Igrantio issuer backend
Agent Skills for EUDI Wallet and European Business Wallet integrations: credential issuance (OpenID4VCI), verification (OpenID4VP + DCQL), DC API and consent management on the iGrant.io Organisation Wallet Suite
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What its author says it does
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Build the backend for an OpenID4VCI credential ISSUER against the iGrant.io Organisation Wallet Suite (OWS). A tenant-aware Node/TypeScript (Express) service that hides per-organisation API keys behind a proxy, registers and receives OWS issuance webhooks (HMAC-verified), and pushes live status to the browser over SSE. Use when an application must issue verifiable credentials (SD-JWT VC, W3C VC, mso_mdoc) to an eIDAS 2.0 EUDI Wallet (EUDIW) or European Business Wallet (EUBW) and the API key must never reach the frontend.
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SKILL.md
5.2 KB, as published. Nobody here has run it
iGrant.io issuer backend (OpenID4VCI)
When to use
Build or extend the server that an issuer frontend talks to. It composes three
building blocks for the issuance flow only (least privilege):
igrantio-backend-proxy + igrantio-backend-webhooks + igrantio-backend-sse.
For the verifier equivalent use igrantio-verifier-backend (separate skill). Read
igrantio-ows-overview first for the API and architecture.
Before you build: run the integrator intake in igrantio-ows-overview - environment, API key, tenancy, backend host, webhooks, frontend - one question at a time, a recommended default with each.
What it does
- Proxy
GET|POST|PUT ${PROXY_PREFIX}/{tenant}/...→ OWS, injecting the tenant'sApiKey. Allow-lists only OWS credential endpoints (issue, history). - Register the issuer webhook idempotently (
ISSUER_TOPICS) viascripts/register-webhook.ts. - Receive
POST /webhook, verify theX-iGrant-SignatureHMAC, extract theCredentialExchangeId, store the event. - SSE
GET /webhook/sse/{CredentialExchangeId}streams the event to the browser;DELETE /webhook/{id}lets it consume-and-delete.
Reference implementation
Runnable Express + TypeScript app in ./references:
references/
src/config.ts env config
src/tenants.ts TenantStore - per-tenant API-key resolution (env or pluggable)
src/eventStore.ts in-memory event store (swap for Redis/Postgres)
src/topics.ts ISSUER_TOPICS + topic→exchangeId extraction
src/proxy.ts API-key-injecting reverse proxy (allow-list param)
src/webhooks.ts HMAC verify + receiver
src/sse.ts SSE stream + consume-and-delete
src/server.ts composition (issuer allow-list = credential/* only)
src/registerWebhook.ts idempotent register helper
scripts/register-webhook.ts CLI
.env.example Dockerfile package.json tsconfig.json
Steps
cd references && cp .env.example .env, then setOWS_BASE_URL,WEBHOOK_SECRET_KEY,PUBLIC_BASE_URL,CORS_ORIGINS, and oneOWS_TENANT_<SLUG>_API_KEYper organisation.npm install && npm run dev- backend on:6001.- Register the webhook once per tenant:
npm run register-webhook -- <tenant>(idempotent - safe to re-run; skips if the payloadUrl already exists). - Point the issuer frontend base URL at
${PUBLIC_BASE_URL}${PROXY_PREFIX}/<tenant>and the webhook base at${PUBLIC_BASE_URL}/webhook.
Issuance contract (what the frontend drives through this backend)
POST …/credential/issue→ responsecredentialHistory.CredentialExchangeId(SSE key) +credentialHistory.credentialOffer(QR URI).- Deferred: on webhook
openid.credential.offer_received,PUT …/credential/history/{CredentialExchangeId}with the claims. - Done on webhook
openid.credential.credential_accepted/token_issued. Seeigrantio-ows-overview/references/api-reference.md§1 and §4.
Adapting
- Multi-instance: replace
InMemoryEventStorewith a shared store (Redis/Postgres) implementingEventStore. - Key storage: replace
EnvTenantStorewith a DB/secret-managerTenantStore. - Path scope:
ISSUER_PERMITTED_PREFIXESinserver.tsis the allow-list.
Validation / done criteria
npm run typecheckpasses.- A wrong/absent
X-iGrant-Signatureyields 401; a valid one stores the event. - Hitting a non-credential OWS path through the proxy yields 404 (least privilege).
- The browser SSE fires within ~1s of the webhook arriving, keyed by
CredentialExchangeId.
Documentation & workflows
When anything is unclear, consult the iGrant.io documentation before guessing:
- iGrant.io developer APIs (index): https://docs.igrant.io/docs/developer-apis
- Getting started: https://docs.igrant.io/docs/get-started/
- OpenID4VC API (issuer / verifier / webhook): https://docs.igrant.io/docs/category/openid4vc-api/issuer
- Workflow: issue a credential (OID4VCI): https://docs.igrant.io/docs/openID4vci-issue-credential-intime/
- Configure a webhook: https://docs.igrant.io/docs/openid4vc-api/config-create-webhook