SignedXml.CheckSignature fails in .NET 4 but it works in .NET 3.5, 3 or 2

Question

I have a response from a 3-rd party web service. I load an XmlDocument with that response.

  string txt = readStream.ReadToEnd();
  response = new XmlDocumen         


        

Answer 1

public static Boolean VerifyDetachedSignature(string XmlSigFileName)
{   
    // Create a new XML document.
    XmlDocument xmlDocument = new XmlDocument();

    // Load the passed XML file into the document.
    xmlDocument.Load(XmlSigFileName);

    // Find the "Signature" node and create a new XmlNodeList object.
    XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");

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

    // Load the signature node.
    signedXml.LoadXml((XmlElement)nodeList[0]);

    // Check the signature and return the result. 
    return signedXml.CheckSignature();
}