PubliChat

PubliChat is a semi-private chatting application. Chats are encrypted with their title as a key. Every chat is accessible to anyone, provided they know the chat's title. The title is never sent to the server, so the server can't decrypt the chat contents. This way, the server does not need to be trusted.

Server written in Rust. FLOSS!

Example uses

• Chat securely and privately by picking a secure title (like a strong password)
• Make a private note for yourself by picking a secure title and not sharing it
• Discuss topics in 'public' chats with insecure titles (eg. Baking, Fishing or Chess)
• Discuss webpages with no comments section (set the title to page's url)

How to use

Web version

• Go to publi.chat
• Enter a chat title on the top to fetch messages start reading
• Enter a username and message on the bottom to send something

Server

• Clone the repository with git clone [email protected]:GrishaVar/publichat.git
• Open directory with cd publichat
• Launch server with cargo r --release --bin server [socket_addr] data_directory/
  • socket_addr should be an (ip or domain) with a port
  • data_directory/ is where all chat data will be stored

TUI

• Clone the repository with git clone [email protected]:GrishaVar/publichat.git
• Open directory with cd publichat
• Launch client with cargo r --release socket_addr chat_title username
  • socket_addr should be an (ip or domain) with a port

Visual explainer

Titles

A chat title is used to encrypt the chat's contents. Do not share a chat's title with someone unless you want them to read the chat! The title's hash is the chat id. Only the chat id is sent to the server. Therefore, the server doesn't know the title and thus cannot decrypt and read the chat.

Usernames

To verify the authorship of each message, users must choose a username. This username is not public and should be chosen as a strong password would be. Do not share your secret username with anyone!

Usernames are used to generate a public-key system. Each message is signed, clients automatically verify the signatures of each incoming message. Public keys are used to identify message authors to other users. A malicious user can display the same ID publicly, but they can not sign their messages with it!

Tech

• Signatures are done with Ed19255
• Chats are encrypted with AES
• Title and Username hashing is done with Argon2
• Other hashing is done with SHA-3