Edit

Share via

Example C Program: Listing the Certificates in a Store

  • Article

The following example code lists all of the certificates in a system certificate store and the name of the subject and all of the certificate context properties of each of those certificates. The example gets the name of the certificate store from the user and thus can be used to list the contents of any system certificate store. In addition, this example shows the use of two new UI functions, one that displays a certificate and the other, UI that allows the user to select a certificate from a list of the certificates in a store.

This example code illustrates the following tasks and CryptoAPI functions:

This example uses the function MyHandleError. Code for this function is included with the sample.

Code for this and other auxiliary functions is also listed under General Purpose Functions.

The following example shows enumerating and displaying the certificates in a store. To compile this example, you must configure your compiler to use a multiple-byte character set.

#include <stdio.h>
#include <windows.h>
#include <wincrypt.h>
#include <cryptuiapi.h>

#include <tchar.h>

#pragma comment (lib, "crypt32.lib")
#pragma comment (lib, "cryptui.lib")

#define MY_ENCODING_TYPE  (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)
void MyHandleError(char *s);

void main(void)
{

//-------------------------------------------------------------------
// Copyright (C) Microsoft.  All rights reserved.
// This program lists all of the certificates in a system certificate
// store and all of the property identifier numbers of those 
// certificates. It also demonstrates the use of two
// UI functions. One, CryptUIDlgSelectCertificateFromStore, 
// displays the certificates in a store
// and allows the user to select one of them, 
// The other, CryptUIDlgViewContext,
// displays the contents of a single certificate.

//-------------------------------------------------------------------
// Declare and initialize variables.

HCERTSTORE       hCertStore;        
PCCERT_CONTEXT   pCertContext=NULL;      
char pszNameString[256];
char pszStoreName[256];
void*            pvData;
DWORD            cbData;
DWORD            dwPropId = 0; 
            // Zero must be used on the first
            // call to the function. After that,
            // the last returned property identifier is passed.

//-------------------------------------------------------------------
//  Begin processing and Get the name of the system certificate store 
//  to be enumerated. Output here is to stderr so that the program  
//  can be run from the command line and stdout can be redirected  
//  to a file.

fprintf(stderr,"Please enter the store name:");
gets_s(pszStoreName, sizeof(pszStoreName));
fprintf(stderr,"The store name is %s.\n",pszStoreName);

//-------------------------------------------------------------------
// Open a system certificate store.

if ( hCertStore = CertOpenSystemStore(
     NULL,
     pszStoreName))
{
     fprintf(stderr,"The %s store has been opened. \n", 
          pszStoreName);
}
else
{
// If the store was not opened, exit to an error routine.
     MyHandleError("The store was not opened.");
}

//-------------------------------------------------------------------
// Use CertEnumCertificatesInStore to get the certificates 
// from the open store. pCertContext must be reset to
// NULL to retrieve the first certificate in the store.
 
// pCertContext = NULL;

while(pCertContext= CertEnumCertificatesInStore(
     hCertStore,
     pCertContext))
{
//-------------------------------------------------------------------
// A certificate was retrieved. Continue.
//-------------------------------------------------------------------
//  Display the certificate.

if ( CryptUIDlgViewContext(
  CERT_STORE_CERTIFICATE_CONTEXT,
  pCertContext,
  NULL,
  NULL,
  0,
  NULL))
{
//     printf("OK\n");
}
else
{
    MyHandleError("UI failed.");
}

if(CertGetNameString(
   pCertContext,
   CERT_NAME_SIMPLE_DISPLAY_TYPE,
   0,
   NULL,
   pszNameString,
   128))
{
   printf("\nCertificate for %s \n",pszNameString);
}
else
   fprintf(stderr,"CertGetName failed. \n");

//-------------------------------------------------------------------
// Loop to find all of the property identifiers for the specified  
// certificate. The loop continues until 
// CertEnumCertificateContextProperties returns zero.

while(dwPropId = CertEnumCertificateContextProperties(
       pCertContext, // The context whose properties are to be listed.
       dwPropId))    // Number of the last property found.  
                     // This must be zero to find the first 
                     // property identifier.
{
//-------------------------------------------------------------------
// When the loop is executed, a property identifier has been found.
// Print the property number.

   printf("Property # %d found->", dwPropId);

//-------------------------------------------------------------------
// Indicate the kind of property found.

   switch(dwPropId)
   {
     case CERT_FRIENDLY_NAME_PROP_ID:
     {
       printf("Display name: ");
       break;
     }
     case CERT_SIGNATURE_HASH_PROP_ID:
     {
       printf("Signature hash identifier ");
       break;
     }
     case CERT_KEY_PROV_HANDLE_PROP_ID:
     {
       printf("KEY PROVE HANDLE");
       break;
     }
     case CERT_KEY_PROV_INFO_PROP_ID:
     {
       printf("KEY PROV INFO PROP ID ");
       break;
     }
     case CERT_SHA1_HASH_PROP_ID:
     {
        printf("SHA1 HASH identifier");
        break;
     }
     case CERT_MD5_HASH_PROP_ID:
     {
        printf("md5 hash identifier ");
        break;
     }
     case CERT_KEY_CONTEXT_PROP_ID:
     {
        printf("KEY CONTEXT PROP identifier");
        break;
     }
     case CERT_KEY_SPEC_PROP_ID:
     {
        printf("KEY SPEC PROP identifier");
        break;
      }
      case CERT_ENHKEY_USAGE_PROP_ID:
      {
        printf("ENHKEY USAGE PROP identifier");
        break;
      }
      case CERT_NEXT_UPDATE_LOCATION_PROP_ID:
      {
        printf("NEXT UPDATE LOCATION PROP identifier");
        break;
      }
      case CERT_PVK_FILE_PROP_ID:
      {
         printf("PVK FILE PROP identifier ");
         break;
      }
      case CERT_DESCRIPTION_PROP_ID:
      {
        printf("DESCRIPTION PROP identifier ");
        break;
      }
      case CERT_ACCESS_STATE_PROP_ID:
      {
        printf("ACCESS STATE PROP identifier ");
        break;
      }
      case CERT_SMART_CARD_DATA_PROP_ID:
      {
         printf("SMART_CARD DATA PROP identifier ");
         break;
      }
      case CERT_EFS_PROP_ID:
      {
        printf("EFS PROP identifier ");
        break;
      }
      case CERT_FORTEZZA_DATA_PROP_ID:
      {
        printf("FORTEZZA DATA PROP identifier ");
        break;
      }
      case CERT_ARCHIVED_PROP_ID:
      {
        printf("ARCHIVED PROP identifier ");
        break;
      }
      case CERT_KEY_IDENTIFIER_PROP_ID:
      {
        printf("KEY IDENTIFIER PROP identifier ");
        break;
      }
      case CERT_AUTO_ENROLL_PROP_ID:
      {
        printf("AUTO ENROLL identifier. ");
        break;
      }
   } // End switch.

//-------------------------------------------------------------------
// Retrieve information on the property by first getting the 
// property size. 
// For more information, see CertGetCertificateContextProperty.

   if(CertGetCertificateContextProperty(
         pCertContext, 
         dwPropId , 
         NULL, 
         &cbData))
    {
    //  Continue.
    }
    else
    {  
    // If the first call to the function failed,
    // exit to an error routine.
        MyHandleError("Call #1 to GetCertContextProperty failed.");
    }
//-------------------------------------------------------------------
// The call succeeded. Use the size to allocate memory 
// for the property.
   
   if(pvData = (void*)malloc(cbData))
   {
   // Memory is allocated. Continue.
   }
   else
   {
   // If memory allocation failed, exit to an error routine.
      MyHandleError("Memory allocation failed.");
   }
   //----------------------------------------------------------------
   // Allocation succeeded. Retrieve the property data.
   
   if(CertGetCertificateContextProperty(
      pCertContext,
      dwPropId,
      pvData, 
      &cbData))
    {
    // The data has been retrieved. Continue.
    }
    else
    {
    // If an error occurred in the second call, 
    // exit to an error routine.
      MyHandleError("Call #2 failed.");
    }
    //---------------------------------------------------------------
    // Show the results.

   printf("The Property Content is %d \n", pvData);
     
   //----------------------------------------------------------------
   // Free the certificate context property memory.
    
   free(pvData);
  }  // End inner while.
} // End outer while.

//-------------------------------------------------------------------
// Select a new certificate by using the user interface.

if(!(pCertContext = CryptUIDlgSelectCertificateFromStore(
  hCertStore,
  NULL,
  NULL,
  NULL,
  CRYPTUI_SELECT_LOCATION_COLUMN,
  0,
  NULL)))
{
    MyHandleError("Select UI failed." );
}


//-------------------------------------------------------------------
// Clean up.

CertFreeCertificateContext(pCertContext);
CertCloseStore(hCertStore,0);
printf("The function completed successfully. \n");
} // End of main.


void MyHandleError(LPTSTR psz)
{
    _ftprintf(stderr, TEXT("An error occurred in the program. \n"));
    _ftprintf(stderr, TEXT("%s\n"), psz);
    _ftprintf(stderr, TEXT("Error number %x.\n"), GetLastError());
    _ftprintf(stderr, TEXT("Program terminating. \n"));
    exit(1);
} // End of MyHandleError.