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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
cert: HCkCert;
success: Boolean;
extensionXmlStr: PWideChar;
xml: HCkXml;
sbDistPoint: HCkStringBuilder;

begin
cert := CkCert_Create();

success := CkCert_LoadFromFile(cert,'qa_data/certs/test_haswdt.cer');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

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

xml := CkXml_Create();
CkXml_LoadXml(xml,extensionXmlStr);

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

//  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 := CkStringBuilder_Create();
success := CkXml_GetChildContentSb(xml,'sequence|contextSpecific|contextSpecific|contextSpecific',sbDistPoint);
if (success = True) then
  begin
    CkStringBuilder_Decode(sbDistPoint,'base64','utf-8');
    Memo1.Lines.Add('CRL Distribution Point:  ' + CkStringBuilder__getAsString(sbDistPoint));
  end;

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

CkCert_Dispose(cert);
CkXml_Dispose(xml);
CkStringBuilder_Dispose(sbDistPoint);

end;