C/C++ Source: sign.cpp

This C++ code example makes use of smart pointer class wrappers around the interface.

#include <stdio.h>
#import <msxml5.dll>
using namespace MSXML2;

#define DSIGNS "xmlns:ds='http://www.w3.org/2000/09/xmldsig#'"
// Change this key container name to your own if necessary.
#define RSA_KEY "MyRSAFullKeys"
#define INFILE "signature_template.sign.rsa.xml"

IXMLDOMDocument3Ptr xmldoc = NULL;
IXMLDigitalSignaturePtr xmldsig = NULL;
VARIANT_BOOL objectsAreInitialized = VARIANT_FALSE;

VARIANT_BOOL LoadXML(_bstr_t sigFile)
{
   if (!objectsAreInitialized) {
      printf("Must initialize objects before loading signature.\n");
      return VARIANT_FALSE;
   }

   if (xmldoc->load(sigFile) == VARIANT_FALSE) {
      printf("Can't load %s\n", (LPCSTR)sigFile);
      return VARIANT_FALSE;
   }

   xmldoc->setProperty("SelectionNamespaces", DSIGNS);

   // set the signature property to a <ds:Signature> DOM node.
   xmldsig->signature = xmldoc->selectSingleNode(".//ds:Signature");

   if (xmldsig->signature == NULL) {
      printf("Failed to set the signature property.\n");
      return VARIANT_FALSE;
   }

   return VARIANT_TRUE;

}
VARIANT_BOOL SignXML(XMLDSIG_WRITEKEYINFO fwWriteKeyInfo)
{
   if (xmldsig->signature == NULL) {
      printf("Invalid signature template\n");
      return false;
   }

   IXMLDSigKeyPtr pKey = xmldsig->createKeyFromCSP(
            PROV_RSA_FULL, "", RSA_KEY, 0);
   if (pKey==NULL) {
      printf("Invalid key\n");
      return false;
   }

   IXMLDSigKeyPtr pKeyOut = xmldsig->sign(pKey, fwWriteKeyInfo);
   if (NULL == pKeyOut) {
      printf("sign failed.\n");
      return false;
   }

   printf("The specified data was signed successfully.\n");
   printf("Resultant signature:\n");
   printf((LPCSTR)xmldoc->xml);
   printf("\n");

   return true;
}


VARIANT_BOOL initObjects()
{
   if (FAILED(xmldsig.CreateInstance(__uuidof(MXDigitalSignature50)) )) {
      printf("Installation of msxml5 is required to run this app.\n");
      return VARIANT_FALSE;
   }

   if (FAILED(xmldoc.CreateInstance(__uuidof(DOMDocument50)) )) {
      printf("Installation of msxml5 is required to run this app.\n");
      return VARIANT_FALSE;
   }
   xmldoc->async = VARIANT_FALSE;
   xmldoc->validateOnParse = VARIANT_FALSE;
   xmldoc->preserveWhiteSpace = VARIANT_TRUE;
   xmldoc->resolveExternals = VARIANT_FALSE;

   objectsAreInitialized = VARIANT_TRUE;

   return VARIANT_TRUE;
}

void cleanObjects()
{
   if (xmldoc) xmldoc.Release();
   if (xmldsig) xmldsig.Release();
}

void main() 
{

   if ( CoInitialize(NULL) == E_FAIL) {
      printf("can't initialize COM Lib\n");
      exit(-1);
   }

   if (!initObjects()) {
      cleanObjects();
      exit(-1);
   }

   if (VARIANT_TRUE == LoadXML(INFILE)) {
      printf("Sign with fwWriteKeyInfo = NOKEYINFO:\n");
      SignXML(NOKEYINFO);

      printf("Sign with fwWriteKeyInfo = KEYVALUE:\n");
      SignXML(KEYVALUE);

      printf("Sign with fwWriteKeyInfo = CERTIFICATES:\n");
      SignXML(CERTIFICATES);

      printf("Sign with fwWriteKeyInfo = CERTIFICATES|PURGE:\n");
      SignXML(XMLDSIG_WRITEKEYINFO(CERTIFICATES|PURGE));

      printf("Sign with fwWriteKeyInfo = PURGE:\n");
      SignXML(PURGE);
   }

   cleanObjects();
   CoUninitialize();
}

Try It!

1. Ensure that you have completed all the procedures in Getting Started with XML Digital Signatures.
2. Start Visual C++.
3. From the File menu, select New. On the Projects tab of the New dialog box that appears, select Win32 Console Application in the left pane. Then type "signProj" in the Project name field. For the project Location field, either accept the default setting or choose another location. Click OK.
4. The Win32 Console Application property page will appear. For the type of Console Application, select An empty project and click Finish. When the New Project Information box displays, click OK.
5. Select FileView on the project browser, and highlight signProj files. From the File menu, select New.
6. On the Files tab of the New dialog box, highlight C++ Source File. Then type "signature_template.sign.rsa.xml" in the File name text box.
7. Click OK.
8. Copy the XML signature template resource file, and paste it into the text file you just created.

   Note   You can also copy the file into the project's main directory using Windows Explorer (or a command prompt).

9. Repeat steps 5-8 for the C++ file above (sign.cpp).
10. From the Project menu, click Settings..., then click the Link tab.
11. In Object/library modules, type "crypt32.lib". Insert this text either before or after the existing string that lists all objects and modules for the current project. Then click OK.
12. Build the sample by selecting Build signProj.exe from the Build menu.
13. Execute the sample application by selecting !Execute signProj.exe from the Build menu.
14. Verify that your output is the similar to that listed in the Output topic.