Question

我需要为Windows编写一个C程序，它从网络接收证书（采用PEM格式），并使用证书链文件（已在应用程序的文件夹中显示）验证其签名。

使用openssl库编写这样的应用程序非常容易并且前进很好但是使用Windows Crypto API似乎有些复杂。

这是我到目前为止所尝试的内容：

首先我想我可以使用证书链文件创建一个HCERTSTORE：

HCERTSTORE hFileStoreHandle = CertOpenStore( 
CERT_STORE_PROV_FILENAME,
PKCS_7_ASN_ENCODING | X509_ASN_ENCODING, NULL,
(CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG),
L"certificate-chain.pem.cert");

然后我想我可以遍历商店并获得证书的PCCERT_CONTEXT结构：

PCCERT_CONTEXT CAfileContext = NULL;
while(CAfileContext = CertEnumCertificatesInStore(
 hCertStore,
 CAfileContext)) {

    //start verification here
}

我不知道我是否走在正确的轨道上，但我在这里遇到两个主要问题。

首先，我不知道如何从缓冲区获取收到的证书，并将其转换为正确的结构，以便使用证书链文件验证其签名。

其次是我不知道如何使用CA链文件验证证书签名。

我会感谢所有的建议和帮助。

Answer 1

这是为您提供的示例代码，希望它可以为您提供帮助。

HRESULT hr = E_FAIL;
DWORD dwError = 0;
PCCERT_CONTEXT  pCert = NULL;

HCERTSTORE hCertStore = CertOpenStore(
    CERT_STORE_PROV_FILENAME,                   
    PKCS_7_ASN_ENCODING | X509_ASN_ENCODING,
    NULL,                                   
    (CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG),             
    L"certificate-chain.pem.cert");

do
{
    if ((pCert = CertEnumCertificatesInStore(hCertStore, pCert)) == NULL)
        break;

    PCCERT_CONTEXT pcIssuer = NULL;
    PCCERT_CONTEXT pcSubject = CertDuplicateCertificateContext(pCert);
    for (; NULL != pcSubject;)
    {
        DWORD dwFlags = 0;
        BOOL bret = TRUE;
        hr = S_OK;

        pcIssuer = CertGetIssuerCertificateFromStore(
            hCertStore, pcSubject, NULL, &dwFlags);

        if (pcIssuer == NULL)
        {
            dwError = GetLastError();
            if (CRYPT_E_SELF_SIGNED != dwError)
            {
                hr = E_FAIL;
                break;
            }
            else
            {
                if ((bret = CertCompareCertificateName(
                    X509_ASN_ENCODING, 
                    &pcSubject->pCertInfo->Subject, 
                    &pcSubject->pCertInfo->Issuer)) == FALSE)
                {
                    hr = E_FAIL;
                    break;
                }
            }
        }

        HCRYPTPROV hprov = NULL;
        bret = CryptAcquireContext(
                    &hprov, nullptr, nullptr, PROV_RSA_FULL, 
                    CRYPT_SILENT | CRYPT_VERIFYCONTEXT | CRYPT_NEWKEYSET);

        if (FALSE == bret)
        {
            dwError = GetLastError();
            if (NTE_EXISTS == dwError)
                bret = CryptAcquireContext(
                        &hprov, nullptr, nullptr, PROV_RSA_FULL,
                        CRYPT_SILENT | CRYPT_VERIFYCONTEXT);
            if (FALSE == bret)
            {
                hr = E_FAIL;
                break;
            }
        }

        if ((bret = CryptVerifyCertificateSignatureEx(
            hprov, X509_ASN_ENCODING,
            CRYPT_VERIFY_CERT_SIGN_SUBJECT_CERT,
            (void*)pcSubject,
            CRYPT_VERIFY_CERT_SIGN_SUBJECT_CERT, 
            (void*)(pcIssuer == nullptr ? pcSubject : pcIssuer),
            0, nullptr)) == FALSE)
        {
            hr = E_FAIL;
            break;
        }

        if (nullptr == pcIssuer)
        {
            CERT_PUBLIC_KEY_INFO msCert;
            msCert.Algorithm = 
                pcSubject->pCertInfo->SubjectPublicKeyInfo.Algorithm;
            msCert.PublicKey.cbData = 
                sizeof(PETRUSTED_ROOTCERT_PUBKEY);
            msCert.PublicKey.pbData = 
                const_cast<LPBYTE>(PETRUSTED_ROOTCERT_PUBKEY);
            msCert.PublicKey.cUnusedBits = 
                pcSubject->pCertInfo->SubjectPublicKeyInfo.PublicKey.cUnusedBits;

            if (FALSE == CertComparePublicKeyInfo(
                X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, 
                &pcSubject->pCertInfo->SubjectPublicKeyInfo, &msCert))
            {
                hr = E_FAIL;
                break;
            }
        }

        bret = CryptReleaseContext(hprov, 0);
        hprov = NULL;

        CertFreeCertificateContext(pcSubject);
        pcSubject = pcIssuer;
        pcIssuer = NULL;
    }

    if (pcIssuer != NULL)
        CertFreeCertificateContext(pcIssuer);

    if (pcSubject != NULL)
        CertFreeCertificateContext(pcSubject);

    if (FAILED(hr))
    {
        CertFreeCertificateContext(pCert);
        break;
    }

} while (pCert != NULL);

CertCloseStore(hCertStore, 0);

if (FAILED(hr))
    wprintf(L"Failed to verify X509 certification.\n");
else
    wprintf(L"Successfully verify X509 certification.\n");

使用Windows Crypto API进行X509证书验证

1 个答案: