需要帮助来按模板检索Windows证书吗？

Question

I need to retrieve a Windows Certificate by Template Name (The Template is in the Extension Fields) using Windows API, C++.

My steps:

1. Open store: CertOpenStore(..) (Done; I can enumerate the certificates using CertEnumCertificatesInStore(..), but I see only their "Version 1 fields" and not the "Extensions". The Template is in the Extensions, so I cannot find it.)

2. I tried to find it using the CertFindCertificateInStore(), but did not succeed. Can anyone help me with the correct find type and parameters or use another function?

3. CertFreeCertificateContext(..), CertCloseStore(..) (Done).

Answer 1

I would like to post my code, hope it helps someone.

void GetCertificateByTemplate(char *certificateTemplate)
{
    HCERTSTORE          hCertStore;
    PCCERT_CONTEXT      pCertContext = NULL;
    BYTE               *pbDecoded;
    DWORD               cbDecoded;
    _CERT_TEMPLATE_EXT *pbDecodedTemplate = NULL;

    // 1). Open Local Machine certificate store
    if (hCertStore = CertOpenStore(
        CERT_STORE_PROV_SYSTEM,
        0,
        NULL,
        CERT_SYSTEM_STORE_LOCAL_MACHINE,
        L"My"))
    {
        fprintf(stderr, "The store has been opened. \n");
    }

    // 2). Enumerate certificates
    while (pCertContext = CertEnumCertificatesInStore(
        hCertStore,
        pCertContext))
    {
        // 3). Check certificate extended data
        for (int i = 0; i < pCertContext->pCertInfo->cExtension; i++)
        {
            // 4). Decode certificate extended data
            if (CryptDecodeObject(
                X509_ASN_ENCODING,
                pCertContext->pCertInfo->rgExtension[i].pszObjId,
                pCertContext->pCertInfo->rgExtension[i].Value.pbData,
                pCertContext->pCertInfo->rgExtension[i].Value.cbData,
                0,
                NULL,
                &cbDecoded))
            {
                ; // error !!!
            }
            if (!(pbDecoded = (BYTE*)malloc(cbDecoded)))
            {
                ; // error !!!
            }
            if (CryptDecodeObject(
                X509_ASN_ENCODING,
                pCertContext->pCertInfo->rgExtension[i].pszObjId,
                pCertContext->pCertInfo->rgExtension[i].Value.pbData,
                pCertContext->pCertInfo->rgExtension[i].Value.cbData,
                0,
                pbDecoded,
                &cbDecoded))
            {
                pbDecodedTemplate = (_CERT_TEMPLATE_EXT*)pbDecoded;

                char* objectId = pbDecodedTemplate->pszObjId;

                // todo: check pDecodeTemplate->pszObjId

                // 5). Compare the template string with the search one
                if (strcmp(pbDecodedTemplate->pszObjId, certificateTemplate) == 0)
                {
                    // todo: return certificate
                    printf("\nCertificate template found: %s \n", pbDecodedTemplate->pszObjId);   
                    break;
                }
            }
        }
    }

    // 6). Free certificate, close store
    if (pCertContext)
    {
        CertFreeCertificateContext(pCertContext);
    }
    CertCloseStore(hCertStore, 0);
}