Mostro Chat

A a minimalist peer-to-peer chat application written in Rust, utilizing the Nostr protocol for decentralized and secure communication. It integrates the nostr-sdk for event handling and encryption, and features a terminal-based user interface (TUI) built with ratatui and crossterm.

Features

• Private Messaging: Utilizes Nostr protocol for decentralized communication.
• End-to-End Encryption: Employs NIP-44 for encrypting messages, ensuring privacy.
• Terminal Interface: User-friendly text-based interface powered by Ratatui.
• Participant Mode: Send and receive encrypted messages using your private key and the recipient's public key.
• Observer Mode: View encrypted messages using a shared secret key, without the ability to send messages.
• Real-time Updates: Displays messages in real-time as they are received from the Nostr relay.
• Message History: Shows recent messages within a configurable time window (default: 10 minutes).
• Shared Key Display: Option to display or hide the shared secret key in observer mode.

Prerequisites

• Rust and Cargo: Ensure you have Rust installed. If not, follow the instructions on the official Rust website.
• Nostr Relay: This application is configured to use wss://relay.mostro.network by default. You can modify this in the source code if needed.

Installation

Clone the repository:

    git clone https://github.com/MostroP2P/mostro-chat.git
    cd mostro-chat

Run the program:

    cargo run -- -s <sender_secret> -p <receiver_pubkey>

Usage

For chat participants the application requires two arguments:

    -s, --sender-secret <SENDER_SECRET>: Your private key (in hex or bech32 format, e.g., nsec1...).
    -p, --receiver-pubkey <RECEIVER_PUBKEY>: The recipient’s public key (in hex or bech32 format, e.g., npub1...).

Example:

cargo run -- -s yourprivatekeyhere -p whoyouwanttotalkpubkeyhere

For the observer the application requires only the shared key:

    -k, --shared-key <SHARED_KEY>: Shared secret key (hex).

Example:

cargo run -- -k sharedprivatekeyhere

Usage

Once the application is running:

• Type your message in the input area at the bottom of the terminal.
• Press Enter to send the message (Participant mode only).
• Press Esc to exit the application.
• Press Tab to toggle the visibility of the shared secret key in the "Shared Key" area.

Message Display

• Messages appear in the main area.
• Only messages from the last 10 minutes (600 seconds) are shown by default.
• Sent messages are prefixed with "You: ".
• Received messages are prefixed with "hex_pubkey: ".

Configuration

The following constants in the code can be modified:

• N_SECONDS: Time window for displaying messages (default: 600 seconds). Edit this in main.rs.
• POW_DIFFICULTY: Proof-of-work difficulty for outgoing messages (default: 2). Adjust in main.rs.
• RELAY_URL: Nostr relay URL (default: wss://relay.mostro.network). Change in main.rs.

How It Works

Shared Key Generation: Uses ECDH with the sender’s private key and receiver’s public key to create a shared key.

Message Encryption: Messages are wrapped in a simplified NIP-59 event, encrypted with the shared key, and signed with an ephemeral key.

Event Subscription: Subscribes to events targeting the shared key’s public key via the Nostr relay.

Real-Time Updates: Decrypts and displays incoming messages in the TUI if they fall within the time window.

Technical Details

NIP-59 Simplification: The app uses a custom, non-standard NIP-59 implementation for gift-wrapped events.

Asynchronous Handling: Employs tokio for managing Nostr client tasks and TUI updates concurrently.

You can find more information about here

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributing

Contributions are encouraged! Feel free to open issues or submit pull requests on GitHub.