Can OpenSSL on Windows use the system certificate store?

Question

Some working C++ code that I'm porting from Linux to Windows is failing on windows because SSL_get_verify_result() is returning X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY.

The code was using SSL_CTX_set_default_verify_paths() on Linux to tell SSL to just look in the standard default locations for the certificate store.

Is it possible to get OpenSSL to use the system certificate store?

Answer 1

I have done it earlier. Hope this helps, if this is exactly what you are looking for.

1. Load your certificate (in PCCERT_CONTEXT structure) from Windows Cert store using Crypto APIs.
2. Get encrypted content of it in binary format as it is. [PCCERT_CONTEXT->pbCertEncoded].
3. Parse this binary buffer into X509 certificate Object using OpenSSL's d2i_X509() method.
4. Get handle to OpenSSL's trust store using SSL_CTX_get_cert_store() method.
5. Load above parsed X509 certificate into this trust store using X509_STORE_add_cert() method.
6. You are done!

Answer 2

For those of you still struggling with this as I have been, here is a sample code to get you started:

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

#include "openssl\x509.h"

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

#define MY_ENCODING_TYPE  (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)

int main(void)
{
    HCERTSTORE hStore;
    PCCERT_CONTEXT pContext = NULL;
    X509 *x509;
    X509_STORE *store = X509_STORE_new();

    hStore = CertOpenSystemStore(NULL, L"ROOT");

    if (!hStore)
        return 1;

    while (pContext = CertEnumCertificatesInStore(hStore, pContext))
    {
        //uncomment the line below if you want to see the certificates as pop ups
        //CryptUIDlgViewContext(CERT_STORE_CERTIFICATE_CONTEXT, pContext,   NULL, NULL, 0, NULL);

        x509 = NULL;
        x509 = d2i_X509(NULL, (const unsigned char **)&pContext->pbCertEncoded, pContext->cbCertEncoded);
        if (x509)
        {
            int i = X509_STORE_add_cert(store, x509);

            if (i == 1)
                std::cout << "certificate added" << std::endl;

            X509_free(x509);
        }
    }

CertFreeCertificateContext(pContext);
CertCloseStore(hStore, 0);
system("pause");
return 0;

}