(Delphi DLL) 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 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, Socket;

...

procedure TForm1.Button1Click(Sender: TObject);
var
listenSslSocket: HCkSocket;
cert: HCkCert;
success: Boolean;
myPort: Integer;
backLog: Integer;
maxWaitMillisec: Integer;
clientSock: HCkSocket;
numClientCerts: Integer;
i: Integer;
clientCert: HCkCert;

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

listenSslSocket := CkSocket_Create();

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

cert := CkCert_Create();
success := CkCert_LoadPfxFile(cert,'qa_data/serverCert/myServerCert.pfx','pfx_password');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    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.
CkSocket_AddSslAcceptableClientCaDn(listenSslSocket,'C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root');
CkSocket_AddSslAcceptableClientCaDn(listenSslSocket,'O=Digital Signature Trust Co., CN=DST Root CA X3');

// Initialize with our server's TLS certificate.
success := CkSocket_InitSslServer(listenSslSocket,cert);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(listenSslSocket));
    Exit;
  end;

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

// Accept the next incoming connection.
maxWaitMillisec := 20000;
clientSock := CkSocket_AcceptNextConnection(listenSslSocket,maxWaitMillisec);
if (CkSocket_getLastMethodSuccess(listenSslSocket) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(listenSslSocket));
    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 := CkSocket_getNumReceivedClientCerts(clientSock);
Memo1.Lines.Add('numClientCerts = ' + IntToStr(numClientCerts));

i := 0;
while i < numClientCerts do
  begin
    clientCert := CkSocket_GetReceivedClientCert(clientSock,i);
    Memo1.Lines.Add(CkCert__subjectDN(clientCert));
    CkCert_Dispose(clientCert);
    i := i + 1;
  end;

// Close the connection with the client
success := CkSocket_Close(clientSock,1000);

CkSocket_Dispose(clientSock);

CkSocket_Dispose(listenSslSocket);
CkCert_Dispose(cert);

end;