2020-02-25 Special: Rich Schemas

Owned by Richard Esplin
Mar 28, 2020
3 min read

Summary

Special meeting February 25

  • Discuss progress on Rich Schemas, and next steps

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Introductions

Attendees

Main Business

Rich Schemas Roadmap for Rich Schema MVP:

  • HIPE / RFCs (50% done)
    • Mapping and CredDefs use a single Schema only
    • Update Schema, Context and Encoding HIPEs/RFCs to match the Common format of rich schema objects
    • Mapping (Alex)
    • Cred Def (Alex)
    • Presentation Def 0.5 version (Ken and Brent)
    • Presentation (Ken and Brent)
    • Verifiable Credential (Alex)
    • Update existing HIPEs (Alex)
    • HIPEs for new objects:
  • Indy Node implementation (95% done) (Alex)
    • Make sure that @id == id (Alex)
    • json_ld validation for objects that must be json_lds
  • Indy-vdr (Andrew N)
    • need estimates
    • Prerequisite: CI / CD for indy-vdr, and integration into Indy SDK
    • Requests for every Rich Schema request
  • aries-credx / indy-credx (Andrew N. and Echo)
    • create_w3c_cred
    • sign_w3c_cred 
    • verify_presentation
    • create_presentation
    • Need estimates for all items

Milestones:

  1. Issuance of W3C credentials
  2. Presentation and verification

Technical items:

  1. State/search
    • Discussed the current logic of storing objects in ledger State (two entries: id and type:name:version)
    • type:name:version can be used for discovery functionality
    • We may consider supporting of discovery by schema attribute names (either on Ledger, on Observers or off-chain)
  2. HIPEs / RFCs
    • Agreed to reference just a single schema by a Mapping object (and hence a CredDef). This will simplify processing and will always have an explicit schema for every credentials.
      • If a CredDef or Mapping needs to use attributes from multiple Schema, it needs to create a new Schema first combining all sub-schemas
    • Agreed to have a shared common format for Schemas, Mappings and credentials:
      • Schema defines a set of attribute (as a graph object potentially)
      • Mapping uses a subset of the same attributes (as a graph potentially) following the same structure.
      • Every value in the Mapping object is a list of encoding and rank pairs.
      • Credentials has the same attributes as in Mapping
    • Agreed to implement Presentation Definition by phases:
      • Version 0.5: the same workflow as the current proof request
      • Version 0.6: more advanced one with groupings and selections
      • Version 1.0: final Presentation Definition interoperable with the community
    • There will be a Delta in protocols for Issuance and Presentation.
      • The workflow is supposed to be the same
      • The only difference is in the format of objects (to not be linked to old schema approach)
  3. JSON-LD
    • What objects supposed to be in json-ld format:
      • Context - Json / json_ld
      • Schema - json_ld
      • Encoding - json
      • Mapping - json_ld
      • CredDef - json
      • PresentationDef - json_ld
    • Every JSON-LD is supposed to have
      • @id
      • @type
    • @id must be equal to the Rich Schema's ID (DID).
    • The only thing that we currently expect from json-ld processing is substitution of attributes by a fully-qualified ones
    • Due to the proposed format of Schemas, Mappings and Credentials, it looks like we don't need to do any JSON-LD processing/substitution during issuance
    • We may need to do JSON-LD processing/substitution during presentation
    • If we do JSON-LD processing/substitution, then for MVP we may assume that we resolve the contexts (substitute the fields belonging to a context) belonging to the current ledger only. We are not going to resolve other Indy ledger's context, other blockchain's contexts, and Internet contexts.
  4. DID as ID
    • We considered 6 options on how ID may look like:
      • UUID
      • did:sov:const_idstring?name=...;version=....
      • did:sov:issuer_idstr?name=...;version=....
      • did:sov:context-hash-based-idstring
      • sch:sov:idstring
      • dri:sov:idstring
    • We think that we should go with did:sov:context-hash-based-idstring and the proposed Draft for canonicalization
    • We agree to postpone DID_DOC resolving of Rich Schema object (we may decide not to do it at all)
    • The question whether it's OK to use a DID for Rich Schema objects identification is raised in Community
  5. Old VS new credentials

Anoncreds 1.0Anoncreds 2.0
Old Schema == old credentials0 (already done)2? (second priority if there is a need from product point)
Rich Schema == W3C credentials1 (first prioarity)2 (second priority)

So, schema/credentials and Anoncreds version are two separate independent dimensions.

  1. The list of tasks in Jira for the action items we defined:
    • HIPEs/RFCs:
      • INDY-2337: Design Schema, Context, Encoding, Mapping, CredDef [Alex]
      • INDY-2347: Design W3C Credential [Alex]
      • INDY-2346: Design Presention Definition [Brent]
      • INDY-2348: Design W3C Presentation [Brent]
    • Indy Node:
      • INDY-2350: Improvements in Rich Schema commion code [Alex]
    • indy-vdr:
      • IS-1505: Support submitting of Rich Schema txns in indy-vdr [Andrew Nikitin]
      • IS-1506: Support getting Rich Schema txns in indy-vdr [Andrew Nikitin]
    • indy-credx:
      • IS-1507: Support issuance of W3C credentils in indy-credx 
      • IS-1508: Support presentation of W3C credentials in indy-credx