Hmm... I don't think this is actually a secure approach, as by default X is not secure. Any client with access can do things like sniff and inject keystrokes (even forwarded over SSH, depending on the value of ForwardX11Trusted in ssh_config):
I could be wrong. Apparently X11 has the SECURITY and XACE extensions which are theoretically capable of preventing this, but nobody uses them (except SSH, see above). It's possible that DragonFlyBSD has these integrated somehow and makes the directions secure, but I don't think so.
http://theinvisiblethings.blogspot.de/2011/04/linux-security...
I could be wrong. Apparently X11 has the SECURITY and XACE extensions which are theoretically capable of preventing this, but nobody uses them (except SSH, see above). It's possible that DragonFlyBSD has these integrated somehow and makes the directions secure, but I don't think so.