(Delphi DLL) 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 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;
clientSock: HCkSocket;
maxWaitMillisec: Integer;
receivedMsg: PWideChar;

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

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

// Use the 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;

// 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.
CkSocket_putMaxReadIdleMs(listenSslSocket,10000);
CkSocket_putMaxSendIdleMs(listenSslSocket,10000);

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

maxWaitMillisec := 20000;
clientSock := CkSocket_AcceptNextConnection(listenSslSocket,maxWaitMillisec);
if (CkSocket_getLastMethodSuccess(listenSslSocket) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(listenSslSocket));
    Exit;
  end;

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

Memo1.Lines.Add(receivedMsg);

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

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

CkSocket_Dispose(clientSock);

CkSocket_Dispose(listenSslSocket);
CkCert_Dispose(cert);

end;