(Delphi ActiveX) Examine Client Certificates for an Accepted TLS Connection

Demonstrates how to access the client certificates for a TLS connection accepted by your application acting as the server.

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
listenSslSocket: TChilkatSocket;
cert: TChilkatCert;
success: Integer;
myPort: Integer;
backLog: Integer;
maxWaitMillisec: Integer;
clientSock: IChilkatSocket;
numClientCerts: Integer;
i: Integer;
clientCert: IChilkatCert;

begin
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

listenSslSocket := TChilkatSocket.Create(Self);

// An SSL/TLS server needs a digital certificate.  This example loads it from a PFX file.
// This is the server's certificate.

cert := TChilkatCert.Create(Self);
success := cert.LoadPfxFile('qa_data/serverCert/myServerCert.pfx','pfx_password');
if (success <> 1) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

// To accept client client certificates in the TLS handshake,
// we must indicate a list of acceptable client certificate root CA DN's
// that are allowed.  (DN is an acronym for Distinguished Name.)
// Call AddSslAcceptableClientCaDn once for each acceptable CA DN.
// Here are a few examples so you can see the general format of a DN.
listenSslSocket.AddSslAcceptableClientCaDn('C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root');
listenSslSocket.AddSslAcceptableClientCaDn('O=Digital Signature Trust Co., CN=DST Root CA X3');

// Initialize with our server's TLS certificate.
success := listenSslSocket.InitSslServer(cert.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(listenSslSocket.LastErrorText);
    Exit;
  end;

// Bind and listen on a port:
myPort := 8123;
// Allow for a max of 5 queued connect requests.
backLog := 5;
success := listenSslSocket.BindAndListen(myPort,backLog);
if (success <> 1) then
  begin
    Memo1.Lines.Add(listenSslSocket.LastErrorText);
    Exit;
  end;

// Accept the next incoming connection.
maxWaitMillisec := 20000;
clientSock := listenSslSocket.AcceptNextConnection(maxWaitMillisec);
if (listenSslSocket.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(listenSslSocket.LastErrorText);
    Exit;
  end;

// Examine the client certs chain.  The 1st cert will be the client certificate, and
// the subsequent certs will be the certs in the chain of authentication.
numClientCerts := clientSock.NumReceivedClientCerts;
Memo1.Lines.Add('numClientCerts = ' + IntToStr(numClientCerts));

i := 0;
while i < numClientCerts do
  begin
    clientCert := clientSock.GetReceivedClientCert(i);
    Memo1.Lines.Add(clientCert.SubjectDN);

    i := i + 1;
  end;

// Close the connection with the client
success := clientSock.Close(1000);
end;