PHP Extension

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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PHP Extension

<?php

include("chilkat.php");

$success = false;

//  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 = new CkMailMan();

//  Configure the SMTP server connection.
$mailman->put_SmtpHost('smtp.example.com');
$mailman->put_SmtpPort(465);
$mailman->put_SmtpSsl(true);
$mailman->put_SmtpUsername('user@example.com');
$mailman->put_SmtpPassword('myPassword');

//  Load the client certificate (with its private key) from a PFX file.
$cert = new CkCert();
$success = $cert->LoadPfxFile('qa_data/certs/client.pfx','pfx_password');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

//  Use this certificate to identify the client during the TLS handshake.
$success = $mailman->SetSslClientCert($cert);
if ($success == false) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

$success = $mailman->VerifySmtpLogin();
if ($success == false) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

print 'Connected using a TLS client certificate.' . "\n";

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

?>