Someone wrote a cool tool that removes certificates from signed files.

DelCert.cpp

#define _WIN32_WINNT    0x0400   
#include <stdio.h>   
#include <windows.h>   
#include <Wincrypt.h>   
#define MY_ENCODING_TYPE  (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)   
void MyHandleError(char *s);   
   
void main(void)   
{   
//-------------------------------------------------------------------   
// Copyright (c) Microsoft Corporation.  All rights reserved.   
// Declare and initialize variables.   
   
HANDLE          hStoreHandle;   
PCCERT_CONTEXT  pCertContext=NULL;      
PCCERT_CONTEXT  pDupCertContext;    
PCERT_PUBLIC_KEY_INFO pOldPubKey = NULL;   
PCERT_PUBLIC_KEY_INFO pNewPubKey;    
char pszStoreName[256];   
char pszNameString[256];   
char fResponse ='n';     
char x;   
   
//-------------------------------------------------------------------   
// Get the name of the certificate store to open.    
printf("This program maintains the contents of a certificate\n");   
printf("store by allowing you to delete any excess certificates\n");   
printf("from a store. \n\n");   
printf("Please enter the name of the system store to maintain:");   
fgets(pszStoreName, 255, stdin);   
if (pszStoreName[strlen(pszStoreName) - 1] =='\n')   
   pszStoreName[strlen(pszStoreName) - 1] = '\0';   
printf("Certificates will be deleted from "   
       "the %s store.\n",pszStoreName);   
   
//-------------------------------------------------------------------   
// Open a system certificate store.   
   
if ( hStoreHandle = CertOpenSystemStore(   
     NULL,        
     pszStoreName))   
{   
     printf("The %s store has been opened. \n", pszStoreName);   
}   
else   
{   
     MyHandleError("The store was not opened.");   
}   
//-------------------------------------------------------------------   
// Find the certificates in the system store.    
   
while(pCertContext= CertEnumCertificatesInStore(   
    hStoreHandle,   
    pCertContext)) // on the first call to the function,   
                   //  this parameter is NULL   
                   // on all subsequent   
                   //  calls, it is the last pointer returned by    
                   //  the function   
{   
//-------------------------------------------------------------------   
// Get and display the name of the subject of the certificate.   
   
if(CertGetNameString(      
   pCertContext,      
   CERT_NAME_SIMPLE_DISPLAY_TYPE,      
   0,   
   NULL,      
   pszNameString,      
   128))   
{   
   printf("\nCertificate for %s \n",pszNameString);   
}   
else   
{   
   MyHandleError("CertGetName failed.");   
}   
//-------------------------------------------------------------------   
// Check to determine whether the issuer    
// and the subject are the same.   
   
if(CertCompareCertificateName(   
   MY_ENCODING_TYPE,   
   &(pCertContext->pCertInfo->Issuer),   
   &(pCertContext->pCertInfo->Subject)))   
{   
     printf("The certificate subject and issuer are the same.\n");   
}   
else   
{   
     printf("The certificate subject and issuer "   
         "are not the same.\n");   
}   
//--------------------------------------------------------------------   
// Determine whether this certificate's public key matches    
// the public key of the last certificate.   
   
pNewPubKey = &(pCertContext->pCertInfo->SubjectPublicKeyInfo);   
if(pOldPubKey)   
   if(CertComparePublicKeyInfo(   
       MY_ENCODING_TYPE,   
       pOldPubKey,   
       pNewPubKey))   
   {   
       printf("The public keys are the same.\n");   
   }   
   else   
   {   
       printf("This certificate has a different public key.\n");   
   }   
//-------------------------------------------------------------------   
// Reset the old key.   
   
pOldPubKey = pNewPubKey;   
   
//-------------------------------------------------------------------   
// Determine whether this certificate is to be deleted.    
   
printf("Would you like to delete this certificate? (y/n) ");   
fResponse = getchar();   
if(fResponse == 'y')   
{   
   //----------------------------------------------------------------   
   // Create a duplicate pointer to the certificate to be    
   // deleted. In this way, the original pointer is not freed    
   // when the certificate is deleted from the store    
   // and the enumeration of the certificates in the store can   
   // continue. If the original pointer is used, after the    
   // certificate is deleted, the enumeration loop stops.   
   
   if(pDupCertContext = CertDuplicateCertificateContext(   
      pCertContext))   
   {   
       printf("A duplicate pointer was created. Continue. \n");   
   }   
   else   
   {   
        MyHandleError("Duplication of the certificate "   
            "pointer failed.");   
   }   
   
//-------------------------------------------------------------------   
// Compare the pCertInfo members of the two certificates    
// to determine whether they are identical.   
   
if(CertCompareCertificate(   
      X509_ASN_ENCODING,   
      pDupCertContext->pCertInfo,    
      pCertContext->pCertInfo))   
{   
     printf("The two certificates are identical. \n");   
}   
else   
{   
     printf("The two certificates are not identical. \n");   
}   
//-------------------------------------------------------------------   
// Delete the certificate.   
   if(CertDeleteCertificateFromStore(   
     pDupCertContext))      
   {   
       printf("The certificate has been deleted. Continue. \n");   
   }   
   else   
   {   
      printf("The deletion of the certificate failed.\n");   
   }   
} // end if   
   
//-------------------------------------------------------------------   
// Clear the input buffer.   
   
x = getchar();   
   
} // end while   
   
//-------------------------------------------------------------------   
// Clean up.   
   
CertCloseStore(   
   hStoreHandle,   
   0);   
printf("The program ran to completion successfully. \n");   
} // end main   
   
//-------------------------------------------------------------------   
// This example uses the function MyHandleError, a simple error   
// handling function to print an error message and exit    
// the program.    
// For most applications, replace this function with one    
// that does more extensive error reporting.   
   
void MyHandleError(char *s)   
{   
    fprintf(stderr,"An error occurred in running the program. \n");   
    fprintf(stderr,"%s\n",s);   
    fprintf(stderr, "Error number %x.\n", GetLastError());   
    fprintf(stderr, "Program terminating. \n");   
    exit(1);   
} // end MyHandleError