Visual FoxPro

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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LOCAL lnSuccess
LOCAL loFtp

lnSuccess = 0

loFtp = CreateObject('Chilkat.Ftp2')

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

loFtp.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.
loFtp.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.
loFtp.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.
loFtp.TlsPinSet = "sha256//YLh1dUR9y6Kja30RrAn7JKnbQG/uEtLMkBgFF2Fuihg="

lnSuccess = loFtp.Connect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

*  SslServerCertVerified reports whether the certificate chain was successfully verified.
IF (loFtp.SslServerCertVerified) THEN
    ? "The server certificate was verified."
ENDIF

lnSuccess = loFtp.Disconnect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

RELEASE loFtp