BlockChat

BlockChat is a decentralized messaging and transaction platform built using blockchain technology. It was created as part of the Distributed Systems course of the School of Electrical and Computer Engineering of the National Technical University of Athens during the academic year 2023-2024.

Contributors

gkapetanakis - George Kapetanakis (me)

Grade

The project was graded with a 10 out of 10.

Jump to a Section

• Repository Contents
• What is BlockChat and how does it work?
• Additional Info
• Setup Guide
• Usage Guide
• Testing Guide

Repository Contents

• handouts: The project description in both English and Greek.
• src: The project's source code, written in Rust.
• test_inputs: Files provided along with the project description, used to test the application.
• compose.yaml: This, along with the files in dockerfiles, are necessary for running the application locally using Docker.

What is BlockChat and how does it work?

BlockChat is a decentralized messaging and transaction platform built on blockchain technology. It enables users to exchange messages and conduct transactions without the need for a central authority. BlockChat utilizes a simple blockchain to record transactions and messages exchanged among participants. It employs a Proof-of-Stake algorithm for consensus. The currency used in the transactions is called BlockChat Coin (BCC). Users can send text messages for a fee, send BCC for a fee, or stake BCC in order to be able to validate transactions and earn validation rewards.

The system is relatively simple and works as follows:

• Firstly, the number of users (which will be called nodes for the rest of this section) participating in the system is known beforehand.
• Secondly, every node of the system knows the socket address of the first node of the network. This node is called the bootstrap node, as its responsibility is to bootstrap the network and initialize the blockchain.
• The bootstrapping process is as follows:
  • The bootstrap node starts listening on a socket address for join requests.
  • Each node of the system sends a join request containing their socket address and their wallet address (which is an RSA public key).
  • Once all the expected nodes have joined, the bootstrap node initializes the blockchain, giving every node a set amount of BCC (e.g. 1000 BCC). The blockchain, along with every node's socket/wallet address pair is then broadcast to everyone else.
• After the bootstrapping is complete, users are free to exchange text messages and send or stake coins.

What exactly is a node and how does a user interact with the system?

• A node is an executable intended to be run as a background service (daemon) on the user's machine. The user can then interact with this service using a CLI provided as a different executable.

If you want a more detailed explanation I suggest reading the source code. Check out bin/daemon.rs, protocol.rs and bootstrap.rs first. I've included detailed comments on every part of the code I deemed confusing or not having a clear rationale.

Additional Info

• The project was originally set up and tested on the IaaS ~okeanos-knossos platform, access to which was provided by my university.
• The application is in no way meant to be used for actual messaging, as it does not persist any data to disk and is not secure, among other reasons.

Setup Guide

• Make sure you have Rust installed, or install it from here. The most recent version I've tested this project with is 1.78.0. Newer versions of the language will probably work as well.
• Download or clone this repository in a local folder. I will refer to this folder as ./.
• Run ./cargo build if to compile the source code. Three different binaries can be built, daemon, client and helper, which can be specified as follows if needed: ./cargo build --bin <binary_name>. If you want to run any of the binaries you can use ./cargo run --bin <binary_name>. There is not much point in building or running the application like this, as it requires multiple instances of itself, able to communicate with each other, to work.
• [Recommended] To run the application locally without manually setting up multiple instances, you can use Docker. Just run ./docker compose up and wait.

Usage Guide

Will be updated soon.

Testing Guide

Will be updated soon.