Dart

Sign String to create a CAdES-T Signature

See more CAdES Examples

This example will sign a string to create a CAdEST-T signature.

Note: This example requires Chilkat v9.5.0.78 or greater.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final crypt = CkCrypt2();

  // This example will use the certificate + private key currently inserted into a smartcard reader.
  final cert = CkCert();

  // If we wish to provide the smartcard PIN (otherwise the user will be prompted by the operating system).
  cert.smartCardPin = '000000';
  try {
    cert.loadFromSmartcard('');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Note: It is also possible to use certs from .pfx/.p12, .pem, or other sources such as 
  // pre-installed Windows certificates.

  crypt.setSigningCert(cert);

  // Use SHA-256 rather than the default of SHA-1
  crypt.hashAlgorithm = 'sha256';

  // Create JSON that tells Chilkat what signing attributes to include:
  final attrs = CkJsonObject();
  attrs.updateBool('contentType', true);
  attrs.updateBool('signingTime', true);
  attrs.updateBool('messageDigest', true);
  attrs.updateBool('signingCertificateV2', true);

  // A CAdES-T signature is one that includes a timestampToken created by an online TSA (time stamping authority).
  // We must include the TSA's URL, as well as a few options to indicate what is desired.
  // Except for the TSA URL, the options shown here are typically what you would need.
  attrs.updateBool('timestampToken.enabled', true);
  attrs.updateString('timestampToken.tsaUrl', 'https://freetsa.org/tsr');
  attrs.updateBool('timestampToken.addNonce', false);
  attrs.updateBool('timestampToken.requestTsaCert', true);
  attrs.updateString('timestampToken.hashAlg', 'sha256');

  crypt.signingAttributes = attrs.emit();

  final strToSign = 'THIS IS MY ID';

  final bd = CkBinData();
  bd.appendString(strToSign, 'utf-8');

  // This creates the CAdES-T signature.  During the signature creation, it
  // communicates with the TSA to get a timestampToken.
  // The contents of bd are signed and replaced with the CAdES-T signature (which embeds the original content).
  try {
    crypt.opaqueSignBd(bd);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the signature in base64 format:
  print(bd.getEncoded('base64_mime'));

  // Or save the signature to a file.
  bd.writeFile('qa_output/cades-t_sample.p7m');

  print('Success.');
}