Need help to find certificate by Subject name (X500 format, CERT_X500_NAME_STR) using CertFindCertificateInStore()?

Question

A client application has to access certificate from Windows certificate store. The search input is the subject name in X500 string format as below.

"C=CH, S=Aargau, L=Baden, O=Test, OU=FF, CN= Test Root"

An exact match is required (not substring match using CERT_FIND_SUBJECT_STR). For this i do the following

CERT_NAME_BLOB subjectname = {0};

/*convert the input X500 string to encoded subject name*/
bRet = CertStrToNameA(X509_ASN_ENCODING, "C=CH, S=Aargau, L=Baden, O=Test, OU=S1, CN= Test Root", CERT_X500_NAME_STR, NULL, NULL, &size, NULL);
  if(TRUE == bRet)
  {
     subjectname.pbData  = (BYTE*)malloc(size);
     subjectname.cbData = size;

     bRet = CertStrToNameA(X509_ASN_ENCODING , "C=CH, S=Aargau, L=Baden, O=Test, OU=S1, CN=Test Root", CERT_X500_NAME_STR, NULL, subjectname.pbData, &subjectname.cbData, NULL);
     if(TRUE == bRet)
     {
          capiCertificate = CertFindCertificateInStore(hStore, X509_ASN_ENCODING, 0, CERT_FIND_SUBJECT_NAME, &subjectname, NULL);
         if (NULL == capiCertificate)
         {
            errorcode = GetLastError();
            ret = CA_CERT_NOT_FOUND;
         }
     }
  }

The problem is that CertFindCertificateInStore always return NULL pointer. I have been debugging, but could not find out what is going wrong here.

Any suggestions will be very helpful.

what store are you searching your certificate? ie hStore USER or MACHINE? — Raj, Mar 26 '13 at 14:09

score 8 · Accepted Answer · edited Oct 02 '15 at 02:11

In case anyone is looking for an answer to this question, i am posting how i could do it, incase it is useful

static PCCERT_CONTEXT
FindCertificate(
    const HCERTSTORE hStore,
    const char* CertSearchString)
{
    PCCERT_CONTEXT capiCertificate = NULL;
    DWORD dType = CERT_X500_NAME_STR | CERT_NAME_STR_REVERSE_FLAG;
    char certname [MAX_SIZE_CERT_NAME] = {0};

    for(;;)
    {
        capiCertificate = CertEnumCertificatesInStore(hStore, capiCertificate);
        if (NULL == capiCertificate)
        {
            break;
        }

        if (FALSE == 
            CertGetNameStringA(capiCertificate, CERT_NAME_RDN_TYPE,
                0, &dType, certname, MAX_SIZE_CERT_NAME))
        {
            CertFreeCertificateContext(capiCertificate);
            capiCertificate = NULL;
            break;
        }

        if ((0 == strncmp(certname, CertSearchString, MAX_SIZE_CERT_NAME)) &&
            (capiCertificate->dwCertEncodingType == X509_ASN_ENCODING))
        {
            break;
        }
    }
    return capiCertificate;
}

Need help to find certificate by Subject name (X500 format, CERT_X500_NAME_STR) using CertFindCertificateInStore()?

1 Answers1