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Summary

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

Meeting Attendees

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

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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 
• 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.

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• 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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