Dart

Sign PDF using PAdES-Baseline-B

See more PDF Signatures Examples

PAdES-Baseline-B is the most basic, entry-level profile of the PDF Advanced Electronic Signatures (PAdES) standard.

It means:

• A PDF contains a CMS/PKCS#7 detached signature over the document’s byte range.
• /SubFilter must be ETSI.CAdES.detached.
• The signer’s X.509 certificate is included inside the signature.
• The signature uses recognized secure algorithms (e.g., SHA-256 with RSA/ECDSA).
• It proves document integrity (no changes since signing) and signer authenticity (certificate identifies who signed).
• It does not include time-stamps, revocation data (CRL/OCSP), or long-term validation information — those appear only in higher levels (PAdES-Baseline-T, -LT, -LTA).

In short: Baseline-B = a standard PDF digital signature that ensures integrity and origin, but without time or revocation guarantees.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final pdf = CkPdf();

  // Load a PDF to be signed.
  try {
    pdf.loadFile('c:/someDir/my.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Options for signing are specified in JSON.
  final json = CkJsonObject();

  json.updateString('subFilter', '/ETSI.CAdES.detached');
  json.updateBool('signingCertificateV2', true);
  json.updateBool('signingTime', true);
  json.updateString('signingAlgorithm', 'pkcs');
  json.updateString('hashAlgorithm', 'sha256');

  // -----------------------------------------------------------
  // The following JSON settings define the signature appearance.
  json.updateInt('page', 1);
  json.updateString('appearance.y', 'top');
  json.updateString('appearance.x', 'left');
  json.updateString('appearance.fontScale', '10.0');
  json.updateString('appearance.text[0]', 'Digitally signed by: cert_cn');
  json.updateString('appearance.text[1]', 'current_dt');
  json.updateString('appearance.text[2]', 'Hello 123 ABC');

  // --------------------------------------------------------------
  // Load the signing certificate. (Use your own certificate.)
  // Note: There are other methods for using a certificate on an HSM (smartcard or token)
  // or from other sources, such as a cloud HSM, a Windows installed certificate,
  // or other file formats.
  final cert = CkCert();
  try {
    cert.loadPfxFile('c:/myPfxFiles/myPdfSigningCert.pfx', 'pfxPassword');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Once we have the certificate object, tell the PDF object to use it for signing
  try {
    pdf.setSigningCert(cert);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Sign the PDF, creating the output file.
  final outFilePath = 'c:/someDir/mySigned.pdf';
  try {
    pdf.signPdf(json, outFilePath);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Success.');
}