a lightweight encrypted chat server. clients connect over TCP, perform a Diffie-Hellman key exchange, and communicate through HMAC-authenticated encrypted frames. there are no accounts, no logs, and no persistent state beyond an optional ban list.

• E2E encryption via DH key exchange (RFC 3526 2048-bit group) + HMAC-SHA256
• multiple rooms, created on demand
• direct messages across rooms
• nicknames with server-side validation
• persistent ban list (by nickname or IP) (stored in a plain text file)
• interactive server console

./retchat [port] [bans_file]

defaults: port 6677, bans file bans.txt. the bans file is created automatically on first ban and loaded on startup if it exists.

the server accepts commands on stdin while running:

a native Android client is available at retchat-android. features a collapsible connect panel, side panel for room and DM navigation, per-conversation message history (non-persistent), and a persistent background connection via a foreground service.

a terminal client for Linux is available at retchat-linux, for those looking for a barebones client that just works (most of the time).

./retchat-client [-h host] [-p port] [-n nickname] [-r room]

default host: retucio.me, port 6677, room lobby.

client commands:

/nick <nick>          change your nickname
/join <room>          join a room (created if it doesn't exist)
/dm <nick> <message>  send a direct message
/quit                 disconnect and exit

full protocol spec here.

Plain text, one entry per line:

nick:johndoe
ip:1.2.3.4

the file is read on startup and written after every ban or unban. it can be edited manually while the server is stopped.

MIT, i guess