(VB.NET) Get Certificates within XML Signature

Demonstrates how to get the certificates contained within an XML signature.

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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

' Load XML containing one or more signatures.
Dim success As Boolean = sbXml.LoadFile("qa_data/xml_dsig_valid_samples/multipleSigners/sp.pdf.XAdES.xml","utf-8")
If (success = False) Then
    Debug.WriteLine("Failed to load the XML file..")
    Exit Sub
End If


Dim dsig As New Chilkat.XmlDSig

' First load the XML containing the signatures to be verified.
' Note that this particular Signature already contains the RSA public key that will be used
' for verification.
success = dsig.LoadSignatureSb(sbXml)
If (success <> True) Then
    Debug.WriteLine(dsig.LastErrorText)
    Exit Sub
End If


' For each signature, verify and also get the certificate(s) contained within each Signature.
Dim i As Integer = 0
Dim saCerts As New Chilkat.StringArray
Dim cert As New Chilkat.Cert

Debug.WriteLine("numSignatures = " & dsig.NumSignatures)

While i < dsig.NumSignatures
    ' Select the Nth signature by setting the Selector property.
    dsig.Selector = i

    Dim bVerifyReferenceDigests As Boolean = True
    Dim bVerified As Boolean = dsig.VerifySignature(bVerifyReferenceDigests)
    Debug.WriteLine("Signature " & (i + 1) & " verified = " & bVerified)

    ' Get the certificates embedded in this signature.
    saCerts.Clear()
    success = dsig.GetCerts(saCerts)
    If (success = True) Then
        Dim j As Integer = 0
        While j < saCerts.Count
            success = cert.LoadFromBase64(saCerts.GetString(j))
            If (success = True) Then
                Debug.WriteLine("    " & cert.SubjectDN)
            End If

            j = j + 1
        End While
    End If


    i = i + 1
End While