public static XmlDocument IssueLicense(XmlLicense license, DSACryptoServiceProvider dsa)
{
XmlSerializer serializer = new XmlSerializer(typeof(XmlLicense));
Stream stream = new MemoryStream();
serializer.Serialize(stream, license);
stream.Seek(0, SeekOrigin.Begin);
XmlDocument xml = new XmlDocument();
// Format the document to ignore white spaces.
xml.PreserveWhitespace = false;
xml.Load(stream);
// Create a SignedXml object.
SignedXml signedXml = new SignedXml(xml);
// Add the key to the SignedXml document.
signedXml.SigningKey = dsa;
// Create a reference to be signed.
Reference reference = new Reference();
reference.Uri = "";
// Add a transformation to the reference.
Transform trns = new XmlDsigC14NTransform();
reference.AddTransform(trns);
// Add an enveloped transformation to the reference.
XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
reference.AddTransform(env);
// 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.
xml.DocumentElement.AppendChild(xmlDigitalSignature);
return(xml);
}
public static XmlLicense CheckLicense(string licenseFileName, string publicKeyFileName)
{
try
{
StreamReader sr = new StreamReader(publicKeyFileName);
DSACryptoServiceProvider dsa = LoadKey(sr.ReadToEnd());
sr.Close();
XmlDocument xml = new XmlDocument();
// Format the document to ignore white spaces.
xml.PreserveWhitespace = false;
xml.Load(licenseFileName);
// Create a new SignedXml object and pass it
// the XML document class.
SignedXml signedXml = new SignedXml(xml);
// Find the "Signature" node and create a new
// XmlNodeList object.
XmlNodeList nodeList = xml.GetElementsByTagName("Signature");
// Load the signature node.
signedXml.LoadXml((XmlElement)nodeList[0]);
if (!signedXml.CheckSignature(dsa))
{
throw new Exception("The XML signature of the license is not valid.");
}
xml.DocumentElement.RemoveChild(nodeList[0]);
XmlSerializer serializer = new XmlSerializer(typeof(XmlLicense));
XmlLicense l = (XmlLicense)serializer.Deserialize(new XmlNodeReader(xml));
if (l.Expired < DateTime.Now)
{
throw new Exception("The license is expired.");
}
return(l);
}
catch (Exception e)
{
throw new BadLicense(e.Message);
}
}