(.NET Core C#) Get Certificate Authority Information Access

Demonstrates how to get a certificate's Authority Information Access extension data (if it exists).

Note: This example requires Chilkat v9.5.0.76 or greater.

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

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

//  Get the Authority Information Access extension, which is at OID 1.3.6.1.5.5.7.1.1
string extensionXmlStr = cert.GetExtensionAsXml("1.3.6.1.5.5.7.1.1");
if (cert.LastMethodSuccess == false) {
    Debug.WriteLine("Certificate does not have the AuthInfoAccess extension.");
    return;
}

Chilkat.Xml xml = new Chilkat.Xml();
xml.LoadXml(extensionXmlStr);

//  See what we have..
Debug.WriteLine(xml.GetXml());

//  We should get XML like this:

//  <?xml version="1.0" encoding="utf-8" ?>
//  <sequence>
//      <sequence>
//          <oid>1.3.6.1.5.5.7.48.2</oid>
//          <contextSpecific tag="6" constructed="0">aHR0cDovL2NydC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1
//  cmVFbWFpbENBLmNydA==</contextSpecific>
//      </sequence>
//      <sequence>
//          <oid>1.3.6.1.5.5.7.48.1</oid>
//          <contextSpecific tag="6" constructed="0">aHR0cDovL29jc3AuY29tb2RvY2EuY29t</contextSpecific>
//      </sequence>
//  </sequence>

//  Typically, a certificate AIA(Authority Information access) contains 2 parts:
// 
//      On-line Certificate Status Protocol (1.3.6.1.5.5.7.48.1)
//      Certification Authority Issuer (1.3.6.1.5.5.7.48.2)
// 
//  The base64 content for each OID (in this case) is just a string.
//  The data can be accessed and decoded like this:

Chilkat.StringBuilder sbOcsp = new Chilkat.StringBuilder();
success = xml.GetChildContentSb("/C/oid,1.3.6.1.5.5.7.48.1|++",sbOcsp);
if (success == true) {
    sbOcsp.Decode("base64","utf-8");
    Debug.WriteLine("1.3.6.1.5.5.7.48.1:  " + sbOcsp.GetAsString());
}

Chilkat.StringBuilder sbIssuer = new Chilkat.StringBuilder();
success = xml.GetChildContentSb("/C/oid,1.3.6.1.5.5.7.48.2|++",sbIssuer);
if (success == true) {
    sbIssuer.Decode("base64","utf-8");
    Debug.WriteLine("1.3.6.1.5.5.7.48.2:  " + sbIssuer.GetAsString());
}

//  The output looks like this:

//  1.3.6.1.5.5.7.48.1:  http://ocsp.comodoca.com
//  1.3.6.1.5.5.7.48.2:  http://crt.comodoca.com/COMODORSAClientAuthenticationandSecureEmailCA.crt

//  -------------------------------------------------------------------------------
//  Note: The Chilkat path passed to GetChildContentSb is composed of two commands:
//  The first command is "/C/oid,1.3.6.1.5.5.7.48.1".   It says "traverse the XML tree from the caller
// node and stop at the 1st node having tag = "oid" and content = "1.3.6.1.5.5.7.48.1".
//  The "|" char separates the 1st command from the 2nd.
//  The 2nd command is "++" and says "move to the next sibling".