/// <summary>
        /// Load state from an XML element
        /// </summary>
        /// <param name="xmlElement">XML element containing new state</param>
        public void LoadXml(XmlElement xmlElement)
        {
            XmlNodeList xmlNodeList = null;

            if (xmlElement == null)
            {
                throw new ArgumentNullException("xmlElement");
            }

            if (xmlElement.OwnerDocument != null)
            {
                var xmlNamespaceManager = new XmlNamespaceManager(xmlElement.OwnerDocument.NameTable);
                xmlNamespaceManager.AddNamespace("ds", SignedXml.XmlDsigNamespaceUrl);
                xmlNamespaceManager.AddNamespace("xsd", XadesSignedXml.XadesNamespaceUri);

                xmlNodeList = xmlElement.SelectNodes("xsd:CertDigest", xmlNamespaceManager);
                if (xmlNodeList != null && xmlNodeList.Count == 0)
                {
                    throw new CryptographicException("CertDigest missing");
                }
                _certDigest = new DigestAlgAndValueType("CertDigest");
                if (xmlNodeList != null)
                {
                    _certDigest.LoadXml((XmlElement)xmlNodeList.Item(0));
                }

                xmlNodeList = xmlElement.SelectNodes("xsd:IssuerSerial", xmlNamespaceManager);
            }
            if (xmlNodeList != null && xmlNodeList.Count == 0)
            {
                throw new CryptographicException("IssuerSerial missing");
            }
            _issuerSerial = new IssuerSerial();
            if (xmlNodeList != null)
            {
                _issuerSerial.LoadXml((XmlElement)xmlNodeList.Item(0));
            }
        }
 /// <summary>
 /// Default constructor
 /// </summary>
 public Cert()
 {
     _certDigest   = new DigestAlgAndValueType("CertDigest");
     _issuerSerial = new IssuerSerial();
 }