System.Xml.XmlDocument.ImportNode C# (CSharp) Method

        public virtual XmlNode ImportNode(XmlNode node, bool deep)
        {
            return ImportNodeInternal(node, deep);
        }

        // Sign an XML file.  
        // This document cannot be verified unless the verifying  
        // code has the key with which it was signed. 
        public static void SignXml(XmlDocument xmlDoc, RSA Key)
        {
            // Check arguments. 
            if (xmlDoc == null)
                throw new ArgumentException("xmlDoc");
            if (Key == null)
                throw new ArgumentException("Key");

            // Create a SignedXml object.
            SignedXml signedXml = new SignedXml(xmlDoc);

            // Add the key to the SignedXml document.
            signedXml.SigningKey = Key;

            // Create a reference to be signed.
            Reference reference = new Reference();
            reference.Uri = "";

            // Add an enveloped transformation to the reference.
            XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
            reference.AddTransform(env);

            // Add the reference to the SignedXml object.
            signedXml.AddReference(reference);

            // Compute the signature.
            signedXml.ComputeSignature();

            // Get the XML representation of the signature and save 
            // it to an XmlElement object.
            XmlElement xmlDigitalSignature = signedXml.GetXml();

            // Append the element to the XML document.
            xmlDoc.DocumentElement.AppendChild(xmlDoc.ImportNode(xmlDigitalSignature, true));
        }