(Delphi ActiveX) Accept TLS Connection with Client Authentication

Demonstrates how to accept a TLS connection requiring client authentication. This is the case where the TLS client sends a certificate. It is also known as "Two-Way SSL".

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;
clientSock: IChilkatSocket;
maxWaitMillisec: Integer;
receivedMsg: WideString;

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.
// Note: This is the server's certificate.

cert := TChilkatCert.Create(Self);
// The 1st argument is the file path, the 2nd arg is the 
// PFX file's password:
success := cert.LoadPfxFile('chilkat.pfx','test');
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');

// Use the 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;

// If accepting an SSL/TLS connection, the SSL handshake is part of the connection
// establishment process. This involves a few back-and-forth messages between the 
// client and server to establish algorithms and a shared key to create the secure 
// channel. The sending and receiving of these messages are governed by the 
// MaxReadIdleMs and MaxSendIdleMs properties. If these properties are set to 0 
// (and this is the default unless changed by your application), then the 
// AcceptNextConnection can hang indefinitely during the SSL handshake process. 
// Make sure these properties are set to appropriate values before calling AcceptNextConnection.

// Set a 10 second max for waiting to read/write.  This is for the SSL/TLS handshake establishment.
listenSslSocket.MaxReadIdleMs := 10000;
listenSslSocket.MaxSendIdleMs := 10000;

// Accept a single client connection and establish the secure SSL/TLS channel:

maxWaitMillisec := 20000;
clientSock := listenSslSocket.AcceptNextConnection(maxWaitMillisec);
if (listenSslSocket.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(listenSslSocket.LastErrorText);
    Exit;
  end;

// The client (in this example) is going to send a "Hello Server! -EOM-" 
// message.  Read it:
receivedMsg := clientSock.ReceiveUntilMatch('-EOM-');
if (clientSock.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(clientSock.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add(receivedMsg);

// Send a "Hello Client! -EOM-" message:
success := clientSock.SendString('Hello Client! -EOM-');
if (success <> 1) then
  begin
    Memo1.Lines.Add(clientSock.LastErrorText);
    Exit;
  end;

// Close the connection with the client
// Wait a max of 20 seconds (20000 millsec)
success := clientSock.Close(20000);
end;