Keep in Touch aims to be a secure IM system for multiple platforms. It supports its own XML-based protocol as well as ICQ and AIM (toc). It provides encrypted connections between the server and client aswell as encrypted chat on all supported networks. The client can store contacts on the server allowing users to keep their contact lists between different locations.
KDX is a powerful cross-platform BBS-style encrypted Internet communications system that provides messaging, news, file and folder transfer, voice chat (Internet Telephone), text chat, remote access, trackers, and more. It uses strong encryption to protect communications for security and privacy. It is useful for groups that need to collaborate on a project via the Internet. It is also very useful for remote administration of a computer. It uses a client/server architecture.
WASTE is a mesh-based workgroup tool that allows for encrypted, private communication between distant parties on the Internet, independent of local network organization. It is RSA secured, and has been heralded as the most secure P2P connection protocol currently in development. WASTE functions as a both a server and a client under *nix, Mac OS X, and Windows, as well as a server only mode under *nix and Windows.
The Off-the-Record (OTR) Messaging proxy is a multi- platform proxy that allows you to have private conversations using the AIM client of your choice. It provides encryption, which prevents someone who intercepts your instant messages from reading them, authentication, which ensures that the correspondent is who you think it is, and perfect forward secrecy, which ensures that no previous conversation is compromised if you lose control of your private keys.