Visual Basic Source: verify.frm
Dim xmldoc As New DOMDocument50 Dim xmldsig As New MXDigitalSignature50 Dim dsigKey As IXMLDSigKey Dim dataObj As IXMLDOMNode Const DSIGNS = "xmlns:ds='http://www.w3.org/2000/09/xmldsig#'" Const INFILE = "signature.verify.dsa.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 input xml file and display the content in the text1. 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 Set xmldsig.signature = xmldoc.selectSingleNode(".//ds:Signature") LoadXML = True End Function Private Function VerifyXML() If xmldsig.signature Is Nothing Then WriteLine "Invalid signature." VerifyXML = False Exit Function End If 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 Set oVerifiedKey = xmldsig.verify(oPubKey) If oVerifiedKey Is Nothing Then WriteLine "Signature not verified." End If WriteLine "Signature verified." VerifyXML = True End Function Private Sub Form_Load() writeClear WriteLine "Verifyin signature." If LoadXML(INFILE) = True Then VerifyXML End If End Sub
Try It!
- Ensure that you have completed all the procedures in Getting Started with XML Digital Signatures.
- Copy the XML signature resource file, and paste it into a text file. Save the file as signature.verify.dsa.xml.
- Create a Standard EXE project in Visual Basic. Save the empty project as verify.vbp to the same directory where you saved signature.verify.dsa.xml. Name the form file verify.frm.
- Create a reference to MSXML 5.0. To do this, select References... from the Project menu, then check the box for Microsoft XML, v5.0.
- Copy the Visual Basic code listing above, and paste it into the code editor to replace whatever is already there.
- Place a TextBox control onto the form. It should be named as Text1 (the default name). Click it to select it in the Properties window, and then modify the following properties for Text1: set the ScrollBars property to "2 – Vertical" and the MultiLine Property to True.
- Execute the code by selecting Start from the Run menu.
- Verify that the output is the same as that listed in the Output topic.