Overkill Chat

An experimental peer to peer secure chat program written in rust. Uses tor hidden services and noise protocol. Repository includes both a simple cli interface to the encrypted client program and a gtk gui. Chat program is comparable to ricochet.

Design

• anonymous and metadata resistant communications (tor network)
• strong end to end message encryption+integrity with noise protocol
• fully p2p architecture, no servers
• simple open-source client code in a memory safe language (rust)

Building

make

Build with make, this will generate binaries for the gui and chat client. Chat client requires a rust compiler and gui requires gcc and gtk3 development libraries to build from source. To build either binary individually you can specify the name of the program as follows.

make overkill-chat
make overkill-gui

Setup

Overkill chat will only communicate over tor hidden services. To run the program you must have the tor service running and a hidden service configured to forward traffic. Default listening port is 7878. To connect to a peer you must exchange hidden service addresses over another channel.

Example torrc lines:

HiddenServiceDir /home/user/my_hidden_service
HiddenServicePort 7878 127.0.0.1:7878

GUI Setup

To run the gui and connect to a peer you must add their hidden service address to the overkill-start.sh script. Change the following line

hservice=peer-hidden-service-address

Installing

Running make install or the installation script will place the binaries and various configuration files in the appropriate directories for most linux distributions.

make install

or

./install.sh

Connect to Peer

Once you have exchanged hidden service names each peer should run the following command. Both programs must be active at the same time to establish a connection. The program will attempt to connect for n seconds before timing out.

overkill_chat --host peershiddenservicename.onion

For the GUI, simply find 'overkill' in your application menu and run it.

Pre-shared Secret

The security of the inital key exchange can be improved by using a preshared secret. When connecting you may optionally specify a password which will be run through pbkdf2 to create a 32 byte key. This key is only used to protect the initial handshake.

overkill_chat --host peershiddenservicename.onion --password secretsharedwithpeer