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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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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

$ftp = New-Object Chilkat.Ftp2

$ftp.Hostname = "ftp.example.com"
$ftp.Username = "myFtpLogin"

$ftp.AuthTls = $true

#  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 $false, which does not reject on verification
#  failure -- set $true for security.
$ftp.RequireSslCertVerify = $true

#  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="

$success = $ftp.Connect()
if ($success -eq $false) {
    $($ftp.LastErrorText)
    exit
}

#  SslServerCertVerified reports whether the certificate chain was successfully verified.
if ($ftp.SslServerCertVerified) {
    $("The server certificate was verified.")
}

$success = $ftp.Disconnect()
if ($success -eq $false) {
    $($ftp.LastErrorText)
    exit
}