(VB.NET) Examine KeyInfo Certificate in XML Signature

This example loads signed XML and gets the signing certificate, assuming the certificate is contained in X509Certificate within the KeyInfo.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim dsig As New Chilkat.XmlDSig
Dim sbXml As New Chilkat.StringBuilder

Dim success As Boolean = sbXml.LoadFile("c:/aaworkarea/elias/3/face_f09006808443a699d1b.xml","utf-8")
If (success <> True) Then
    Debug.WriteLine("Failed to load XML file.")
    Exit Sub
End If


success = dsig.LoadSignatureSb(sbXml)
If (success <> True) Then
    Debug.WriteLine(dsig.LastErrorText)
    Exit Sub
End If


' Get the KeyInfo XML.
Dim xmlKeyInfo As Chilkat.Xml = dsig.GetKeyInfo()
If (dsig.LastMethodSuccess <> True) Then
    Debug.WriteLine(dsig.LastErrorText)
    Exit Sub
End If


Debug.WriteLine(xmlKeyInfo.GetXml())
Debug.WriteLine("----")

' Assuming the X509Certificate is in the KeyInfo, it will look like this:

'   <ds:KeyInfo Id="...">
'     <ds:KeyValue>
'     ...  
'     <ds:X509Data>
'       <ds:X509Certificate>MIIHAz...</ds:X509Certificate>
'     </ds:X509Data>
'   </ds:KeyInfo>
Dim certBase64 As String = xmlKeyInfo.GetChildContent("*:X509Data|*:X509Certificate")
If (xmlKeyInfo.LastMethodSuccess <> True) Then
    Debug.WriteLine("No X509Certificate found in the KeyInfo.")
    Exit Sub
End If


' Load a certificate object w/ the base64.
Dim cert As New Chilkat.Cert
success = cert.LoadFromBase64(certBase64)
If (success <> True) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


' Examine the cert..
Debug.WriteLine("SubjectDN: " & cert.SubjectDN)
Debug.WriteLine("IssuerDN: " & cert.IssuerDN)
Debug.WriteLine("SerialNumber as Decimal: " & cert.SerialDecimal)