Chat CLI

A terminal chat application built with ratatui using the logos-chat library.

Features

💬 End-to-end encrypted messaging using the Double Ratchet algorithm
📁 File-based transport for local simulation (no network required)
💾 Persistent storage (SQLite)
🖥️ Beautiful terminal UI with ratatui

Usage

Run two instances with different usernames in separate terminals:

Terminal 1 (Alice)

cargo run -p chat-cli -- alice

Terminal 2 (Bob)

cargo run -p chat-cli -- bob

Establishing a Connection

In Alice's terminal, type /intro to generate an introduction bundle
Copy the bundle string (starts with Bundle:)
In Bob's terminal, type /connect alice <bundle> (paste Alice's bundle)
Bob can now send messages to Alice
Alice will see Bob's initial "Hello!" message and can reply

Commands

Command	Description
`/help`	Show available commands
`/intro`	Generate and display your introduction bundle
`/connect <user> <bundle>`	Connect to a user using their introduction bundle
`/peers`	List available peers
`/status`	Show connection status and your address
`/clear`	Clear message history
`/quit` or `Esc` or `Ctrl+C`	Exit the application

Sending Messages

Simply type your message and press Enter. Messages are automatically encrypted and delivered via file-based transport.

How It Works

File-Based Transport

Messages are passed between users via files in a shared directory:

Each user has an "inbox" directory at chat-cli-data/transport/<username>/
When Alice sends a message to Bob, it's written as a JSON file in Bob's inbox
Bob's client watches for new files and processes incoming messages
Files are deleted after processing

Storage

User data (identity keys, chat state) is stored in SQLite databases at:

chat-cli-data/<username>.db

Encryption

All messages are encrypted using:

X3DH key agreement for initial key exchange
Double Ratchet algorithm for ongoing message encryption
ChaCha20-Poly1305 for authenticated encryption

Example Session

# Terminal 1 (Alice)
$ cargo run -p chat-cli -- alice

/intro
# Output: Bundle:abc123...def456

# Terminal 2 (Bob)  
$ cargo run -p chat-cli -- bob

/connect alice Bundle:abc123...def456
# Connected! Bob sends "Hello!" automatically

# Now type messages in either terminal to chat!

Architecture

chat-cli/
├── src/
│   ├── main.rs       # Entry point
│   ├── app.rs        # Application state and logic
│   ├── transport.rs  # File-based message transport
│   └── ui.rs         # Ratatui terminal UI

The CLI uses logos-chat as a library without modifying it:

ChatManager handles all encryption/decryption
Introduction bundles enable key exchange
AddressedEnvelope carries encrypted messages

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