extern static bool PFXExportCertStoreEx(
     CertificateStoreHandle hStore,
     IntPtr pPFX,
     //IntPtr szPassword,
     string password,
     IntPtr pvReserved,
     PfxExportFlags dwFlags);
 extern static bool PFXExportCertStoreEx(
                                             CertificateStoreHandle hStore,
                                             IntPtr pPFX,
     //IntPtr szPassword,
                                             string password,
                                             IntPtr pvReserved,
                                             PfxExportFlags dwFlags);
 internal static extern bool PFXExportCertStoreEx(
     CertificateStoreHandle hStore,
     IntPtr pPFX,
     IntPtr szPassword,
     IntPtr pvReserved,
     PfxExportFlags dwFlags);