{

class Program

{

private static string SIGNATURE_ALG = "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256";

private static string SIGNATURE_DIG = "http://www.w3.org/2001/04/xmlenc#sha256";

private static string CERT_FILE = "somecertificate.pfx";

public static void Main(String[] args)

{

try

{

CryptoConfig.AddAlgorithm(typeof(RSAPKCS1SHA256SignatureDescription), SIGNATURE_ALG);

// Generate a signing key.

RSACryptoServiceProvider Key = new RSACryptoServiceProvider();

// Create an XML file to sign.

CreateSomeXml("Example.xml");

// Sign the XML that was just created and save it in a

// new file.

SignXmlFile("Example.xml", "signedExample.xml", Key);

// Use below to use certificate.

// Verify the signature of the signed XML.

bool result = VerifyXmlFile("SignedExample.xml", Key);

// 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);

}

}

// Sign an XML file and save the signature in a new file. This method does not

// save the public key within the XML file. This file cannot be verified unless

// the verifying code has the key with which it was signed.

public static void SignXmlFile(string FileName, string SignedFileName, RSA Key)

{

// Create a new XML document.

XmlDocument doc = new XmlDocument();

// Load the passed XML file using its name.

doc.Load(new XmlTextReader(FileName));

// Create a SignedXml object.

SignedXml signedXml = new SignedXml(doc);

// Add the key to the SignedXml document using ceritificate file.

//X509Certificate2 certificate;

//using (FileStream fs =

// File.Open(CERT_FILE, FileMode.Open))

//using (BinaryReader br = new BinaryReader(fs))

//{

// certificate =

// new X509Certificate2(

// br.ReadBytes((int)br.BaseStream.Length), "demo");

//}

//signedXml.SigningKey = certificate.PrivateKey;

// Add the key to the SignedXml document using pre-shared key.

signedXml.SigningKey = Key;

signedXml.SignedInfo.SignatureMethod = SIGNATURE_ALG;

// Create a reference to be signed.

Reference reference = new Reference();

reference.Uri = "";

// Add an enveloped transformation to the reference.

reference.AddTransform(new XmlDsigEnvelopedSignatureTransform());

reference.AddTransform(new XmlDsigExcC14NTransform());

reference.DigestMethod = SIGNATURE_DIG;

// If you are using certificate, use code below,

// and pass the certificate as parameter.

//KeyInfo keyInfo = new KeyInfo();

//KeyInfoX509Data keyInfoData = new KeyInfoX509Data(certificate);

//keyInfo.AddClause(keyInfoData);

//signedXml.KeyInfo = keyInfo;

// 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.

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 against an asymetric

// algorithm and return the result.

public static Boolean VerifyXmlFile(String Name, RSA Key)

{

// Create a new XML document.

XmlDocument xmlDocument = new XmlDocument();

// 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(Key);

}

// Verify the signature of an XML file from its certificate

// in the signature key info.

public static Boolean VerifyXmlFileFromCert(String Name)

{

// Create a new XML document.

XmlDocument xmlDocument = new XmlDocument();

// Load the passed XML file into the document.

xmlDocument.Load(Name);

SignedXml signedXml = new SignedXml(xmlDocument);

// Load the signature node.

signedXml.LoadXml((XmlElement)xmlDocument.GetElementsByTagName("Signature")[0]);

// Get certificate key info from XML

X509Certificate2 certificate = null;

foreach (KeyInfoClause clause in signedXml.KeyInfo)

{

if (clause is KeyInfoX509Data)

{

if (((KeyInfoX509Data)clause).Certificates.Count > 0)

{

certificate =

(X509Certificate2)((KeyInfoX509Data)clause).Certificates[0];

}

}

}

// Check the signature and return the result.

return signedXml.CheckSignature(certificate, true);

}

// 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, "", "MyElement", "samples");

// Append the node to the document.

document.AppendChild(node);

// Save the XML document to the file name specified.

XmlTextWriter xmltw = new XmlTextWriter(FileName, new UTF8Encoding(false));

document.WriteTo(xmltw);

xmltw.Close();

}

}