public string GetNumeroSerie()
        {
            System.Security.Cryptography.X509Certificates.X509Certificate2 cert = new System.Security.Cryptography.X509Certificates.X509Certificate2(this.PFXArchivo,
                                                                                                                                                     this.PFXContrasena, System.Security.Cryptography.X509Certificates.X509KeyStorageFlags.MachineKeySet);

            return(Certificado.GetSerialNumberString(cert));
        }