Perl

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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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# 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.

my $mailman = Chilkat2::MailMan->new;

# 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.
my $cert = Chilkat2::Cert->new;
my $success = $cert->LoadPfxFile('qa_data/certs/client.pfx', 'pfx_password');
if (!$success) {
    print $cert->LastErrorText, "\n";
    exit;
}

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

$success = $mailman->VerifySmtpLogin();
if (!$success) {
    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.