(Delphi DLL) How to Parse a X.509 Certificate and Extract its Public Key

Demonstrates how to load an X.509 certificate and extract the public key. Chilkat supports many certificate encodings:

• DER (binary) encoded certificates (.crt/.cer)
• PEM (BASE64) encoded certificates (.pem)
• Load Certificates Directly from Windows Certificate Stores
• PFX/PKCS12 (.pfx/.p12)
• Java KeyStore (.jks)
• Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)

Note: This example requires Chilkat v11.0.0 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, Cert, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
cert: HCkCert;
pubKey: HCkPublicKey;

begin
success := False;

cert := CkCert_Create();

// Load a DER (binary) encoded certificate.
// To load from a .pem or .p7b, or any other file format that contains
// just one certificate, call LoadFromFile in exactly the same way.
// The LoadFromFile method automatically detects the format and loads the certificate.
success := CkCert_LoadFromFile(cert,'qa_data/certs/testCert.cer');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

// Get the public key:
pubKey := CkPublicKey_Create();
CkCert_GetPublicKey(cert,pubKey);

// Examine the key type.
// A PublicKey object can contain an RSA, ECC, or DSA public key.
// The KeyType property will contain "rsa", "ecc", or "dsa".
Memo1.Lines.Add('key type = ' + CkPublicKey__keyType(pubKey));

CkCert_Dispose(cert);
CkPublicKey_Dispose(pubKey);

end;