2023-06-19 AnonCreds Specification Working Group Meeting

Owned by Stephen Curran
Last updated: Jun 19, 2023
3 min read

Summary

  • NEW ZOOM LINK!!!
  • Celebration!! AnonCreds 0.1.0 Release finalized!
  • AnonCreds Workshop Report
  • Mentorship Update
  • AnonCreds Specification: Mixing overview/flow information with cryptographic details
  • New revocation approaches
  • Open Discussion

Call Link: https://zoom.us/j/97954159540?pwd=WWk3WmQ3MVh1SXBYZGVreGl0QllGdz09

Recording: 

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
    • AnonCreds 0.1.0 Rust Implementation officially released!
    • Welcome Aritra Bhaduri a Hyperledger Mentor working on the AnonCreds Specification
      • Documenting the cryptography and aligning it with the implementation.
    • Update on the AnonCreds V2.0 Working Group
      • Last Week: How the model supports multiple underlying cryptographic signatures
      • Next Week: Presentation Data Models
  • Any updates to the Agenda?

Agenda

Open Issue

  • NEW ZOOM LINK!!!
  • Celebration!! AnonCreds 0.1.0 Release finalized!
  • AnonCreds Workshop Report
  • Mentorship Update
  • Deferred: AnonCreds Specification: To Do List
  • Deferred: AnonCreds Specification: Mixing overview/flow information with cryptographic details
  • Presentation: AnonCreds Revocation Options
    • AnonCreds v1.0 — CKS Signature with tails file
    • ALLOSAUR — Revocation Managers contacted at presentation time
    • LVVC — Linked Validity Verifiable Credential -- Revocation Manager issues a VC about the revocation state of a credential.
    • zk-SAM — Signed Accumulator Membership - publication of full revocation state
  • Open Discussion

Future Calls

To Dos:

  • Issue to talking about what AnonCreds verifies and what is left to the issuer to verify.
  • 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.

Action items