Perl

Verify and Pin the FTPS Server Certificate

Demonstrates the certificate-verification properties RequireSslCertVerify, TlsPinSet, and the read-only SslServerCertVerified.

Background: By default a TLS connection is not rejected merely because certificate-chain verification fails, so RequireSslCertVerify = true is the important hardening step — it makes an expired, unsigned, or untrusted certificate abort the connection. TlsPinSet adds public-key pinning on top: the handshake fails unless the server's SPKI fingerprint matches one you configured, defending against a mis-issued certificate that would otherwise validate. Pinning supplements verification rather than replacing it. SslServerCertVerified reports the outcome.

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use strict;
use warnings;
use Chilkat2;

my $ftp = Chilkat2::Ftp2->new;

$ftp->Hostname('ftp.example.com');
$ftp->Username('myFtpLogin');

$ftp->AuthTls(1);

# Normally you would not hard-code the password in source.  You should instead obtain it
# from an interactive prompt, environment variable, or a secrets vault.
$ftp->Password('myPassword');

# Reject the connection if the server certificate cannot be verified (expired, bad signature,
# untrusted chain, etc.).  The default is 0, which does not reject on verification
# failure -- set 1 for security.
$ftp->RequireSslCertVerify(1);

# Optionally pin the server's public key.  If none of the configured SPKI fingerprints matches,
# the TLS handshake fails.  Pinning supplements normal verification; it does not replace it.
$ftp->TlsPinSet('sha256//YLh1dUR9y6Kja30RrAn7JKnbQG/uEtLMkBgFF2Fuihg=');

my $success = $ftp->Connect();
if (!$success) {
    print $ftp->LastErrorText, "\n";
    exit;
}

# SslServerCertVerified reports whether the certificate chain was successfully verified.
if ($ftp->SslServerCertVerified) {
    print "The server certificate was verified.\n";
}

$success = $ftp->Disconnect();
if (!$success) {
    print $ftp->LastErrorText, "\n";
    exit;
}