// Поиск сертификата в хранилище
void FoundCertificateInStore(ICertificate2Ptr iCert)
{
    IStorePtr pIStore;
    ICertificates2Ptr pICertificates;
    ICertificates2Ptr pICertificatesFound;
    VARIANT varCriteria;

    pIStore = CreateOleObject("CAPICOM.Store.3");

    if (FAILED(pIStore->Open(CAPICOM_STORE_LOCATION::CAPICOM_CURRENT_USER_STORE,
                             L"My",
                             CAPICOM_STORE_OPEN_MODE::CAPICOM_STORE_OPEN_READ_ONLY)))
    {
        ShowMessage("Ошибка открытия хранилища сертификатов");
        return;
    }

    //Поиск

    pICertificates = pIStore->Certificates;

    varCriteria.vt = VT_I1;
    varCriteria.pcVal = "c01134ee90d8fd41cf9fdc1b99644038c6e5bf21";

    pICertificatesFound = pICertificates->Find(CAPICOM_CERTIFICATE_FIND_TYPE::CAPICOM_CERTIFICATE_FIND_SHA1_HASH,
                         varCriteria,
                         false);

    ShowMessage(pICertificatesFound->Count);
}

FindType   : CAPICOM_CERTIFICATE_FIND_TYPE;
varCriteria: OleVariant

FindType:=CAPICOM_CERTIFICATE_FIND_SHA1_HASH; // = 0
varCriteria:='C01134EE90D8FD41CF9FDC1B99644038C6E5BF21';

  Store := CoStore.Create;
  Store.Open( CAPICOM_CURRENT_USER_STORE, CAPICOM_MY_STORE, CAPICOM_STORE_OPEN_READ_ONLY);
  Certs := Store.Certificates.Find( FindType, varCriteria, false );
  //Certs.Count - количество найденных сертификатов