(Mono C#) 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.

Chilkat.XmlDSig dsig = new Chilkat.XmlDSig();
Chilkat.StringBuilder sbXml = new Chilkat.StringBuilder();

bool success = sbXml.LoadFile("c:/aaworkarea/elias/3/face_f09006808443a699d1b.xml","utf-8");
if (success != true) {
    Debug.WriteLine("Failed to load XML file.");
    return;
}

success = dsig.LoadSignatureSb(sbXml);
if (success != true) {
    Debug.WriteLine(dsig.LastErrorText);
    return;
}

// Get the KeyInfo XML.
Chilkat.Xml xmlKeyInfo = dsig.GetKeyInfo();
if (dsig.LastMethodSuccess != true) {
    Debug.WriteLine(dsig.LastErrorText);
    return;
}

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>
string certBase64 = xmlKeyInfo.GetChildContent("*:X509Data|*:X509Certificate");
if (xmlKeyInfo.LastMethodSuccess != true) {
    Debug.WriteLine("No X509Certificate found in the KeyInfo.");
    return;
}

// Load a certificate object w/ the base64.
Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadFromBase64(certBase64);
if (success != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Examine the cert..
Debug.WriteLine("SubjectDN: " + cert.SubjectDN);
Debug.WriteLine("IssuerDN: " + cert.IssuerDN);
Debug.WriteLine("SerialNumber as Decimal: " + cert.SerialDecimal);