After MS16-035 security update this code from MSDN doesn't work.
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//
// This example signs an XML file using an
// envelope signature. It then verifies the
// signed XML.
//
using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;
public class SignVerifyEnvelope
{
public static void Main(String[] args)
{
// Generate a signing key.
RSACryptoServiceProvider Key = new RSACryptoServiceProvider();
string xsl = @"
<xs:transform xmlns:xs='http://www.w3.org/1999/XSL/Transform' version='1.0'>
<xs:template match='/'>
<xs:apply-templates/>
</xs:template>
<xs:template match='ElementToTransform'>
<transformedElement/>
</xs:template>
</xs:transform>";
try
{
// Create an XML file to sign.
CreateSomeXml("Example.xml");
Console.WriteLine("New XML file created.");
// Sign the XML that was just created and save it in a
// new file.
SignXmlFile("Example.xml", "SignedExample.xml", Key, xsl);
Console.WriteLine("XML file signed.");
// Verify the signature of the signed XML.
Console.WriteLine("Verifying signature...");
bool result = VerifyXmlFile("SignedExample.xml");
// Display the results of the signature verification to \
// the console.
if (result)
{
Console.WriteLine("The XML signature is valid.");
}
else
{
Console.WriteLine("The XML signature is not valid.");
}
}
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
}
finally
{
Key.Clear();
}
Console.ReadLine();
}
// Sign an XML file and save the signature in a new file.
public static void SignXmlFile(string FileName, string SignedFileName, RSA Key, string XSLString)
{
// Create a new XML document.
XmlDocument doc = new XmlDocument();
// Format the document to ignore white spaces.
doc.PreserveWhitespace = false;
// Load the passed XML file using it's name.
doc.Load(new XmlTextReader(FileName));
// Create a SignedXml object.
SignedXml signedXml = new SignedXml(doc);
// 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);
// Create an XmlDsigXPathTransform object using
// the helper method 'CreateXPathTransform' defined
// later in this sample.
XmlDsigXsltTransform XsltTransform = CreateXsltTransform(XSLString);
// Add the transform to the reference.
reference.AddTransform(XsltTransform);
// Add the reference to the SignedXml object.
signedXml.AddReference(reference);
// Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
KeyInfo keyInfo = new KeyInfo();
keyInfo.AddClause(new RSAKeyValue((RSA)Key));
signedXml.KeyInfo = keyInfo;
// 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.
doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature, true));
// Save the signed XML document to a file specified
// using the passed string.
XmlTextWriter xmltw = new XmlTextWriter(SignedFileName, new UTF8Encoding(false));
doc.WriteTo(xmltw);
xmltw.Close();
}
// Verify the signature of an XML file and return the result.
public static Boolean VerifyXmlFile(String Name)
{
// Create a new XML document.
XmlDocument xmlDocument = new XmlDocument();
// Format using white spaces.
xmlDocument.PreserveWhitespace = true;
// Load the passed XML file into the document.
xmlDocument.Load(Name);
// Create a new SignedXml object and pass it
// the XML document class.
SignedXml signedXml = new SignedXml(xmlDocument);
// Find the "Signature" node and create a new
// XmlNodeList object.
XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");
// Load the signature node.
signedXml.LoadXml((XmlElement)nodeList[0]);
// Check the signature and return the result.
return signedXml.CheckSignature();
}
// Create the XML that represents the transform.
public static XmlDsigXsltTransform CreateXsltTransform(string xsl)
{
XmlDocument doc = new XmlDocument();
doc.LoadXml(xsl);
XmlDsigXsltTransform xform = new XmlDsigXsltTransform();
xform.LoadInnerXml(doc.ChildNodes);
return xform;
}
// Create example data to sign.
public static void CreateSomeXml(string FileName)
{
// Create a new XmlDocument object.
XmlDocument document = new XmlDocument();
// Create a new XmlNode object.
XmlNode node = document.CreateNode(XmlNodeType.Element, "", "MyXML", "Don't_Sign");
// Append the node to the document.
document.AppendChild(node);
// Create a new XmlNode object.
XmlNode subnode = document.CreateNode(XmlNodeType.Element, "", "ElementToTransform", "Sign");
// Add some text to the node.
subnode.InnerText = "Here is some data to sign.";
// Append the node to the document.
document.DocumentElement.AppendChild(subnode);
// Save the XML document to the file name specified.
XmlTextWriter xmltw = new XmlTextWriter(FileName, new UTF8Encoding(false));
document.WriteTo(xmltw);
xmltw.Close();
}
}