Dart

Sign PDF in the Cloud using AWS CloudHSM

See more Signing in the Cloud Examples

Demonstrates how to sign a PDF using AWS CloudHSM. The signing of the hash happens on a hardware token in AWS CloudHSM. Everything else involving the updating the PDF to add the signature happens locally within Chilkat.

Note: This example requires Chilkat v9.5.0.96 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.

  // Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

  final pkcs11 = CkPkcs11();

  // Provide the path to the AWS CloudHSM PKCS11 driver.
  // This example runs on Windows, so we'll provide the CloudHSM DLL.
  // If your code runs on Linux, the CloudHSM driver might be at /opt/cloudhsm/lib/libcloudhsm_pkcs11.so
  pkcs11.sharedLibPath = 'C:\\Program Files\\Amazon\\CloudHSM\\lib\\cloudhsm_pkcs11.dll';

  // Your PIN should be a string containing your crypto user's login and password, with a colon char delimiting.
  // See https://docs.aws.amazon.com/cloudhsm/latest/userguide/pkcs11-pin.html
  final pin = 'user:password';
  final userType = 1;

  // Establish a PKCS logged-on session using the driver (.so, .dylib, or .dll) as specified in the SharedLibPath above.
  try {
    pkcs11.quickSession(userType, pin);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final cert = CkCert();
  try {
    cert.loadFromFile('qa_data/certs/myCert.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Tell the certificate to link with the PKCS11 session.
  // The cert's private key should be installed on the CloudHSM.
  // If there are multiple private keys on the CloudHSM, then Chilkat will automatically
  // locate and use the private key corresponding to the certificate.
  try {
    cert.linkPkcs11(pkcs11);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // --------------------------------------------------------------------------
  // At this point, we have the cert to be used for signing.
  // Our PDF signing code is the same as for a cert obtained from any other source..

  final pdf = CkPdf();

  // Load a PDF to be signed.
  try {
    pdf.loadFile('qa_data/pdf/hello.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    pkcs11.closeSession();
    return;
  }

  final json = CkJsonObject();

  json.updateInt('page', 1);
  json.updateString('appearance.y', 'top');
  json.updateString('appearance.x', 'left');
  json.updateString('appearance.fontScale', '10.0');
  json.updateString('signingAlgorithm', 'pss');
  json.updateString('hashAlgorithm', 'sha256');

  var i = 0;
  json.i = i;
  json.updateString('appearance.text[i]', 'Digitaly signed by: Xyz Widgets, Inc.');
  i++;
  json.i = i;
  json.updateString('appearance.text[i]', 'current_dt');
  i++;
  json.i = i;
  json.updateString('appearance.text[i]', 'blah blah blah');

  // The certificate is internally linked to the Pkcs11 object, which is currently in an authenticated session.
  pdf.setSigningCert(cert);

  try {
    pdf.signPdf(json, 'qa_output/out.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    pkcs11.closeSession();
    return;
  }

  // --------------------------------------------------------------------------

  // Revert to an unauthenticated session by calling Logout.
  try {
    pkcs11.logout();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    pkcs11.closeSession();
    return;
  }

  // When finished, close the session.
  // It is important to close the session (memory leaks will occur if the session is not properly closed).
  try {
    pkcs11.closeSession();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Success.');
}