Dart

Sign String to create a CAdES-T Signature, using HTTP Proxy to Access Timestamp Server

This example will sign a string to create a CAdEST-T signature. It will use an HTTP proxy to access the timestamp server. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final crypt = CkCrypt2();

  final cert = CkCert();
  cert.smartCardPin = '123456';
  try {
    cert.loadFromSmartcard('');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  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 = 'Hello World!';

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

  // -------------------------------------------------------------------------
  // The purpose of this example is to show how an HTTP object with custom
  // settings can be used to access the Internet when signing.
  // Access to the Internet is needed to communicate with the timestamp server.
  final http = CkHttp();
  // This can be a domain name, hostname, or IP address.
  http.proxyDomain = '172.16.16.56';
  http.proxyPort = 808;
  http.proxyLogin = 'myProxyLogin';
  http.proxyPassword = 'myProxyPassword';
  crypt.setTsaHttpObj(http);
  // -------------------------------------------------------------------------

  // 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'));

  print('Success.');
}