X509IssuerSerial Structure

Represents the <X509IssuerSerial> element of an XML digital signature.

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

'Declaration
Public Structure X509IssuerSerial
'Usage
Dim instance As X509IssuerSerial

public final class X509IssuerSerial extends ValueType
Not applicable.

The X509IssuerSerial structure represents the <X509IssuerSerial> element of an XML digital signature defined by the XML digital signature specification. The <X509IssuerSerial> element is the subelement of the <X509Data> element that contains an X.509v3 certificate issuer's distinguished name and serial number pair. The distinguished name and serial number pair help identify a specific X.509v3 certificate.

The issuer of an X.509 certificate is the name of the certification authority that issued the certificate. Certification authorities assign each certificate they issue a unique serial number for identification purposes.

Use the X509IssuerSerial structure to specify a certificate issuer's distinguished name and serial number pair when using the KeyInfoX509Data class. You can add an X509IssuerSerial structure to the KeyInfoX509Data class using the IssuerSerials property. Alternatively, you can add string values that represent the X.509 certificate issuer's distinguished name and serial number pair using the AddIssuerSerial method.

For more information about the <X509IssuerSerial> element, see the World Wide Web Consortium (W3C) specification at www.w3.org/TR/xmldsig-core/.

The following code example demonstrates how to sign and verify an XML document using an X.509 certificate from a certificate store. This example saves key information to the signed document using the X509IssuerSerial object.

'
' This example signs an XML file using an
' envelope signature. It then verifies the 
' signed XML.
'
' You must have a certificate with a subject name
' of "CN=XMLDSIG_Test" in the "My" certificate store. 
'
' Run the following command to create a certificate
' and place it in the store.
' makecert -r -pe -n "CN=XMLDSIG_Test" -b 01/01/2005 -e 01/01/2010 -sky signing -ss my
Imports System
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Imports System.Security.Cryptography.X509Certificates
Imports System.Text
Imports System.Xml



Module SignVerifyEnvelope


    Sub Main(ByVal args() As String)

        Dim Certificate As String = "CN=XMLDSIG_Test"

        Try

            ' 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", Certificate)
            Console.WriteLine("XML file signed.")

            If VerifyXmlFile("SignedExample.xml", Certificate) 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.
    Sub SignXmlFile(ByVal FileName As String, ByVal SignedFileName As String, ByVal SubjectName As String)
        If Nothing = FileName Then
            Throw New ArgumentNullException("FileName")
        End If
        If Nothing = SignedFileName Then
            Throw New ArgumentNullException("SignedFileName")
        End If
        If Nothing = SubjectName Then
            Throw New ArgumentNullException("SubjectName")
        End If
        ' Load the certificate from the certificate store.
        Dim cert As X509Certificate2 = GetCertificateBySubject(SubjectName)

        ' 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 key to the SignedXml document. 
        signedXml.SigningKey = cert.PrivateKey

        ' Create a reference to be signed.
        Dim reference As New Reference()
        reference.Uri = ""

        ' 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)

        ' Create a new KeyInfo object.
        Dim keyInfo As New KeyInfo()

        ' Load the certificate into a KeyInfoX509Data object
        ' and add it to the KeyInfo object.
        ' Create an X509IssuerSerial object and add it to the
        ' KeyInfoX509Data object.

        Dim kdata As New KeyInfoX509Data(cert)

        Dim xserial As X509IssuerSerial

        xserial.IssuerName = cert.IssuerName.ToString()
        xserial.SerialNumber = cert.SerialNumber

        kdata.AddIssuerSerial(xserial.IssuerName, xserial.SerialNumber)

        keyInfo.AddClause(kdata)

        ' Add the KeyInfo object to the SignedXml object.
        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))
        Try
            doc.WriteTo(xmltw)

        Finally
            xmltw.Close()
        End Try

    End Sub

    ' Verify the signature of an XML file against an asymetric 
    ' algorithm and return the result.
    Function VerifyXmlFile(ByVal FileName As String, ByVal CertificateSubject As String) As [Boolean]
        ' Check the args.
        If Nothing = FileName Then
            Throw New ArgumentNullException("FileName")
        End If
        If Nothing = CertificateSubject Then
            Throw New ArgumentNullException("CertificateSubject")
        End If
        ' Load the certificate from the store.
        Dim cert As X509Certificate2 = GetCertificateBySubject(CertificateSubject)

        ' Create a new XML document.
        Dim xmlDocument As New XmlDocument()

        ' Load the passed XML file into the document. 
        xmlDocument.Load(FileName)

        ' 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(cert, True)

    End Function



    Function GetCertificateBySubject(ByVal CertificateSubject As String) As X509Certificate2
        ' Check the args.
        If Nothing = CertificateSubject Then
            Throw New ArgumentNullException("CertificateSubject")
        End If

        ' Load the certificate from the certificate store.
        Dim cert As X509Certificate2 = Nothing

        Dim store As New X509Store("My", StoreLocation.CurrentUser)

        Try
            ' Open the store.
            store.Open(OpenFlags.ReadOnly Or OpenFlags.OpenExistingOnly)

            ' Get the certs from the store.
            Dim CertCol As X509Certificate2Collection = store.Certificates

            ' Find the certificate with the specified subject.
            Dim c As X509Certificate2
            For Each c In CertCol
                If c.Subject = CertificateSubject Then
                    cert = c
                    Exit For
                End If
            Next c

            ' Throw an exception of the certificate was not found.
            If cert Is Nothing Then
                Throw New CryptographicException("The certificate could not be found.")
            End If
        Finally
            ' Close the store even if an exception was thrown.
            store.Close()
        End Try

        Return cert

    End Function


    ' Create example data to sign.
    Sub CreateSomeXml(ByVal FileName As String)
        ' Check the args.
        If Nothing = FileName Then
            Throw New ArgumentNullException("FileName")
        End If
        ' 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))
        Try
            document.WriteTo(xmltw)

        Finally
            xmltw.Close()
        End Try

    End Sub
End Module
' This code example displays the following to the console:
'
' New XML file created.
' XML file signed.
' The XML signature is valid.

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

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