FMS is an open-source secure-chat server/webclient, written in C++, working with Freenet network.
It implements an totally censorship resistant chat system.
On Debian Wheezy it requires fixed libpoco to work properly described there. see Mempo/mempo-deb for instructions (as user get the code, run build in libpoco subdirectory, install created .deb files as root).
Apart from that, the user should run Freenet node (local server), and then on it's main page there is link to the Freenet Messaging System containing the C++ source code.
Compiling it on Debian is trivial (after installing dependencies).
The FMS application should be left running in background (nohup ./fms &) and then user can access web interface http://127.0.0.1:8080/ (configurable port) to use it via web-interface or configure NTTP access and later use program like eg Icedove as (GUI) client.