(Delphi ActiveX) Get Certificate CRL Distribution Points

Demonstrates how to get a certificate's CRL Distribution Points extension data (assuming it exists). In the vast majority of cases, there will be one CRL Distribution Point.

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

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
cert: TChilkatCert;
success: Integer;
extensionXmlStr: WideString;
xml: TChilkatXml;
sbDistPoint: TChilkatStringBuilder;

begin
cert := TChilkatCert.Create(Self);

success := cert.LoadFromFile('qa_data/certs/test_haswdt.cer');
if (success <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

// Get the CRL Distribution Points extension, which is at OID 2.5.29.31
extensionXmlStr := cert.GetExtensionAsXml('2.5.29.31');
if (cert.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add('Certificate does not have the CDP extension.');
    Exit;
  end;

xml := TChilkatXml.Create(Self);
xml.LoadXml(extensionXmlStr);

// See what we have..
Memo1.Lines.Add(xml.GetXml());

// We should get XML like this:

// <?xml version="1.0" encoding="utf-8" ?>
// <sequence>
//     <sequence>
//         <contextSpecific tag="0" constructed="1">
//             <contextSpecific tag="0" constructed="1">
//                 <contextSpecific tag="6" constructed="0">aHR0cDovL2NybC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1
// cmVFbWFpbENBLmNybA==</contextSpecific>
//             </contextSpecific>
//         </contextSpecific>
//     </sequence>
// </sequence>
// 

// Assuming there is one CRL Distribution Point...
sbDistPoint := TChilkatStringBuilder.Create(Self);
success := xml.GetChildContentSb('sequence|contextSpecific|contextSpecific|contextSpecific',sbDistPoint.ControlInterface);
if (success = 1) then
  begin
    sbDistPoint.Decode('base64','utf-8');
    Memo1.Lines.Add('CRL Distribution Point:  ' + sbDistPoint.GetAsString());
  end;

// Sample output:
// CRL Distribution Point:  http://crl.comodoca.com/COMODORSAClientAuthenticationandSecureEmailCA.crl
end;