XmlLicenseTransform Class
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XmlLicenseTransform Class

Represents the license transform algorithm used to normalize XrML licenses for signatures.

Namespace:  System.Security.Cryptography.Xml
Assembly:  System.Security (in System.Security.dll)

public class XmlLicenseTransform : Transform

The XmlLicenseTransform class represents the license transform algorithm as defined in the MPEG Rights Extension Language (MPEG REL).

Use the XmlLicenseTransform class to transform XrML licenses for signatures.

The Uniform Resource Identifier (URI) that describes the XmlLicenseTransform class is defined by the XmlLicenseTransformUrl field.

The following code example shows how to validate an XML digital signature using the IRelDecryptor interface and the XmlLicenseTransform class.

public static void CheckSignatureWithEncryptedGrant(string fileName, IRelDecryptor decryptor)
{
    // Create a new XML document.
    XmlDocument xmlDocument = new XmlDocument();
    XmlNamespaceManager nsManager = new XmlNamespaceManager(xmlDocument.NameTable);

    // Format using whitespaces.
    xmlDocument.PreserveWhitespace = true;

    // Load the passed XML file into the document. 
    xmlDocument.Load(fileName);
    nsManager.AddNamespace("dsig", SignedXml.XmlDsigNamespaceUrl);

    // Find the "Signature" node and create a new XmlNodeList object.
    XmlNodeList nodeList = xmlDocument.SelectNodes("//dsig:Signature", nsManager);

    for (int i = 0, count = nodeList.Count; i < count; i++)
    {
        XmlDocument clone = xmlDocument.Clone() as XmlDocument;
        XmlNodeList signatures = clone.SelectNodes("//dsig:Signature", nsManager);

        // Create a new SignedXml object and pass into it the XML document clone.
        SignedXml signedXml = new SignedXml(clone);

        // Load the signature node.
        signedXml.LoadXml((XmlElement)signatures[i]);

        // Set the context for license transform
        Transform trans = ((Reference)signedXml.SignedInfo.References[0]).TransformChain[0];

        if (trans is XmlLicenseTransform)
        {

            // Decryptor is used to decrypt encryptedGrant elements. 
            if (decryptor != null)
                (trans as XmlLicenseTransform).Decryptor = decryptor;
        }

        // Check the signature and display the result. 
        bool result = signedXml.CheckSignature();

        if (result)
            Console.WriteLine("SUCCESS: CheckSignatureWithEncryptedGrant - issuer index #" +
                                            i.ToString());
        else
            Console.WriteLine("FAILURE: CheckSignatureWithEncryptedGrant - issuer index #" +
                                            i.ToString());
    }

}

System.Object
  System.Security.Cryptography.Xml.Transform
    System.Security.Cryptography.Xml.XmlLicenseTransform

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0
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