UseKeychain
             On macOS, specifies whether the system should search for passphrases in the user's key-
             chain when attempting to use a particular key. When the passphrase is provided by the
             user, this option also specifies whether the passphrase should be stored into the key-
             chain once it has been verified to be correct.  The argument must be ``yes'' or ``no''.
             The default is ``no''.