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Signing (XMLDSig)

DGII validates the signature, not the intent. Both SDKs implement XMLDSig enveloped with:

  • Canonicalization: inclusive C14N 1.0 (http://www.w3.org/TR/2001/REC-xml-c14n-20010315)
  • Signature: RSA PKCS#1 v1.5 + SHA-256 (http://www.w3.org/2001/04/xmldsig-more#rsa-sha256)
  • Reference: URI="" with the enveloped-signature transform
  • <Signature> is appended as the last child of the root element.

Why a real canonicalization implementation matters

ElementTree.tostring(), minidom.toxml() and similar serializers are not canonicalization. An off-by-one byte in namespaces or whitespace changes the digest and the document is rejected. The SDKs use real C14N:

  • TypeScript — xml-crypto, which canonicalizes the referenced node-set with inclusive C14N 1.0 before hashing it, then signs with the standard RSA-SHA256 and SHA-256 algorithm URIs.
  • Python — lxml with method="c14n" (inclusive, comments removed).

Sign

import { P12Reader, Signature } from '@deuriib/dgii-ecf';

const credentials = new P12Reader(password).getKeyFromFile('identity.p12');
if (credentials.isErr()) throw credentials.error;

const signed = new Signature(
  credentials.value.key!,
  credentials.value.cert!,
).signXml(xml); // root element auto-detected

from py_dgii_ecf import P12Reader, Signature

credentials = P12Reader(password).get_key_from_file("identity.p12")
if credentials.is_err():
    raise SystemExit(credentials.unwrap_err())

data = credentials.unwrap()
signed = Signature(data.key, data.cert).sign_xml(xml)

Verification gate

A passing local test is necessary, not sufficient. Verify signatures with an independent tool before declaring a signing fix done:

xmlsec1 --verify --insecure signed.xml

Then submit to the DGII certification environment — DGII remains the authority on acceptance.

Fixture tests

The test suites verify the digest and the RSA signature cryptographically (Python) and check the emitted algorithm URIs and structure (TypeScript). Neither is enough on its own: the repository's independent gate signs real fixtures with libxmlsec1 — mise run verify-signing-typescript and uv run --with xmlsec python scripts/verify_signing.py — and runs on every CI push.