Visual Basic Source: setRef.frm

 

[This sample code uses features that were implemented in MSXML 5.0 for Microsoft Office Applications. XML digital signatures are not supported in MXSML 6.0 and later.]

Dim xmldoc As New DOMDocument50
Dim xmldsig As New MXDigitalSignature50
Dim dsigKey As IXMLDSigKey
Dim dataObj As IXMLDOMNode
Dim outfile
Dim provType, keyContainer

Const DSIGNS = "xmlns:ds='http://www.w3.org/2000/09/xmldsig#'"
Const PROV_RSA_FULL = 1
' Change this key container name to your own if necessary.
Const RSA_KEY = "MyRSAFullKeys"
Const infile = "signature_template.setRef.rsa.xml"
Const outfile2 = "signature.setRef.rsa.obj2.xml"
Const outfile1 = "signature.setRef.rsa.obj1.xml"
    

Private Function WriteLine(ByVal str As String)
    Text1.Text = Text1.Text + str + vbNewLine
End Function
Private Function writeClear()
    Text1.Text = ""
End Function

Private Function LoadXML(ByVal file As String)
    ' Read the input XML file and display the content in the text3.
    Path = App.Path + "\" + file
    xmldoc.async = False
    xmldoc.preserveWhiteSpace = True
    xmldoc.validateOnParse = False
    xmldoc.resolveExternals = False
    If xmldoc.Load(Path) = False Then
        WriteLine "Can't load " + Path
        WriteLine "Reason: " + xmldoc.parseError.reason
        LoadXML = False
        Exit Function
    End If
    xmldoc.setProperty "SelectionNamespaces", DSIGNS
    LoadXML = True
End Function
Private Function SignXML(objID As String)
    If xmldoc.xml = "" Then
        WriteLine "Invalid signature template."
        SignXML = False
        Exit Function
    End If
    
    If keyContainer = "" Then
        WriteLine "Invalid key container."
        SignXML = False
        Exit Function
    End If
    
    Set xmldsig.signature = xmldoc.selectSingleNode(".//ds:Signature")
    Set oKey = xmldsig.createKeyFromCSP(provType, "", keyContainer, 0)
    If oKey Is Nothing Then
        WriteLine "Invalid key"
        SignXML = False
        Exit Function
    End If
    
    xpath = ".//ds:Object[@Id='" + objID + "']"
    Set dataObj = xmldoc.selectSingleNode(xpath)
    xmldsig.setReferenceData "#obj2", dataObj

    Set oSignedKey = xmldsig.Sign(oKey, KEYVALUE)
    If oSignedKey Is Nothing Then
        WriteLine "sign failed."
        SignXML = False
        Exit Function
    End If
         
    WriteLine "The specified data was signed successfully."
    WriteLine "Resultant signature: " + vbNewLine
    WriteLine xmldoc.xml
    
    output = App.Path + "\" + outfile
    xmldoc.Save (output)
    SignXML = True
End Function

Private Function VerifyXML(ByVal objID As String)
    If xmldoc.xml = "" Then
        WriteLine "Invalid XML signature file."
        VerifyXML = False
        Exit Function
    End If
        
    Set signature = xmldoc.selectSingleNode(".//ds:Signature")
    If signature Is Nothing Then
        WriteLine "Invalid <Signature> element"
        VerifyXML = False
        Exit Function
    End If
    Set xmldsig.signature = signature
    
    Set oKeyInfo = xmldoc.selectSingleNode(".//ds:KeyInfo/ds:KeyValue")
    If oKeyInfo Is Nothing Then
        WriteLine "Invalid <KeyInfo> element."
        VerifyXML = False
        Exit Function
    End If
    Set oPubKey = xmldsig.createKeyFromNode(oKeyInfo)
    If oPubKey Is Nothing Then
        WriteLine "Can't generate public key for verification."
        VerifyXML = False
        Exit Function
    End If
    
    xpath = ".//ds:Object[@Id='" + objID + "']"
    Set dataObj = xmldoc.selectSingleNode(xpath)
    xmldsig.setReferenceData "#obj2", dataObj

    Set oVerifiedKey = xmldsig.Verify(oPubKey)
    If oVerifiedKey Is Nothing Then
        WriteLine "Signature not verified."
    End If
         
    WriteLine "Signature verified on the data."
    VerifyXML = True
End Function

Private Sub Form_Load()
    'Set text box to use form to determine its width
    'and height when form is loaded
    Text1.Left = 100
    Text1.Top = 100
    Text1.Width = Form1.Width - 350
    Text1.Height = Form1.Height - 750

    provType = PROV_RSA_FULL
    keyContainer = RSA_KEY
    writeClear
    
    WriteLine "Attempting to sign the object of 'obj1'." + vbNewLine
    outfile = outfile1
    If LoadXML(infile) = True Then
       SignXML "obj1"
    End If
    
    If LoadXML(outfile) = True Then
        VerifyXML "obj1"
    End If
        
    WriteLine vbNewLine
    WriteLine "Attempting to sign the object of 'obj2'." + vbNewLine
    outfile = outfile2
    If LoadXML(infile) = True Then
        SignXML "obj2"
    End If
    
    If LoadXML(outfile) = True Then
        VerifyXML "obj2"
    End If
    
    
End Sub

Private Sub Form_Resize()
    'Set text box to use form in determining its width and height
    'when form is resized
    Text1.Width = Form1.Width - 350
    Text1.Height = Form1.Height - 750
End Sub

Try It!

1. Ensure that you have completed all the procedures in Getting Started with XML Digital Signatures.

2. Copy the XML signature template from Resource: signature_template.setRef.rsa.xml, and paste it into a text editor. Save it to a file named signature_template.setRef.rsa.xml.

3. Create a Standard EXE project in Visual Basic. Save the empty project as setRef.vbp to the same directory where you saved signature_template.setRef.rsa.xml. Name the form file setRef.frm.

4. Create a reference to MSXML 5.0 for Microsoft Office Applications. To do this, select References... from the Project menu, then check the box for Microsoft XML, v5.0.

5. Double click on the TextBox icon from the tools menu. A TextBox control will appear on the project's form named "Text1". Select the Text1 control and and in the Properties window, modify the following settings: select "2 - Vertical" as the value for the ScrollBars property and set the value of the MultiLine property to True.

6. Copy the Visual Basic code listing above, and paste it into the code editor to replace whatever code is already there.

7. Execute the code by selecting Start from the Run menu.

8. Verify that your output is similar to that listed in the Output topic.