(Delphi DLL) 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 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, Xml, StringBuilder, BinData, Cert, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
sbCertBase64: HCkStringBuilder;
success: Boolean;
cert: HCkCert;
pubKey: HCkPublicKey;
numBits: Integer;
xml: HCkXml;
binDat: HCkBinData;

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

cert := CkCert_Create();
success := CkCert_LoadFromBase64(cert,CkStringBuilder__getAsString(sbCertBase64));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

// Get the public key.
pubKey := CkCert_ExportPublicKey(cert);
if (CkCert_getLastMethodSuccess(cert) <> True) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

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

// If using an older version of Chilkat, the key size can be obtained like this:
xml := CkXml_Create();
CkXml_LoadXml(xml,CkPublicKey__getXml(pubKey));

binDat := CkBinData_Create();
CkBinData_AppendEncoded(binDat,CkXml__getChildContent(xml,'Modulus'),'base64');

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

CkPublicKey_Dispose(pubKey);

CkStringBuilder_Dispose(sbCertBase64);
CkCert_Dispose(cert);
CkXml_Dispose(xml);
CkBinData_Dispose(binDat);

end;