openvc-core 0.3.1

Generic, HSM-friendly Verifiable Credentials core — VC-JWT proofs and DID resolution (key/web) — with an optional read-only EBSI plugin.

openvc

A small, dependency-light Verifiable Credentials core for Python: sign and verify credentials in three proof formats — VC-JWT (JOSE), SD-JWT VC (selective disclosure), and Data Integrity (eddsa-rdfc-2022 and the selective-disclosure ecdsa-sd-2023) — resolve DIDs (did:key, did:web), check status-list revocation, and — via an optional plugin — verify against the EBSI trust registries. Designed so private keys can live behind an HSM/Vault and never enter the process.

It is intentionally not an Open Badges library: openvc is the generic VC machinery that a badge issuer (or an EBSI verifier, or a EUDI wallet backend) builds on. It never imports anything upward.

Why

• VC-JWT first, HSM-friendly. Signing delegates the raw signature to a SigningKey backend, so a PKCS#11 / Vault Transit key is a drop-in — the private key never has to be in-process. ES256 signatures are the correct JOSE raw R‖S form (the classic reason a locally-produced token fails elsewhere).
• Safe by construction. The verifier pins an algorithm allow-list (ES256, EdDSA) before any crypto runs, and reconciles the JWT envelope with the embedded credential. The did:web fetch and the EBSI client both guard against SSRF.
• Version drift, contained. EBSI ships versioned registries whose response shapes change; every version specific lives behind one adapter, so the domain model and trust logic never see wire formats.

Layout

src/openvc/                core — knows nothing about EBSI or badges
    keys.py                Ed25519 (EdDSA) & P-256 (ES256) SigningKey backends
    multibase.py           base58btc multibase + multicodec varint
    proof/vc_jwt.py        VcJwtProofSuite: peek / verify / sign
    proof/sd_jwt.py        SdJwtVcProofSuite: issue / present (key binding) / verify
    proof/data_integrity.py DataIntegrityProofSuite: eddsa-rdfc-2022 (needs pyld)
    proof/ecdsa_sd.py      EcdsaSdProofSuite: ecdsa-sd-2023 selective disclosure
    proof/contexts/        bundled JSON-LD contexts + offline document loader
    did/base.py            DidDocument, resolver protocol, W3C parser, registry
    did/did_key.py         offline did:key (Ed25519, P-256)
    did/did_web.py         did:web -> https -> fetch (fetch is injected)
    fetch.py               SSRF- + DNS-rebinding-safe https JSON fetch for did:web
    status/                status lists — W3C Bitstring + IETF Token Status List
src/openvc_ebsi/           optional EBSI plugin (read-only); depends on openvc only
    http.py                EbsiHttpClient: TTL cache, retries, host allow-list
    versioning.py          DID Registry / TIR version adapters + DidEbsiResolver
    trust.py               recursive TI->TAO->RootTAO trust-chain verification
    verify.py              verify_ebsi_badge: signature + trust + revocation
    models.py              Accreditation, IssuerRecord (version-agnostic domain)

Dependency rule: openvc imports nothing upward. openvc_ebsi depends on openvc, never the reverse.

Install

The PyPI distribution is openvc-core; the Python import package is openvc — so pip install openvc-core, then import openvc.

pip install openvc-core                    # core: VC-JWT, did:key, did:web, status list
pip install "openvc-core[ebsi]"            # + the EBSI registry client (httpx)
pip install "openvc-core[data-integrity]"  # + eddsa-rdfc-2022 Data Integrity (pyld)
pip install -e ".[all]"                    # everything + dev tools (from a checkout)

Quick start

Issue and verify a VC-JWT with an in-process key (swap for an HSM backend in production):

from openvc.keys import P256SigningKey
from openvc.proof.vc_jwt import VcJwtProofSuite

sk = P256SigningKey.generate(kid="did:web:issuer.example#key-1")
suite = VcJwtProofSuite()

credential = {
    "@context": ["https://www.w3.org/2018/credentials/v1"],
    "id": "urn:uuid:...",
    "type": ["VerifiableCredential"],
    "issuer": "did:web:issuer.example",
    "credentialSubject": {"id": "did:key:z6Mk..."},
}
token = suite.sign(credential, signing_key=sk)

verified = suite.verify(token, public_key_jwk=sk.public_jwk())
print(verified.issuer, verified.subject)

Resolve a did:web with the SSRF-guarded fetch, then verify against its key:

from openvc.fetch import default_did_web_resolver

resolver = default_did_web_resolver()          # https-only, blocks private ranges
doc = resolver.resolve("did:web:issuer.example")
vm = doc.key_by_kid("did:web:issuer.example#key-1")
verified = suite.verify(token, public_key_jwk=vm.public_key_jwk)

EBSI (read-only) — resolve a did:ebsi and check issuer trust:

from openvc.proof.vc_jwt import VcJwtProofSuite
from openvc_ebsi.http import for_ebsi
from openvc_ebsi.versioning import DidEbsiResolver
from openvc_ebsi.verify import verify_ebsi_badge

suite = VcJwtProofSuite()
with for_ebsi("pilot") as http:
    resolver = DidEbsiResolver(http.get_json, decode_jwt=suite.peek_claims)
    result = verify_ebsi_badge(token, resolver=resolver, proof_suite=suite,
                               expected_types=["VerifiableAttestation"])
    print(result.trusted, result.issuer)

SD-JWT VC — issue with selective disclosure, then verify a holder presentation (the holder proves possession of the cnf key and reveals only what it chooses):

from openvc.keys import Ed25519SigningKey
from openvc.proof.sd_jwt import SdJwtVcProofSuite

issuer = Ed25519SigningKey.generate(kid="did:web:issuer.example#key-1")
holder = Ed25519SigningKey.generate(kid="did:key:zHolder#0")
suite = SdJwtVcProofSuite()

sd_jwt = suite.issue(
    {"iss": "did:web:issuer.example", "vct": "https://credentials.example/id",
     "given_name": "Ada", "age": 36},
    signing_key=issuer, disclosable=["given_name", "age"],
    holder_jwk=holder.public_jwk(),
)
presentation = suite.create_presentation(
    sd_jwt, holder_key=holder, audience="https://verifier.example", nonce="n-123")

result = suite.verify(
    presentation, public_key_jwk=issuer.public_jwk(),
    audience="https://verifier.example", nonce="n-123", require_key_binding=True)
print(result.claims["given_name"], result.key_bound)

Status

Alpha. The proof suites (VC-JWT, SD-JWT VC, and Data Integrity — eddsa-rdfc-2022, verified byte-for-byte against the official W3C vc-di-eddsa vector, plus the selective-disclosure ecdsa-sd-2023, interop-validated against the official W3C vc-di-ecdsa vectors), the key backends, DID resolution (did:key, did:web, did:ebsi read), the EBSI registry client (verified against recorded pilot fixtures and a live smoke test), the recursive TI→TAO→RootTAO trust chain (with per-hop delegation scoping and revocation of the accreditations themselves), and status-list revocation in both the W3C Bitstring and IETF Token Status List encodings are implemented and tested offline. See the roadmap for what is next.

did:ebsi write/onboarding (JSON-RPC + OID4VP) is out of scope — this is a verifier/issuer library, not a node operator.

Tests

pip install -e ".[all]"
pytest                        # offline: deterministic, no network
OPENVC_EBSI_LIVE=1 pytest     # also the opt-in live EBSI smoke test

Project

• Roadmap
• Changelog
• Contributing (dev setup, checks, and the commit convention)
• Security policy

License

LGPL-3.0-or-later. Copyright © 2026 Luis González Fernández. See COPYING.LESSER and COPYING.