Dart

Create XML Digital Signature using Certificate on Smart Card

See more ScMinidriver Examples

Demonstrates how to load a certificate located on a smart card or USB token and then use it for creating an XML digital signature such that the cryptographic signing happens on the smart card. 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 scmd = CkScMinidriver();

  // Reader names (smart card readers or USB tokens) can be discovered
  // via List Readers or Find Smart Cards
  final readerName = 'SCM Microsystems Inc. SCR33x USB Smart Card Reader 0';
  try {
    scmd.acquireContext(readerName);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // If successful, the name of the currently inserted smart card is available:
  print('Card name: ${scmd.cardName}');

  // If desired, perform regular PIN authentication with the smartcard.
  // For more details about smart card PIN authentication, see the Smart Card PIN Authentication Example
  final retval = scmd.pinAuthenticate('user', '000000');
  if (retval != 0) {
    print('PIN Authentication failed.');
  }

  // You can find a cerficate using any of the following certificate parts:
  // "subjectDN" -- The full distinguished name of the cert.
  // "subjectDN_withTags" -- Same as above, but in a format that includes the subject part tags, such as the "CN=" in "CN=something"
  // "subjectCN" -- The common name part (CN) of the certificate's subject.
  // "serial" -- The certificate serial number.
  // "serial:issuerCN" -- The certificate serial number + the issuer's common name, delimited with a colon char.
  // These are the same certificate parts that can be retrieved by listing certificates on the smart card (or USB token).
  // See List Certificates on Smart Card Example
  final certPart = 'subjectCN';
  final partValue = 'PIVKey E42D60A759D39147A26E0AF2FB1183C5';

  // If the certificate is found, it is loaded into the cert object.
  final cert = CkCert();
  try {
    scmd.findCert(certPart, partValue, cert);
  } on ChilkatException {
    print('Failed to find the certificate.');
    scmd.deleteContext();
    return;
  }

  print('Successfully loaded the cert object from the smart card / USB token.');

  // Note: When successful, the cert object is internally linked to the ScMinidriver object's authenticated session.
  // The cert object can now be used to sign or do other cryptographic operations that occur on the smart card / USB token.
  // If your application calls PinDeauthenticate or DeleteContext, the cert will no longer be able to sign on the smart card
  // because the smart card ScMinidriver session will no longer be authenticated or deleted.

  // ------------------------------------------------------------------------------------------------------------
  // We have the certificate.  Now let's do the XML digital signature..

  // Create the following XML to be signed:

  // <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
  // <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  //     <SOAP-ENV:Header>
  //         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1"></wsse:Security>
  //     </SOAP-ENV:Header>
  //     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
  //         <z:FooBar xmlns:z="http://example.com" />
  //     </SOAP-ENV:Body>
  // </SOAP-ENV:Envelope>

  final xml = CkXml();
  xml.tag = 'SOAP-ENV:Envelope';
  xml.addAttribute('xmlns:SOAP-ENV', 'http://schemas.xmlsoap.org/soap/envelope/');
  xml.updateAttrAt('SOAP-ENV:Header|wsse:Security', true, 'xmlns:wsse', 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd');
  xml.updateAttrAt('SOAP-ENV:Header|wsse:Security', true, 'SOAP-ENV:mustUnderstand', '1');
  xml.updateAttrAt('SOAP-ENV:Body', true, 'xmlns:SOAP-SEC', 'http://schemas.xmlsoap.org/soap/security/2000-12');
  xml.updateAttrAt('SOAP-ENV:Body', true, 'SOAP-SEC:id', 'Body');
  xml.updateAttrAt('SOAP-ENV:Body|z:FooBar', true, 'xmlns:z', 'http://example.com');

  // Prepare for signing...
  final gen = CkXmlDSigGen();

  // Indicate where the Signature will be inserted.
  gen.sigLocation = 'SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security';

  // Add a reference to the fragment of the XML to be signed.

  // Note: "Body" refers to the XML element having an "id" equal to "Body", where "id" is case insensitive
  // and where any namespace might qualify the attribute.  In this case, the SOAP-ENV:Body fragment is signed
  // NOT because the tag = "Body", but because it has SOAP-SEC:id="Body"
  gen.addSameDocRef('Body', 'sha1', 'EXCL_C14N', '', '');

  // (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
  gen.signedInfoPrefixList = 'wsse SOAP-ENV';

  // Provide the private key for signing via the certificate, and indicate that
  // we want the base64 of the certificate embedded in the KeyInfo.
  gen.keyInfoType = 'X509Data';
  gen.x509Type = 'Certificate';

  // Note: Our certificate was loaded from the smartcard and is internally linked to the authenticated ScMinidriver session.
  // The signing will occur on the smart card using the chosen certificate.
  final bUsePrivateKey = true;
  try {
    gen.setX509Cert(cert, bUsePrivateKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Everything's specified.  Now create and insert the Signature
  final sbXml = CkStringBuilder();
  xml.getXmlSb(sbXml);
  try {
    gen.createXmlDSigSb(sbXml);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Examine the XML with the digital signature inserted
  print(sbXml.getAsString());

  // ------------------------------------------------------------------------------------------------------------
  // Cleanup our ScMinidriver session...

  // When finished with operations that required authentication, you may if you wish, deauthenticate the session.
  try {
    scmd.pinDeauthenticate('user');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
  }

  // Delete the context when finished with the card.
  try {
    scmd.deleteContext();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
  }
}