Delphi ActiveX

Use a TLS Client Certificate

Demonstrates the Chilkat MailMan.SetSslClientCert method, which sets the client-side certificate to use for SSL/TLS connections. This is typically not required — most SSL/TLS connections authenticate the server only. This example loads a client certificate from a PFX and uses it when connecting.

Background: In an ordinary TLS handshake only the server presents a certificate, and the client proves who it is later with a password. Mutual TLS adds a second leg: the client also presents a certificate, so it is authenticated cryptographically at the transport layer. Some corporate or high-security mail servers require this. Because the client must prove possession of the key, the certificate needs its private key — hence loading from a PFX.

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var
success: Integer;
mailman: TChilkatMailMan;
cert: TChilkatCert;

begin
success := 0;

//  Demonstrates the MailMan.SetSslClientCert method, which sets the client-side certificate
//  to use for SSL/TLS connections.  This is typically not required -- most SSL/TLS
//  connections authenticate the server only.

mailman := TChilkatMailMan.Create(Self);

//  Configure the SMTP server connection.
mailman.SmtpHost := 'smtp.example.com';
mailman.SmtpPort := 465;
mailman.SmtpSsl := 1;
mailman.SmtpUsername := 'user@example.com';
mailman.SmtpPassword := 'myPassword';

//  Load the client certificate (with its private key) from a PFX file.
cert := TChilkatCert.Create(Self);
success := cert.LoadPfxFile('qa_data/certs/client.pfx','pfx_password');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Use this certificate to identify the client during the TLS handshake.
success := mailman.SetSslClientCert(cert.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(mailman.LastErrorText);
    Exit;
  end;

success := mailman.VerifySmtpLogin();
if (success = 0) then
  begin
    Memo1.Lines.Add(mailman.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Connected using a TLS client certificate.');

//  Note: The path "qa_data/certs/client.pfx" is a relative local filesystem path,
//  relative to the current working directory of the running application.