2023-12-18 AnonCreds Working Group Meeting

Owned by Stephen Curran
Last updated: Jan 05, 2024
4 min read

Summary

  • Eliminating the need for an AnonCreds JSON-LD @context 
  • Aries Issue Credential and Present Proof attachment formats
  • Open Discussion

Time: 7:00 Pacific / 16:00 Central Europe
Call Link: https://zoom.us/j/97954159540?pwd=WWk3WmQ3MVh1SXBYZGVreGl0QllGdz09

Recording:


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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:
  • Any updates to the Agenda?

Agenda

Open Issues

  • Eliminating having a special `@context` for AnonCreds
  • Aries Issue Credential / Present Proof Attachments
    • Current: Indy, JSON-LD - which do we use, or should we define another that (also) handles JWTs?
    • HackMD: https://hackmd.io/JEIOxf_ETnaX33kTIu7YJw?view
    • Outcome still to be defined.  Leading proposals:
      • Issue either:
        • With RFC 0592/0771 and add handling for an extra an proof type, or
        • With the new attachment format being proposed by Timo
      • Present either:
        • With RFC 0592/0771 for AnonCreds presentations and RFC 0510 (DIF Presentation Exchange) for JSON-LD presentations, or
        • With RFC 0510 for both AnonCreds and JSON-LD presentations
          • Extending the 0510 handling for generating/verifying AnonCreds presentations by automating the finding of AnonCreds source VCs for a presentation from DIF PE data, and creating a DIF PE Submission.
            • Challenge: I think (to be confirmed), an AnonCreds presentation requires including an AnonCreds-format presentation request. Can that be produced?  Should it be, since the verifier already has it...
        • NOTE: If an AnonCreds VC is to also have a non-AnonCreds DataIntegrityProof that also has holder binding, the AnonCreds VC MUST have an "id" field explicitly added, and hold a DID.  We can document that.
  • Chat:
    • 07:07:42     From Timo Glastra : what do you think of Manu's suggestion to make the cryptosuite values the same for all and hide the differences between the three in the encoded proof value metadata?
      07:08:38     From Timo Glastra : What about: anoncreds-vc-2023, anoncreds-vc-proof-2023, anoncreds-vp-2023
      07:16:15     From Andrew Whitehead : * issuanceDate becomes validFrom
      07:26:56     From Andrew Whitehead : "@vocab": "https://www.w3.org/ns/credentials/issuer-dependent#",
      07:31:08     From Stephen Curran : https://hackmd.io/oTUuyaLdSL6PHGQNpPB-4g?both
      07:32:46     From Timo Glastra : Instead of hardcoded flag, maybe we can make this an parameter to the create credential/presentation methods?
      07:33:04     From Timo Glastra : tbis = the hardcoded flag to switch between v1/v2
      07:35:27     From Timo Glastra : https://hackmd.io/s0qKgg5VQ6WKf5cSrH7Ygw?view
      07:37:02     From Andrew Whitehead : https://hackmd.io/mpvne7noRa-Q6PVGdkS47g?view
      07:39:30     From Andrew Whitehead : https://tinyurl.com/2xbf363q
      07:45:59     From Stephen Curran : https://docs.google.com/presentation/d/1QbB8U-6qccGb4jd47GjNAErE61AxNBa7KN7azM2LNQE/edit?usp=sharing
      07:54:10     From Timo Glastra : We were planning to use DIF PE for presentations yes
      08:00:44     From Timo Glastra : Current example for DIF PE: https://hackmd.io/atAmNhg7QyOVUI_CMsW_-w?view#Presentation-Definition
      08:01:06     From Timo Glastra : I'll add some more notes on how to convert between legacy and new format
      08:01:34     From Peter ani : Reacted to I'll add some more n... with ":thumbs-up"
      08:01:51     From Timo Glastra : I'm feeling quite opposed to hacking 0771 to issue multi-proof w3c credentials
      08:02:45     From Tim Bloomfield : I like the new format, but understand the time constraints
      08:02:49     From Golda Velez : @Timo Glastra we can get togther this week if you want
      08:02:57     From Timo Glastra : Reacted to "@Timo Glastra we can..." with :thumbs-up
      08:03:09     From Timo Glastra : yes might be good to get together and construct a plan
      08:03:14     From Golda Velez : Reacted to "yes might be good to..." with :100Percent

Future Calls

To Dos:

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


W3C AnonCreds + AFJ Demo