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DSAKeyValue Class

Represents the DSA private key of the <KeyInfo> element.

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

public class DSAKeyValue : KeyInfoClause
public class DSAKeyValue extends KeyInfoClause
public class DSAKeyValue extends KeyInfoClause
Not applicable.

The KeyInfo class represents the <KeyInfo> element, which contains a DSA public key.

Use DSAKeyValue to identify the public key that corresponds to the DSA private key that was used to create the digital signature.

If a key is not explicitly supplied to the constructor, a new DSA key pair is randomly generated.

The DSAKeyValue class is used with XML signatures. For more information about the W3C specification, see http://www.w3.org/TR/xmldsig-core/.

The following code example demonstrates how to use the DSAKeyValue class in XML encryption to create a detached signature.

//
// This example signs a file specified by a URI 
// using a detached signature. It then verifies  
// the signed XML.
//

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;



class XMLDSIGDetached
{
	
    [STAThread]
    static void Main(string[] args)
    {
        // The URI to sign.
        string resourceToSign = "http://www.microsoft.com";
		
        // The name of the file to which to save the XML signature.
        string XmlFileName = "xmldsig.xml";

        try
        {

            // Generate a DSA signing key.
            DSACryptoServiceProvider DSAKey = new DSACryptoServiceProvider();

            Console.WriteLine("Signing: {0}", resourceToSign);

            // Sign the detached resourceand save the signature in an XML file.
            SignDetachedResource(resourceToSign, XmlFileName, DSAKey);

            Console.WriteLine("XML signature was succesfully computed and saved to {0}.", XmlFileName);

            // Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...");

            //Verify the XML signature in the XML file.
            bool result = VerifyDetachedSignature(XmlFileName);

            // 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.
    public static void SignDetachedResource(string URIString, string XmlSigFileName, DSA DSAKey)
    {
        // Create a SignedXml object.
        SignedXml signedXml = new SignedXml();

        // Assign the DSA key to the SignedXml object.
        signedXml.SigningKey = DSAKey;

        // Create a reference to be signed.
        Reference reference = new Reference();

        // Add the passed URI to the reference object.
        reference.Uri = URIString;
		
        // Add the reference to the SignedXml object.
        signedXml.AddReference(reference);

        // Add a DSAKeyValue to the KeyInfo (optional; helps recipient find key to validate).
        KeyInfo keyInfo = new KeyInfo();
        keyInfo.AddClause(new DSAKeyValue((DSA)DSAKey));	
        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();

        // Save the signed XML document to a file specified
        // using the passed string.
        XmlTextWriter xmltw = new XmlTextWriter(XmlSigFileName, new UTF8Encoding(false));
        xmlDigitalSignature.WriteTo(xmltw);
        xmltw.Close();
    }
    // Verify the signature of an XML file and return the result.
    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);
	
        // Create a new SignedXMl object.
        SignedXml signedXml = new SignedXml();

        // 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();
    }
}

//
// This example signs a file specified by a URI 
// using a detached signature. It then verifies  
// the signed XML.
//
import System.*;
import System.Security.Cryptography.*;
import System.Security.Cryptography.Xml.*;
import System.Text.*;
import System.Xml.*;

class XMLDSIGDetached
{
    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        // The URI to sign.
        String resourceToSign = "http://www.microsoft.com";
        
        // The name of the file to which to save the XML signature.
        String xmlFileName = "xmldsig.xml";
        
        try {
            // Generate a DSA signing key.
            DSACryptoServiceProvider dsaKey =  new DSACryptoServiceProvider();
            
            Console.WriteLine("Signing: {0}", resourceToSign);
            
            // Sign the detached resourceand save the signature in an XML file.
            SignDetachedResource(resourceToSign, xmlFileName, dsaKey);
            
            Console.WriteLine("XML signature was succesfully computed " 
                + "and saved to {0}.", xmlFileName);
            
            // Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...");
            
            // Verify the XML signature in the XML file.
            boolean result = 
                VerifyDetachedSignature(xmlFileName).booleanValue();
            
            // 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.get_Message());
        }
    } //main 

    // Sign an XML file and save the signature in a new file.
    public static void SignDetachedResource(String uriString, 
        String xmlSigFileName, DSA dsaKey) 
    {
        // Create a SignedXml object.
        SignedXml signedXml =  new SignedXml();
        
        // Assign the DSA key to the SignedXml object.
        signedXml.set_SigningKey ( dsaKey);
        
        // Create a reference to be signed.
        Reference reference =  new Reference();
        
        // Add the passed URI to the reference object.
        reference.set_Uri ( uriString);
        
        // Add a transformation if the URI is an XML file.
        if (uriString.EndsWith("xml")) {
            reference.AddTransform(new XmlDsigC14NTransform());
        }
        
        // Add the reference to the SignedXml object.
        signedXml.AddReference(reference);
        
        // Add a DSAKeyValue to the KeyInfo (optional; 
        // helps recipient find key to validate).
        KeyInfo keyInfo =  new KeyInfo();
        keyInfo.AddClause(new DSAKeyValue(((DSA)(dsaKey))));
        signedXml.set_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();
        
        // Save the signed XML document to a file specified
        // using the passed string.
        XmlTextWriter xmlTW =  
            new XmlTextWriter(xmlSigFileName, new UTF8Encoding(false));
        xmlDigitalSignature.WriteTo(xmlTW);
        xmlTW.Close();
    } //SignDetachedResource   

    // Verify the signature of an XML file and return the result.
    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);
        
        // Create a new SignedXMl object.
        SignedXml signedXml =  new SignedXml();
        
        // Find the "Signature" node and create a new
        // XmlNodeList object.
        XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");
        
        // Load the signature node.
        signedXml.LoadXml(((XmlElement)(nodeList.get_ItemOf(0))));
        
        // Check the signature and return the result.
        return new Boolean(signedXml.CheckSignature()) ;
    } //VerifyDetachedSignature
} //XMLDSIGDetached

The following code example demonstrates how to use the DSAKeyValue class in XML encryption to create an envelope signature.

//
// This example signs an XML file using an
// envelope signature. It then verifies the 
// signed XML.
//
using System;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;

public class SignVerifyEnvelope
{

    public static void Main(String[] args)
    {
        try
        {
            // Generate a DSA signing key.
            DSACryptoServiceProvider DSAKey = new DSACryptoServiceProvider();

            // Create an XML file to sign.
            CreateSomeXml("Example.xml");
            Console.WriteLine("New XML file created."); 

            // Sign the XML that was just created and save it in a 
            // new file.
            SignXmlFile("Example.xml", "SignedExample.xml", DSAKey);
            Console.WriteLine("XML file signed."); 

            // Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...");
            bool result = VerifyXmlFile("SignedExample.xml");

            // 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.
    public static void SignXmlFile(string FileName, string SignedFileName, DSA DSAKey)
    {
        // Create a new XML document.
        XmlDocument doc = new XmlDocument();

        // Format the document to ignore white spaces.
        doc.PreserveWhitespace = false;

        // Load the passed XML file using it's name.
        doc.Load(new XmlTextReader(FileName));

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

        // Add the DSA key to the SignedXml document. 
        signedXml.SigningKey = DSAKey;

        // 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);

		
        // Add a DSAKeyValue to the KeyInfo (optional; helps recipient find key to validate).
        KeyInfo keyInfo = new KeyInfo();
        keyInfo.AddClause(new DSAKeyValue((DSA)DSAKey));
        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.
        doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature, true));
		
		
        if (doc.FirstChild is XmlDeclaration)  
        {
            doc.RemoveChild(doc.FirstChild);
        }

        // 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 and return the result.
    public static Boolean VerifyXmlFile(String Name)
    {
        // Create a new XML document.
        XmlDocument xmlDocument = new XmlDocument();

        // Format using white spaces.
        xmlDocument.PreserveWhitespace = true;

        // 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();
    }

    // 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");
		
        // Add some text to the node.
        node.InnerText = "Example text to be signed.";

        // 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();
    }
}

System.Object
   System.Security.Cryptography.Xml.KeyInfoClause
    System.Security.Cryptography.Xml.DSAKeyValue

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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