Проверка удостоверяющей подписи

    HCRYPTMSG hMsg = CryptMsgOpenToDecode(
        X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
        0, 0, 0, 0, 0);
    if (!hMsg)
    {
        std::cout << "CryptMsgOpenToDecode() failed" << std::endl;
        return;
    }

    if (!CryptMsgUpdate(
        hMsg,
        &storeBlob[0],
        storeBlob.size(),
        TRUE))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgUpdate() failed" << std::endl;
        return;
    }

    HCERTSTORE hMsgStore = CertOpenStore(
        CERT_STORE_PROV_MSG,
        X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
        0, 0, hMsg);
    if (!hMsgStore) {
        std::cout << "CertOpenStore() failed" << std::endl;
        return;
    }

    if (!CryptMsgClose(hMsg))
    {
        std::cout << "CryptMsgClose() failed" << std::endl;
        return;
    }

    hMsg = CryptMsgOpenToDecode(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
        0,0,0,0,0);
    if(!hMsg)
    {
        std::cout << "CryptMsgOpenToDecode() failed" << std::endl;
        return;
    }

    if(!CryptMsgUpdate(hMsg,&message[0],(DWORD)message.size(),TRUE))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgUpdate() failed" << std::endl;
        return;
    }

    DWORD size = 0;
    if(!CryptMsgGetParam(hMsg,CMSG_ENCODED_SIGNER,0,0,&size))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgGetParam() failed" << std::endl;
        return;
    }
    std::vector<BYTE> encodedSigner(size);
    if(!CryptMsgGetParam(hMsg,CMSG_ENCODED_SIGNER,0,&encodedSigner[0],&size))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgGetParam() failed" << std::endl;
        return;
    }

    size = 0;
    if(!CryptMsgGetParam(hMsg,CMSG_SIGNER_UNAUTH_ATTR_PARAM,0,0,&size))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgGetParam() failed" << std::endl;
        return;
    }
    std::vector<BYTE> unsignedAttrsData(size);
    if(!CryptMsgGetParam(hMsg,CMSG_SIGNER_UNAUTH_ATTR_PARAM,0,&unsignedAttrsData[0],&size))
    {
        CryptMsgClose(hMsg);
        std::cout << "CryptMsgGetParam() failed" << std::endl;
        return;
    }
    PCRYPT_ATTRIBUTES pAttrs = reinterpret_cast<PCRYPT_ATTRIBUTES>(&unsignedAttrsData[0]);

    std::vector<BYTE> countersignature;
    for( DWORD i = 0; i < pAttrs->cAttr; ++i)
    {
        if( std::string(szOID_RSA_counterSign) == pAttrs->rgAttr[i].pszObjId )
        {
            if(!pAttrs->rgAttr[i].cValue)
            {
                CryptMsgClose(hMsg);
                std::cout << "No values in countersignature attribute." << std::endl;
                return;
            }
            countersignature.resize(pAttrs->rgAttr[i].rgValue[0].cbData);
            memcpy(&countersignature[0],
                pAttrs->rgAttr[i].rgValue[0].pbData,countersignature.size());
            break;
        }
    }
    if(countersignature.empty())
    {
        CryptMsgClose(hMsg);
        std::cout << "No countersignature found in message." << std::endl;
        return;
    }

    CADES_VERIFICATION_PARA counterSignVerifyPara = { sizeof(counterSignVerifyPara) };
    counterSignVerifyPara.dwCadesType = CADES_BES;
    counterSignVerifyPara.hStore = hMsgStore;

    if (!CadesMsgVerifyCountersignatureEncoded(0, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
        &encodedSigner[0], (DWORD)encodedSigner.size(),
        &countersignature[0], (DWORD)countersignature.size(), 0,
        &counterSignVerifyPara, 0))
    {
        CryptMsgClose(hMsg);
        std::cout << "Countersignature is not verified." << std::endl;
        return;
    }
    else
        std::cout << "Countersignature is valid." << std::endl;

    if(!CryptMsgClose(hMsg))
    {
        std::cout << "CryptMsgGetParam() failed" << std::endl;
        return;
    }
    // Конец проверки удостоверяющей подписи