Generating XML file with a Digital Signature Certificate - asp.net

Question

I am trying to sign an XML file in C# .NET 4.0 with a private RSA Key generated by OpenSSL.
My source code looks like :
public static void SignXml(String filePath, String certificatePath)
{
CspParameters cspParams1 = new CspParameters();
cspParams1.KeyContainerName = certificatePath;
RSACryptoServiceProvider rsakey = new RSACryptoServiceProvider(cspParams1);
XmlDocument xmlDoc = new XmlDocument();
// Load an XML file into the XmlDocument object.
xmlDoc.PreserveWhitespace = true;
xmlDoc.Load(filePath);
SignedXml signedXml = new SignedXml();
CspParameters cspParams = new CspParameters();
cspParams.KeyContainerName = certificatePath;
// Create a new RSA signing key and save it in the container.
RSACryptoServiceProvider Key = new RSACryptoServiceProvider(cspParams);
// 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);
KeyInfo keyInfo = new KeyInfo();
// Load the X509 certificate.
X509Certificate MSCert = X509Certificate.CreateFromCertFile(certificatePath);
// Load the certificate into a KeyInfoX509Data object
// and add it to the KeyInfo object.
keyInfo.AddClause(new KeyInfoX509Data(MSCert));
keyInfo.AddClause(new RSAKeyValue((RSA)Key));
// Add the KeyInfo object to the SignedXml object.
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.
xmlDoc.DocumentElement.AppendChild(xmlDoc.ImportNode(xmlDigitalSignature, true));
xmlDoc.Save(filePath);
}
I am calling the class (CPSMSXmlGenerator) in my application as a DLL(named DBTBeneficiariesCPSMS) and code for calling it is :
Dim genXml As String = DBTBeneficiariesCPSMS.CPSMSXmlGenerator.getXmlFile1(xml)
'Dim appPath As String = Request.PhysicalApplicationPath
Dim fullPath As String = Server.MapPath("/XML/") + dataSource + ".xml"
lblMessage.Text = fullPath
Dim SwFromFile As StreamWriter = New StreamWriter(fullPath)
SwFromFile.Write(genXml)
SwFromFile.Flush()
SwFromFile.Close()
CPSMSXmlGenerator.SignXml(fullPath, Server.MapPath("/XML/aua.cer"))
Now, the problem is whenever my application runs, it halts at ' Reference.Uri="" ' and an error as :-
Error: An XmlDocument context is required to resolve the Reference Uri .
is displayed, and XML file without digital signature certificate generates.

Answer 1

xmDoc is not passsed to SignedXml. Passing that as param should fix the problem
SignedXml signedXml = new SignedXml(xmlDoc);