(Lianja) 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.

loDsig = createobject("CkXmlDSig")
loSbXml = createobject("CkStringBuilder")

llSuccess = loSbXml.LoadFile("c:/aaworkarea/elias/3/face_f09006808443a699d1b.xml","utf-8")
if (llSuccess <> .T.) then
    ? "Failed to load XML file."
    release loDsig
    release loSbXml
    return
endif

llSuccess = loDsig.LoadSignatureSb(loSbXml)
if (llSuccess <> .T.) then
    ? loDsig.LastErrorText
    release loDsig
    release loSbXml
    return
endif

// Get the KeyInfo XML.
loXmlKeyInfo = loDsig.GetKeyInfo()
if (loDsig.LastMethodSuccess <> .T.) then
    ? loDsig.LastErrorText
    release loDsig
    release loSbXml
    return
endif

? loXmlKeyInfo.GetXml()
? "----"

// 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>
lcCertBase64 = loXmlKeyInfo.GetChildContent("*:X509Data|*:X509Certificate")
if (loXmlKeyInfo.LastMethodSuccess <> .T.) then
    ? "No X509Certificate found in the KeyInfo."
    release loDsig
    release loSbXml
    return
endif

// Load a certificate object w/ the base64.
loCert = createobject("CkCert")
llSuccess = loCert.LoadFromBase64(lcCertBase64)
if (llSuccess <> .T.) then
    ? loCert.LastErrorText
    release loDsig
    release loSbXml
    release loCert
    return
endif

// Examine the cert..
? "SubjectDN: " + loCert.SubjectDN
? "IssuerDN: " + loCert.IssuerDN
? "SerialNumber as Decimal: " + loCert.SerialDecimal

release loXmlKeyInfo


release loDsig
release loSbXml
release loCert