C/C++ Source: signature.cpp

#include <stdio.h>
#import <msxml5.dll>
using namespace MSXML2;
#define PROV_RSA_FULL 1

IXMLDOMDocument3Ptr xmldoc = NULL;
IXMLDigitalSignaturePtr xmldsig = NULL;

VARIANT_BOOL objectsAreInitialized = VARIANT_FALSE;

VARIANT_BOOL loadSignature(_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;
   }

   printf("\nInput signature template:\n\n%s\n", (LPCSTR)xmldoc->xml);

   xmldoc->setProperty("SelectionNamespaces", "xmlns:ds='http://www.w3.org/2000/09/xmldsig#'");

   // 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 signWithKey(long CspType, _bstr_t keyContainer)
{
   if (!objectsAreInitialized) {
      printf("Must initialize object for signing.\n");
      return VARIANT_FALSE;
   }

   // Get the value of the signature property and see if 
      // it has been set.
   if (xmldsig->signature == NULL) {
      printf("Must set signature template before signing.\n");
      return VARIANT_FALSE;
   }

   IXMLDSigKeyPtr dsigKey = xmldsig->createKeyFromCSP(CspType, "", keyContainer,0);
   if (dsigKey == NULL) {
      printf("Failed to create key from CSP\n");
      return VARIANT_FALSE;
   }

   IXMLDSigKeyPtr signedKey = xmldsig->sign(dsigKey, KEYVALUE);
   if (signedKey != NULL) {
      printf("\nThe data referenced in the signature template ");
      printf("was signed successfully.\nResultant signature:\n\n");
      printf("%s\n",(LPCSTR)xmldoc->xml);
   }
   else {
      printf("Signing failed.\n");
      if (dsigKey) dsigKey.Release();
      return VARIANT_FALSE;
   }

   if (dsigKey) dsigKey.Release();
   if (signedKey) signedKey.Release();

   return VARIANT_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;
   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 == loadSignature("signature_template.xml")) {
      // Change this key container name to your own if necessary.
      if (VARIANT_TRUE != signWithKey(PROV_RSA_FULL, "MyRSAFullKeys")) {
         printf("exit with failure.\n");
      }
   }

   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 "signatureProj" 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 signatureProj 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.xml" in the File name text box.
7. Click OK.
8. Copy the XML signature template, and paste it into the text file you just created.
9. Repeat steps 5-8 for the C++ file above (signature.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 signatureProj.exe from the Build menu.
13. Execute the sample application by selecting !Execute signatureProj.exe from the Build menu.
14. Verify that your output is similar to that listed in the Output topic.