Known Issuer Registry Client (@digitalcredentials/issuer-registry-client)

Isomorphic client for looking up DIDs in Known Issuer/Known Verifier registries. For Node, browser and React Native.

Table of Contents

• Description
• Install
• Usage
• Contribute
• License

Description

This is a client library that looks up DIDs in either:

• an OIDF registry using the /fetch?sub= oidf endpoint to lookup the did, passing it as the value of the 'sub' paramter
• a static list of DIDs encoded in a format previously used by the DCC for it's member and community registries, and served publicly, like this one: https://github.com/digitalcredentials/dcc-community-registry/registry.json

Note that an individual DID can appear in multiple registries. Because of that, the order of registries loaded matters. For example, given a registry list:

const knownRegistries = [
   {
        "type": "oidf",
        "fetchEndpoint": "https://registry.dcconsortium.org/fetch?sub=",
        "name": "DCC Member Registry"
    },
    {
      "name": "DCC Sandbox Registry",
      "url": "https://digitalcredentials.github.io/sandbox-registry/registry.json",
      "type": "dcc-legacy"
    }
]

If an issuer DID is contained in both of those registries, the issuer entry (that contains the issuer name and URL) will come from the first registry, "DCC Member Registry".

In other words, verifiers and other implementers must order the registries in order of most authoritative to least.

Install

• Node.js 18+ is recommended.

NPM

To install via NPM:

npm install @digitalcredentials/issuer-registry-client

Development

To install locally (for development):

git clone https://github.com/digitalcredentials/issuer-registry-client.git
cd issuer-registry-client
npm install

Usage

You'll need an array of known issuer and verifier registries you would like to check against, like this publicly available copy of the DCC known registries:

https://digitalcredentials.github.io/dcc-known-registries/known-did-registries.json

which as of apr 22 2025 looked like so (reproduced here for convenience):

[
    {
        "type": "oidf",
        "fetchEndpoint": "https://registry.dcconsortium.org/fetch?sub=",
        "name": "DCC Member Registry"
    },
    {
        "type": "dcc-legacy",
        "name": "DCC Sandbox Registry",
        "url": "https://digitalcredentials.github.io/sandbox-registry/registry.json"
    },
    {
        "type": "dcc-legacy",
        "name": "DCC Community Registry",
        "url": "https://digitalcredentials.github.io/community-registry/registry.json"
    },
    {
        "type": "dcc-legacy",
        "name": "MSP Registry",
        "url": "https://sandbox-issuer.myskillspocket.com/registry.json"
    }
]

You would use that list thusly:

import { RegistryClient } from '@digitalcredentials/issuer-registry-client'

const registryClient = new RegistryClient()

// get the list of known issuers from wherever you store it, which could just be in a variable,
// but here we show how to fetch the DCC's list from it's github repository:
const response = await fetch("https://digitalcredentials.github.io/dcc-known-registries/known-did-registries.json");
const knownRegistries = await response.json();

// set the registry client to use that list
await registryClient.use({ registries: knownRegistries })

// You can now query to see if a DID is known in any registry
const results = registryClient.lookupIssuersFor('did:key:z6MkpLDL3RoAoMRTwTgo3rs39ZwssfaPKtGdZw7AGRN7CK4W'))

The lookup returns:

• a list of issuers in which the provided DID is registered
• a list of any registries (from the provided known issuers list) that couldn't be checked

Each returned issuer includes metadata for the issuer and metadata for the registry in which the issuer was registered.

Here is an example lookup response for a DID that is registered in one legacy registry, one OIDF regsitry, and also lists one registry that couldn't checked for some reason (e.g., the server was down):

{
    "matchingIssuers": [
      {
        "issuer": {
          "federation_entity": {
            "organization_name": "OneUni University",
            "homepage_uri": "https://oneuni.edu",
            "logo_uri": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAIAAAD8GO2jAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAAEnQAABJ0Ad5mH3gAAAB4SURBVEhLY1Da6ENTNGoBQTRqAUE0Yixwkq3X5tNgAANBkRlosvgQERbM0OaAmAwFNLFAkMNdW2KGkwjIE1S3AIFGLSCIRi0giEYtwIHq5Tk0BCEIaDwIwLh89RiKMRBRFkDNxQBUsoAyNGoBQTRqAUE01C3Y6AMAsDxJowXOs6oAAAAASUVORK5CYII="
          },
          "institution_additional_information": {
            "legal_name": "Board and Trustees of OneUni University"
          },
          "credential_registry_entity": {
            "ctid": "ce-e8a41a52-6ff6-48f0-9872-889c87b093b7",
            "ce_url": "https://credentialengineregistry.org/resources/ce-e8a41a52-6ff6-48f0-9872-889c87b093b7"
          },
          "ror_entity": {
            "rorid": "042nb2s44",
            "ror_url": "https://ror.org/042nb2s44"
          }
        },
        "registry": {
          "type": "oidf",
          "fetchEndpoint": "https://test.registry.dcconsortium.org/fetch?sub=",
          "name": "DCC Member Registry"
        }
      },
      {
        "issuer": {
          "federation_entity": {
            "organization_name": "Issuer Registry Client test",
            "homepage_uri": "https://dcconsortium.org/",
            "location": "here"
          }
        },
        "registry": {
          "type": "dcc-legacy",
          "name": "DCC Community Registry",
          "url": "https://digitalcredentials.github.io/community-registry/registry.json"
        }
      }
    ],
    "uncheckedRegistries": [
      {
        "type": "oidf",
        "fetchEndpoint": "https://registryyyyy.dcconsortium.org/fetch?sub=",
        "name": "DCC Member Registry Not Real"
      }
    ]
  }

Contribute

PRs accepted.

If editing the Readme, please conform to the standard-readme specification.

License

MIT License © 2025 Digital Credentials Consortium.