(VB.NET) Verify XML Digital Signature

Verifies XML signatures in an XML file.

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

Dim sbXml As New Chilkat.StringBuilder
Dim success As Boolean = sbXml.LoadFile("qa_data/xml_dsig_verify/csioz_sample.xml","utf-8")
If (success <> True) Then
    Debug.WriteLine("Failed to load XML file.")
    Exit Sub
End If


Dim dsig As New Chilkat.XmlDSig

' First load the XML containing the signatures to be verified.
success = dsig.LoadSignatureSb(sbXml)
If (success <> True) Then
    Debug.WriteLine(dsig.LastErrorText)
    Exit Sub
End If


' It's possible that an XML document can contain multiple signatures.
' Each can be verified as follows:
Dim i As Integer = 0
While i < dsig.NumSignatures
    ' Select the Nth signature by setting the Selector property.
    dsig.Selector = i

    ' The bVerifyReferenceDigests argument determines if we want
    ' to also verify each reference digest.  If set to False,
    ' then only the SignedInfo part of the Signature is verified.
    Dim bVerifyReferenceDigests As Boolean = True
    Dim bVerified As Boolean = dsig.VerifySignature(bVerifyReferenceDigests)
    Debug.WriteLine("Signature " & (i + 1) & " verified = " & bVerified)

    i = i + 1
End While