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

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

            xmlNamespaceManager = new XmlNamespaceManager(xmlElement.OwnerDocument.NameTable);
            xmlNamespaceManager.AddNamespace("xsd", XadesSignedXml.XadesNamespaceUri);

            xmlNodeList = xmlElement.SelectNodes("xsd:OCSPIdentifier", xmlNamespaceManager);
            if (xmlNodeList.Count == 0)
            {
                throw new CryptographicException("OCSPIdentifier missing");
            }
            this.ocspIdentifier = new OCSPIdentifier();
            this.ocspIdentifier.LoadXml((XmlElement)xmlNodeList.Item(0));

            xmlNodeList = xmlElement.SelectNodes("xsd:DigestAlgAndValue", xmlNamespaceManager);
            if (xmlNodeList.Count == 0)
            {
                this.digestAlgAndValue = null;
            }
            else
            {
                this.digestAlgAndValue = new DigestAlgAndValueType("DigestAlgAndValue");
                this.digestAlgAndValue.LoadXml((XmlElement)xmlNodeList.Item(0));
            }
        }
 /// <summary>
 /// Default constructor
 /// </summary>
 public OCSPRef()
 {
     this.ocspIdentifier    = new OCSPIdentifier();
     this.digestAlgAndValue = new DigestAlgAndValueType("DigestAlgAndValue");
 }