FiSH is an elegant encryption addon which works with the IRC clients irssi, xchat and mIRC.
 Why FiSH?
FiSH allows you to encrypt private messages as well as channels on IRC. This is generally a very good thing because all "private" /msg messages on IRC are transmitted in plain text - readable to the whole world (as in all the routers between you, the IRC server and the person you are communicating with).
It should be noted that I am not aware of any other solution for encrypting IRC messges and channels. A GnuPG plugin which would ideally be available for multiple IRC clients would obviously be amazing; but until or unless someone makes that.. there's FiSH.
Installation is very easy indeed, specially if you use the precompiled binaries included in the source tarball.
FiSH enables you to send private encrypted messages to other IRC users and also allows you to encrypt entire channels. Non-FiSH users (and FiSH users who are not given the channel key) see what is written in such channels as pure gibberish.
FiSH can and should be used on public IRC servers as well as private IRC servers on anonymity networks such as Tor.
- Homepage: http://fish.sekure.us/