(.NET Core C#) Get Certificate User Principal Name (UPN)

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Demonstrates how to get a certificate's UPN from the SAN (Subject Alternative Name). Most certificates do not have a UPN. This example only applies to those certificates that have a User Principal Name.

Note: This example requires Chilkat v9.5.0.90 or greater due to fixes made in getting the UPN from the SAN.

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Chilkat.Cert cert = new Chilkat.Cert();

bool success = cert.LoadFromFile("qa_data/certs/sample.cer");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

Chilkat.Xml xml = new Chilkat.Xml();
xml.LoadXml(cert.SubjectAlternativeName);
Debug.WriteLine(xml.GetXml());

// A certificate with a User Principal Name in the SAN might have this:

// <SubjectAltName>
//     <rfc822Name>joe@example.com</rfc822Name>
//     <name type="oid" oid="1.3.6.1.4.1.311.20.2.3">joe@example.com</name>
// </SubjectAltName>

// The OID 1.3.6.1.4.1.311.20.2.3 is for the User Principal Name.
string upn = xml.ChilkatPath("/A/name,oid,1.3.6.1.4.1.311.20.2.3|*");
if (xml.LastMethodSuccess == false) {
    Debug.WriteLine("No user principle name.");
}
else {
    Debug.WriteLine("User Principle Name = " + upn);
}