Making AnonCreds Credential Beautiful
        • AnonCreds and the Overlays Capture Architecture (OCA)
      • Future AnonCreds Features
        • AnonCreds in W3C Format
        • AnonCreds v2.0 — what’s next?
  • IIW
    • Revocation
    • OCA
    • AnonCreds AMA
    • Lots of OpenID4VCs
    • OWF presence but no new information
  • Discussion: AnonCreds in W3C VC and JWT format
    • Importance?
      • Open discussion
        • Issue date / validity date
      • Verifiable Credential - Data Model 2.0
        • Research needed: What changes from 1.0, 1.1 to 2.0?
        • @vocab usage
    • Anyone know about the W3C to JWT transformation mechanism?
    • AnonCreds RS:
      • Consuming a credential/presentation in another format should be easy
        • Sniff the format and convert to "internal" format.
          • Receipt of Credential
          • Receipt of Presentation
      • Production of Credential/Presentation in different formats?
        • Add a parameter to indicate the type?
        • Add a call to convert the type?
        • Produce multiple formats?
      • Revocation – how to manage?
        • Not StatusList2021, how to use the "W3C Format StatusList"
    • Other questions from Discord:
      • The process of issuance in this context, more specifically, what does a AnonCreds credential request would look like in w3c format. Is the AnonCreds in W3C VC formats feature only limited to a representation of the already signed and issued credential?
      • To sign a json-ld VC you apply a signature to the Credential, transforming it into a VC without a need to communicate with the holder. With AnonCreds there is an exchange between the issuer and holder to introduce the secret link before the credential is signed.
  • Demo: IDLab AnonCreds Flows demo–very cool!  By Patrick St-Louis 
  • PRs for review and merging
  • Issues to Discuss – None.
  • Checkin: anoncreds-rs implementation progress, requests
    • Wrapping up wrappers, documentation
    • Official release coming soon!  Working in test deployments of Bifold
    • Status of ASCA-Py implementation
  • Open Discussion:

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.

Action items