To ensure the security of FTP transfers, it is also possible to encrypt the transport connection using Transport Layer Security (TLS). This protocol is described in RFC4217 (Securing FTP with TLS) and is usually referred to as FTPS. The names FTP Secure, FTP over TLS or FTP over SSL (name of the predecessor protocol) are also commonly used.
A FTPS server makes its key and the certificate available to the openFT for encryption purposes. No mutual authentication is carried out.
An openFT client is able to exchange encrypted outbound user data with a FTPS server if openFT-CR is installed on the openFT side and the FTP server supports the TLS protocol. AES is used as the encryption method. If the openFT client requires encryption of the user data in the request, but the FTP server does not support the TLS protocol, the request is rejected.
If the openFT client does not require encryption of the user data, the request description data is encrypted if the FTP server accepts the TLS protocol, otherwise the request description data is transferred in unencrypted form.