iTextSharp.text.pdf.security.MakeXmlSignature.Sign C# (CSharp) Метод

        private static void Sign(XmlElement signature, IXmlLocator xmlLocator, IExternalSignature externalSignature, 
                                 List<XmlElement> references, XmlElement dsObject, KeyInfoClause keyInfo) {

            XmlDocument originalDoc = xmlLocator.GetDocument();

            if (signature == null)
                throw new InvalidOperationException();

            XmlElement signedInfo = originalDoc.CreateElement("SignedInfo", SecurityConstants.XMLDSIG_URI);
            signature.AppendChild(signedInfo);

            XmlElement canonicalizationMethod = originalDoc.CreateElement("CanonicalizationMethod", SecurityConstants.XMLDSIG_URI);
            canonicalizationMethod.SetAttribute("Algorithm", SecurityConstants.XMLDSIG_URI_C14N);
            signedInfo.AppendChild(canonicalizationMethod);

            XmlElement signatureMethod = originalDoc.CreateElement("SignatureMethod", SecurityConstants.XMLDSIG_URI);
            if(externalSignature.GetEncryptionAlgorithm().Equals(SecurityConstants.RSA))
                signatureMethod.SetAttribute("Algorithm", SecurityConstants.XMLDSIG_URI_RSA_SHA1);
            else if(externalSignature.GetEncryptionAlgorithm().Equals(SecurityConstants.DSA))
                signatureMethod.SetAttribute("Algorithm", SecurityConstants.XMLDSIG_URI_DSA_SHA1);
            signedInfo.AppendChild(signatureMethod);

            foreach (XmlElement reference in references)
                signedInfo.AppendChild(reference);    
            
            //if append Signature to original document upper - reference digest will be incorrect.
            originalDoc.DocumentElement.AppendChild(signature);

            XmlElement signedInfoDigest = (XmlElement)signedInfo.CloneNode(true);
            NormalizeNamespaces(signedInfo.CreateNavigator(), signedInfoDigest.CreateNavigator());
            XmlDocument signedInfoDoc = new XmlDocument(originalDoc.NameTable);
            signedInfoDoc.LoadXml(signedInfoDigest.OuterXml);
            byte[] byteRange = CalculateC14nByteRange(signedInfoDoc);

            //Sign with ExternalSignature
            String valueBase64 = Convert.ToBase64String(externalSignature.Sign(byteRange));

            XmlElement signatureValue = originalDoc.CreateElement("SignatureValue", SecurityConstants.XMLDSIG_URI);
            signatureValue.AppendChild(originalDoc.CreateTextNode(valueBase64));

            signature.AppendChild(signatureValue);

            if(keyInfo != null) {
                XmlElement keyInfoElement = originalDoc.CreateElement("KeyInfo", SecurityConstants.XMLDSIG_URI);
                keyInfoElement.AppendChild(originalDoc.ImportNode(keyInfo.GetXml(), true));
                signature.AppendChild(keyInfoElement);
            }

            if (dsObject != null)
                signature.AppendChild(dsObject);

            xmlLocator.SetDocument(originalDoc);
        }
    }