(Delphi ActiveX) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

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_v9_5_0_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
sbCertBase64: TChilkatStringBuilder;
success: Integer;
cert: TChilkatCert;
pubKey: IPublicKey;
numBits: Integer;
xml: TChilkatXml;
binDat: TChilkatBinData;

begin
//  For this example, I have a certificate in raw base64 format (not PEM),
//  that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
sbCertBase64 := TChilkatStringBuilder.Create(Self);
success := sbCertBase64.LoadFile('qa_data/certs/base64Cert.txt','utf-8');

cert := TChilkatCert.Create(Self);
success := cert.LoadFromBase64(sbCertBase64.GetAsString());
if (success <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Get the public key.
pubKey := cert.ExportPublicKey();
if (cert.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  In Chilkat version v9.5.0.67, the KeySize property was added.
numBits := pubKey.KeySize;
Memo1.Lines.Add('Number of bits = ' + IntToStr(numBits));

//  If using an older version of Chilkat, the key size can be obtained like this:
xml := TChilkatXml.Create(Self);
xml.LoadXml(pubKey.GetXml());

binDat := TChilkatBinData.Create(Self);
binDat.AppendEncoded(xml.GetChildContent('Modulus'),'base64');

numBits := 8 * binDat.NumBytes;
Memo1.Lines.Add('Number of bits = ' + IntToStr(numBits));
end;