DSAKeyValue Class
Assembly: System.Security (in system.security.dll)
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. ' Imports System Imports System.Security.Cryptography Imports System.Security.Cryptography.Xml Imports System.Text Imports System.Xml Class XMLDSIGDetached <STAThread()> _ Overloads Shared Sub Main(args() As String) ' The URI to sign. Dim resourceToSign As String = "http://www.microsoft.com" ' The name of the file to which to save the XML signature. Dim XmlFileName As String = "xmldsig.xml" Try ' Generate a DSA signing key. Dim DSAKey As 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. Dim result As Boolean = VerifyDetachedSignature(XmlFileName) ' Display the results of the signature verification to ' the console. If result Then Console.WriteLine("The XML signature is valid.") Else Console.WriteLine("The XML signature is not valid.") End If Catch e As CryptographicException Console.WriteLine(e.Message) End Try End Sub ' Sign an XML file and save the signature in a new file. Public Shared Sub SignDetachedResource(URIString As String, XmlSigFileName As String, DSAKey As DSA) ' Create a SignedXml object. Dim signedXml As New SignedXml() ' Assign the DSA key to the SignedXml object. signedXml.SigningKey = DSAKey ' Create a reference to be signed. Dim reference As 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). Dim keyInfo As New KeyInfo() keyInfo.AddClause(New DSAKeyValue(CType(DSAKey, DSA))) signedXml.KeyInfo = keyInfo ' Compute the signature. signedXml.ComputeSignature() ' Get the XML representation of the signature and save ' it to an XmlElement object. Dim xmlDigitalSignature As XmlElement = signedXml.GetXml() ' Save the signed XML document to a file specified ' using the passed string. Dim xmltw As New XmlTextWriter(XmlSigFileName, New UTF8Encoding(False)) xmlDigitalSignature.WriteTo(xmltw) xmltw.Close() End Sub ' Verify the signature of an XML file and return the result. Public Shared Function VerifyDetachedSignature(XmlSigFileName As String) As [Boolean] ' Create a new XML document. Dim xmlDocument As New XmlDocument() ' Load the passed XML file into the document. xmlDocument.Load(XmlSigFileName) ' Create a new SignedXMl object. Dim signedXml As New SignedXml() ' Find the "Signature" node and create a new ' XmlNodeList object. Dim nodeList As XmlNodeList = xmlDocument.GetElementsByTagName("Signature") ' Load the signature node. signedXml.LoadXml(CType(nodeList(0), XmlElement)) ' Check the signature and return the result. Return signedXml.CheckSignature() End Function End Class
//
// 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. ' Imports System Imports System.Security.Cryptography Imports System.Security.Cryptography.Xml Imports System.Text Imports System.Xml Public Class SignVerifyEnvelope Overloads Public Shared Sub Main(args() As [String]) Try ' Generate a DSA signing key. Dim DSAKey As 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...") Dim result As Boolean = VerifyXmlFile("SignedExample.xml") ' Display the results of the signature verification to \ ' the console. If result Then Console.WriteLine("The XML signature is valid.") Else Console.WriteLine("The XML signature is not valid.") End If Catch e As CryptographicException Console.WriteLine(e.Message) End Try End Sub ' Sign an XML file and save the signature in a new file. Public Shared Sub SignXmlFile(FileName As String, SignedFileName As String, DSAKey As DSA) ' Create a new XML document. Dim doc As 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. Dim signedXml As New SignedXml(doc) ' Add the DSA key to the SignedXml document. signedXml.SigningKey = DSAKey ' Create a reference to be signed. Dim reference As New Reference() reference.Uri = "" ' Add a transformation to the reference. Dim trns = New XmlDsigC14NTransform() reference.AddTransform(trns) ' Add an enveloped transformation to the reference. Dim env As 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). Dim keyInfo As New KeyInfo() keyInfo.AddClause(New DSAKeyValue(CType(DSAKey, DSA))) signedXml.KeyInfo = keyInfo ' Compute the signature. signedXml.ComputeSignature() ' Get the XML representation of the signature and save ' it to an XmlElement object. Dim xmlDigitalSignature As XmlElement = signedXml.GetXml() ' Append the element to the XML document. doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature, True)) If TypeOf doc.FirstChild Is XmlDeclaration Then doc.RemoveChild(doc.FirstChild) End If ' Save the signed XML document to a file specified ' using the passed string. Dim xmltw As New XmlTextWriter(SignedFileName, New UTF8Encoding(False)) doc.WriteTo(xmltw) xmltw.Close() End Sub ' Verify the signature of an XML file and return the result. Public Shared Function VerifyXmlFile(Name As [String]) As [Boolean] ' Create a new XML document. Dim xmlDocument As 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. Dim signedXml As New SignedXml(xmlDocument) ' Find the "Signature" node and create a new ' XmlNodeList object. Dim nodeList As XmlNodeList = xmlDocument.GetElementsByTagName("Signature") ' Load the signature node. signedXml.LoadXml(CType(nodeList(0), XmlElement)) ' Check the signature and return the result. Return signedXml.CheckSignature() End Function ' Create example data to sign. Public Shared Sub CreateSomeXml(FileName As String) ' Create a new XmlDocument object. Dim document As New XmlDocument() ' Create a new XmlNode object. Dim node As XmlNode = 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. Dim xmltw As New XmlTextWriter(FileName, New UTF8Encoding(False)) document.WriteTo(xmltw) xmltw.Close() End Sub End Class
System.Security.Cryptography.Xml.KeyInfoClause
System.Security.Cryptography.Xml.DSAKeyValue
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.