BOOL WINAPI CertSerializeCertificateStoreElement(
  __in     PCCERT_CONTEXT pCertContext,
  __in     DWORD dwFlags,
  __out    BYTE *pbElement,
  __inout  DWORD *pcbElement
);

#include <stdio.h>
#include <windows.h>
#include <Wincrypt.h>
#pragma comment(lib, "crypt32.lib")

void main()
{
    //---------------------------------------------------------------
    // Copyright (c) Microsoft Corporation.  All rights reserved.
    // Declare and initialize variables.
    HCERTSTORE         hCertStore = NULL;
    PCCERT_CONTEXT     pCertContext = NULL;
    BYTE*              pbElement;
    DWORD              cbElement;

    //---------------------------------------------------------------
    // Open a system certificate store.
    if(hCertStore = CertOpenSystemStore(
        0,
        "CA"))
    {
      printf("The CA system store is open. Continue.\n");
    }
    else
    {
      printf("The system store did not open.\n");
      exit(1);
    }

    //----------------------------------------------------------------
    // Retrieve a certificate from the store.
    // CertFindCertificateInStore could be used here to find
    // a certificate with a specific property.
    if(pCertContext=CertEnumCertificatesInStore(
        hCertStore,
        pCertContext))
    {
         printf("A certificate is available. Continue.\n");
    }
    else
    {
         printf("No certificate available. The store may "
			 "be empty.\n");
         CertCloseStore(hCertStore,0);
         exit(1);
    }

    //---------------------------------------------------------------
    // Find out how much memory to allocate for the serialized 
	// element.
    if(CertSerializeCertificateStoreElement(
        pCertContext,      // The existing certificate.
        0,                 // Accept default for dwFlags, 
        NULL,              // NULL for the first function call.
        &cbElement))       // Address where the length of the 
                           // serialized element will be placed.
    {
         printf("The length of the serialized string is %d.\n",
			 cbElement);
    }
    else
    {
         printf("Finding the length of the serialized element "
			 "failed.\n");
         CertCloseStore(hCertStore,0);
         exit(1);
    }

    //---------------------------------------------------------------
    // Allocate memory for the serialized element.
    if(pbElement = (BYTE*)malloc(cbElement))
    {
         printf("Memory has been allocated. Continue.\n");
    }
    else
    {
         printf("The allocation of memory failed.\n");
         CertCloseStore(hCertStore,0);
         exit(1);
    }

    //---------------------------------------------------------------
    // Create the serialized element from the certificate context.
    if(CertSerializeCertificateStoreElement(
        pCertContext,        // The certificate context source for  
                             // the serialized element.
        0,                   // dwFlags. Accept the default.
        pbElement,           // A pointer to where the new element 
                             // will be stored.
        &cbElement))         // The length of the serialized element,
    {
         printf("The encoded element has been serialized. \n");
    }
    else
    {
         printf("The element could not be serialized.\n");
         CertCloseStore(hCertStore,0);
         exit(1);
    }

    //---------------------------------------------------------------
    // pbElement could be written to a file or be sent by e-mail
    // to another user (not shown). 
    // ...

    //---------------------------------------------------------------
    //  When all processing is done, clean up.
    free(pbElement);
    CertCloseStore(hCertStore,0);
}